Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR EXTENDING different from those needed to extend
shelf-life of fresh
SHELF-LIFE AND PREVENTION OF chilled meat for periods of up to
fifteen weeks. Deterioration
DISCOLORATION OF MEAT of chilled meats primarily takes place
at the cut or uncut
muscle surface. In long term storage at a centralized pack-
RELATED APPLICATION DATA aging and storage operation, primal
cuts are placed in an
atmosphere saturated with carbon dioxide (CO2) (100%)
[0001] This application is a continuation-in-part of U.S. which contains
very low residual oxygen (02), and these
application Ser. No. 10/192,916 and U.S. application Ser. primal cuts
stored at ¨1.5+/-0.5 C.
No. 10/434,010, which is also a continuation-in-part of Ser.
[0007] At the end of required storage, meat is removed and
No. 10/192,916, and claims the benefit of U.S. Provisional
fabricated into retail or food service cuts. New fresh surfaces
Application 60/303,985, U.S. Provisional Application
are created in the process, revitalizing the appearance of the
60/379,668, and U.S. Provisional Application 60/729,077.
meat cuts; and when the new surfaces of the meat cuts are
Applicant further incorporates these previous filings by
prepared for retail display the normal expectation is a further
reference.
four days of shelf-life. Depending on the variability of the
meat species, the shelf-life is usually limited by develop-
TECHNICAL FIELD OF THE INVENTION
ment of undesirable organoleptic changes, where defects in
[0002] The present invention relates to a packaging sys- color are usually
independent of the microbial presence. The
tern, method, and apparatus of increasing the shelf-life of latter has a
lactic acid bacterial population, which maximizes
retail-ready meat cuts and preventing discoloration of meat under storage
conditions at levels about 108 cfu/cm2 well
products. before the shelf-life expiration.
[0008] However, with centralized distribution of retail
BACKGROUND OF THE INVENTION ready fresh meat, circumstances and
storage requirements
are different. The wholesale storage period following initial
[0003] Meat production and packaging is well known in
packaging of the retail cuts is in the range of 20-30 days and
the industry. Traditionally, once a primal cut of meat has
- prepared products must withstand the rigor of retail display
been made, it is placed in a package containing ambient air
for up to two days thereafter without further manipulation of
and the lidding material is fed from a roll and over the tray
the contents of the package. Retail packages are simply
covering the meat cut. The tray edges are typically sealed to
moved from their storage container (usually a unit or over-
form the finished product. However, since the air allows the
meat to become discolored due to the onset of metmyoglo- wrap containing a
modified atmosphere) to retail display
where desirable meat color develops upon exposure to air.
bin, the meat normally undergoes vacuum skin packaging in
The present commercial centralized meat operations only
order to maintain freshness and reduce spoilage of the meat
provide one to two weeks of shelf-life. Whereas, in North
cut.
America, total shelf-life of several weeks (i.e. at least greater
[0004] The conventional vacuum packaging process nor- than four weeks) is
desired because of distant markets and
mally does not allow the meat cut to exhibit a deep red intent of North
American meat industry to export to distant
pigment desired by retailers and consumers. Subsequently, countries. Hence,
the goal is to extend the shelf-life of
once these vacuum-packed meat cuts reach the supermarkets retail-ready meat
cuts.
or meat distribution centers, the primal cuts are cut into
[0009] A number of approaches have been taken to extend
smaller cuts. These smaller cuts are then repackaged or the shelf-life of
meat. The basic approach is to package meat
displayed in a case for sale. In a very short time, the meat cuts with an
inert gas atmosphere after the meat has been
cuts lose the desired red color and start to brown or other- shipped from a
processing facility to a retail outlet. There-
wise become discolored, losing its aesthetic fresh, healthy alter, when the
retail outlet receives the packaged meat, the
appearance and often not sold as a result. inert gas within the package is
replaced with an oxygen-
[0005] Specifically, meat cuts lose their healthy color due containing
atmosphere.
to metmyoglobin (aka browning of meat). Metmyoglobin [0010] One example of
such a packaging system is
occurs because of oxidation of deoxymyoglobin, and this depicted in U.S.
Pat. No. 4,055,672 issued in 1977. The '672
chemical reaction of the meat is irreversible. Under a patent provides for
a system in which a meat product is
reduced oxygen condition, the rate of the metmyoglobin is packaged with one
of the package walls formed from a gas
high. Transient discoloration can occur in a reduced oxygen impermeable
material and another package wall formed as
environment, because meat muscle possesses a limited enzy- an inner gas
permeable layer and an outer gas impermeable
matic activity known as metmyoglobin reducing activity layer. The meat cut
is initially packaged in an inert gas
(MRA) which converts metmyoglobin back to deoxymet- atmosphere which is
maintained within the package by the
myogjobin However, this process, which can decrease and package walls
including the outer gas impermeable wall
possibly reverse discoloration, takes several days and is layer. If the
outer gas impermeable layer is removed, this
detrimental to centralized meat operations. Furthermore, the enables the
oxygen-containing ambient air to flow into the
MRA is extremely limited and once consumed by the meat package through the
gas permeable layer. However. the '672
cannot be rejuvenated, patent allows the meat to deteriorate
after the impermeable
[0006] Despite the inherent drawback, centralized pack- layer has been
removed, unless an additional impermeable
aging of retail meat cuts is gaining in popularity in the food layer is
added. Nevertheless, placing a gas impermeable film
industry due to its economies and the potential to maintain layer over a
gas permeable film layer is expensive to produce
quality, enhance safety, and extend the shelf-life of fresh and difficult
to seal to a container.
meat. However, the general requirements to optimize shelf- [0011] Another
example of packaging containing an inert
life of centrally prepared retail-ready meat cuts are slightly gas
atmosphere is depicted in U.S. Pat. No. 6,302,324 issued
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in 2001. The '324 patent provides for packaging a food netic south sides.
here, the negative magnetic north sides of
product in a receptacle containing an inert gas atmosphere the magnetic
strips or pads are arranged to impinge on the
and sealing a film to the receptacle. The receptacle includes fresh food
products stored in a low-temperature environ-
a sealing flange and a tab portion extending from the sealing ment.
However, the '105 and '215 patents achieve a wetter
flange to which the film is sealed. The tab and the film are condition
thereby establishing a longer shelf-life condition
removed from the package to form an opening between the for foods which are
stored in a combined environment to
film and the receptacle when the food product is ready to be include a
north magnetic field and a selected low tempera-
displayed to consumers. An atmosphere exchange operation turc.
is carried out through the opening, by inserting a nozzle .-
L0015] Another example of a shelf-life extender for food
through the opening and introducing an oxygen-containing
use is depicted in U.S. Pat. No. 5,985,303 issued to Okada
gas into the receptacle cavity through the opening. The inert
in 1999. The '303 shelf-life extender incorporates an isothio-
gas atmosphere initially contained within the receptacle is
cyanic acid compound being supported on a matrix, where
exhausted through the opening and the nozzle is withdrawn
the compound is packaged in synthetic resin film or non-
from the opening. The opening is closed by sealing the film
woven fabric. However, the '303 patent concentrates on
to the receptacle. The '324 patent allows an inert gas
acidic chemical compounds and gelling agents as opposed to
atmosphere within the interior of the package to be easily
integrating a zero oxygen packaging system as described by
and quickly replaced with an oxygen-containing atmo-
the present invention.
sphere.
[0016] U.S. Pat. No. 6,153,241 describes another method
[0012] U.S. Pat. No. 6,408,598 also provides for a modi-
and a package for extending the shelf-life of a food. Spe-
fied atmosphere packaging process including the steps of
cifically, the method of achieving an extended shelf life for
providing a tray, providing an upper film which includes a
a food includes enclosing the food in a discrete container
sealant layer which is sealable to the tray, orienting the film .
having a first and a second container position, treating the
to an orientation ratio of from about 6.0:1 to about 16.0:1
food in the discrete container with heat in a treatment
positioning, a high profile product on the tray, extending the
chamber while the container maintains the first container
upper film above the tray and product, drawing the upper
position and raising the container to the second container
film into a concavity by differential pressure, maintaining
position under which the container is distributed, sold or
the concave shape of the upper film while heating the film,
used. However, contrary to the present invention, the '241
removing gases from the space between the upper film and
patent describes a method of heat treating a pumpable food
the tray and product, introducing a desirable gas into the i carried out n
a treatment chamber.
space, releasing the upper film such that it shrinks toward the
product and the tray while the desirable gas is retained [0017] U.S. Pat.
No. 6,183,790 to Delducca et al and U.S.
within the space preventing close contact of the film with the Pat. No.
6,666,988 to Carr et al utilize an external oxygen
lowermost portions of the product and sealing the upper film accelerator to
activate an oxygen scavenger to reduce the
to the flange of the tray, wherein at least the step of heating oxygen
concentration to 500 parts-per-million (ppm) within
the film shrinks the film, thereby tensioning it onto and 90 minutes.
However, even at these low oxygen levels
across the underlying product. metmyoglobin formation remains very
high (See FIG. 1).
This stems from the fact that transient discoloration occurs
[0013] Another patent for extending the shelf-life of meat
because of limited metmyoglobin reducing activity (MRA)
has been depicted in the process for pre-packing fresh meat
with the meat muscle, and these patents fail to address this
seen in U.S. Pat. No. 4,683,139. The '139 patent describes
process.
a process where the meat is treated with an aqueous solution
containing three active components, namely phosphate corn- [0018] U.S. Pat.
No. 6,269,946 to Colombo includes use
pounds, a reducing agent and a sequestering agent; and then of a meat tray
over-wrapped with a gas permeable film. This
packaging the meat in a controlled gaseous atmosphere patent uses metal
chloride inside a meat tray to combine with
containing from about 20% to 80% carbon dioxide and from water and acid to
produce chlorine dioxide to help preserve
about 2% to 30% oxygen, with the balance being nitrogen. meat cuts packaged
therein. The disclosed invention also
Specifically, the process includes (1) placing at least one claims oxygen
absorbers packaged within a barrier bag, but
pork chop on each of a plurality of semi-rigid trays; (2) the patent fails
to discuss the importance and advantages of
placing a gaseous mixture over and around the chops on sealing oxygen
scavengers inside the meat tray or the need
each of the trays; (3) sealing the trays with a gas permeable to quickly
obtain a zero-oxygen gas environment for long-
film; (4) placing a plurality of the trays on a thermoformed term cold
storage of meat cuts both within the meat tray and
tray; and (5) covering and sealing the thermoformed tray the barrier (e.g.
master) bag. The patent only provides for
with a gas impermeable film. However, the '130 patent very low oxygen
environment of about less than 0.05%
concentrates on the centralized pre-packing of fresh meats at volume of
oxygen and does not attain zero oxygen levels.
the meat packing plant prior to shipment to the point of Further, the meat
tray adds a receptacle for injecting carbon
storage or retail sale. Further, the '139 patent fails to include dioxide
into the meat tray, and does not recommend a
100% nitrogen gas filling a master bag before the placement nitrogen-rich
gas environment for storage, instead favoring
of the tray. carbon dioxide. Carbon dioxide is not
preferred for several
[0014] Other examples of inventions desiring to extend the reasons.
shelf-life of food products are U.S. Pat. Nos. 5,527,105 and [0019] Other
U.S. Patents and publications (U.S. Pat. Nos.
5,705,215 issued to Riach, Jr. The '105 and '215 patents 6.230,883,
6,447,826, 6,586,651, 6,592,919) recommend
provide for a magnetic method for extending the shelf-life of using an
atmospheric mixture containing carbon dioxide or
food products wherein magnetic strips, matting formed from discuss methods
to create an atmosphere of carbon dioxide.
the strips and pads having magnetic north sides and mag- However, in these
inventions, although carbon dioxide has
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anti-microbial activity, solubility increases at low tempera- However, beef
with poor stability is highly susceptible to
ture and it is absorbed into the meat cuts, and after long metmyoglobin
formation even at very low 02 concentrations
storage the meat starts to discolor from the inside out. For and subzero
temperatures, and these cuts require a zero-
this reason, carbon dioxide is only successful for long-term storage
environment for long-term storage.
storage of primal or sub-primal meat cuts or uncut carcasses.
[0024] If the enzymes causing MRA are retained in the
However, for retail ready cuts, use of carbon dioxide is
meat, longer shelf life of meat cuts is possible. To accom-
detrimental to the meat color if long-shelf life of case-meat
plish this, the oxygen concentration in the master-bags used
is desired. Solublization of carbon dioxide into the meat
to ship meat from a central meat operation containing groups
prevents and/or delays meat cuts from re-blooming when
of meat trays must be zero. Under zero-oxygen concentra-
master bags containing retail meat cuts are opened and the
tion. meat color will go to the de-ox state and will come back
meat exposed to air.
to ox-state with the master-bags containing trays are opened
[0020] In other systems utilizing activated oxygen scav- and exposed to
atmosphere. By doing this procedure, the
engers as mentioned by Delducca et al and Carr et al, the enzymes causing
MRA are retained and the meat does not go
presence of carbon dioxide hinders the rate of oxygen through a transient
discoloration and long shelf-lives can be
absorption by oxygen scavengers due to formation of car- attained. The
present invention has been developed to alle-
boxylic acid (carbon dioxide reacting with residual oxygen), viate the
above-identified drawbacks and provide further
hence the lowest oxygen concentrations obtained with these benefits to the
meat distribution centers, supermarkets and
systems is 500 ppm within 90 minutes, and other issues the consumer.
regarding transient meat discoloration remain unsolved. [0025] The goal
of the invention is to provide meat
packers with an integrated packaging system that incorpo-
[0021] Present commercial centralized meat operations
rates oxygen scavengers along with automatic formation of
employ master packaging in which three or more trays, each
master-bags to fit the size of meat-trays, family size or
containing retail-ready meat cuts, are placed in a gas-
multi-individual trays, and gas-flushing and sealing. The
impermeable master bag. However, residual oxygen may be
packaging system reduces the oxygen concentration to 0
present inside the packages due to the entrapment of oxygen
during controlled atmosphere packaging (CAP). Specifi- ppm within a short
period of time after pack closure. The
invention uses modified horizontal, form, fill, and seal
cally, the residual oxygen may be present due to any one of
the following factors: (1) insufficient oxygen evacuation; (2) equipment
with different packaging size options. The pack-
insufficient flushing times during CAP-machine operations; aging equipment
is intended to operate exclusively in meat
(3) use of an improper ratio of meat-mass to package operations utilizing
oxygen scavengers, but may be adapted
atmosphere resulting in dead space in the master bag; (4) for operations
with long-term storage in a carbon dioxide
oxygen entrapment in the retail trays themselves, in absor-
environment.
bent pads or under the meat cut; (5) oxygen ingress through
SUMMARY OF THE INVENTION
seams of a film used to over-wrap a master pack; (6) film
defects; or (7) oxygen release from meat muscle. Since some [0026] The
present invention in its several disclosed
of these factors are inevitable in commercial meat packaging embodiments
alleviates the drawbacks described above with
operations, the plain use of master packaging has found respect to
traditional meat packaging and incorporates sev-
limited application in commercial centralized meat opera- eral additionally
beneficial features. The process of packag-
tions. Therefore, a system is needed to reduce the oxygen ing meat, namely
retail-ready meat, is known in the prior art.
concentration in a relatively short period of time in order to Disclosed
herein is a packaging system and method of same
restore the metmyoglobin reducing activity, developed to prevent meat
discoloration of prepared fresh
[0022] Previously issued patents and prior art procedures meat cuts, such
as beef, pork, lamb, and chicken. Specifi-
reduce the oxygen concentration to at best 500 ppm within cally, different
packaging configurations use self-activated
oxygen scavengers and structures to extend the shelf life of
90 minutes. These processes can result in some extension of
shelf life of case-ready meat cuts for retail sale, however fresh meat cuts
by attaining a zero oxygen-packaged envi-
ronment.
these oxygen concentrations still lead to transient meat
disclosure. For meat-packaging implementing national and [0027] When fresh
meat is exposed to oxygen, two effects
international centralized meat packing operations, extremely normally
occur. First, bacteria begins to grow and subse-
long shelf life in the range of 8-10 weeks is desired. This quently the
fresh meat color disappears. By eliminating
long of a shelf-life can only be obtained if the transient meat exposing
the meat to oxygen, the chances of reducing
discoloration can be avoided. Consequently, premature tern- bacteria and
extending the fresh meat color improve dra-
poraxy discoloration limits the advantages of centrally pack- matically. As
a result, the present invention effectively
aged retail ready meat cuts using current oxygen depleted removes oxygen
very rapidly from a sealed package thereby
master packaging methods because a zero-oxygen storage increasing the shelf-
life of the meat up to 12 weeks or more
environment is not attained, for different meat types.
[0023] Discoloration is also dependent on the specific [0028] The disclosed
packaging system extends the shelf-
muscle packaged since tissue vary in capacity to withstand life of
centrally prepared retail-ready meat cuts by restoring
low oxygen concentrations (<500 ppm). Centrally prepared metmyoglobin
reducing activity of the meat-muscle through
beefsteaks and ground beef packaged under controlled atmo- zero oxygen
packaging. This achieves extremely long shelf-
spheres are shown to be susceptible to very low oxygen life for storage of
retail-ready meat cuts. A retail-ready meat
concentrations. Beef muscle with high color stability are cut is placed in
a tray having an activated oxygen scavenger
least susceptible to metmyoglobin formation if the atmo- based upon an iron
chemical system and an absorbent pad.
sphere is maintained at <600 ppm 02 at temperatures <0 C. Several of these
trays are placed in a master bag that is filled
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with a high nitrogen gas mixture and sealed. Several differ- bags and meat
packages to between 0.6 and 2.0 hours. The
ent combinations of placing scavengers (based upon iron master bags are
formed around the meat trays and the
chemical systems) and optimization of the oxygen scaveng- ambient air is
flushed from the bag. The bag is then injected
ing capacity in each tray are achieved, with the desired gas mixture
environment that is preferably
100% nitrogen or nitrogen rich (>50%) with the balance a
[0029] The tray or the master bag containing optimum mixture of other
gases, preferably carbon monoxide and
oxygen scavenging capacity results in 0.6-2.0 hour half-life carbon
dioxide. Some small quantity of carbon monoxide
for oxygen in the master bag (depending upon the initial (>0.1%) is
preferred. The master bags can then be stored for
oxygen concentration and meat-type) and is the one desired several weeks at
freezing or below freezing temperatures
for centrally prepared retail-ready meat cuts. Such a pack- (28 -32 F.)
until needed for placing into a retail display for
aging system under 100% nitrogen atmosphere resulted in at several days
before meat discoloration occurs.
least a ten week storage life for centrally prepared meat cuts,
such as beef tender loin steaks, with a subsequent display
DESCRIPTION OF THE DRAWINGS
life of at least three days.
[0035] lhe objects and features of the invention will
[0030] Thus, the use of an activated oxygen scavenger and
become more readily understood from the following detailed
an absorbent pad inside a master bag having 100% nitrogen
description and appended claims when read in conjunction
introduced therein provides a significant increase in profits
with the accompanying drawings in which like numerals
by reducing spoilage. By reducing the partial pressure of
oxygen to zero ppm in the master bags, the growth of the represent like
elements and in which:
aerobic spoilage and pathogenic microorganisms is inhibited [0036] FIG. 1
is a x-y graph depicting the influence of
thereby extending the storage and display life of retail-ready oxygen
partial pressure on three chemical states of myoglo-
fresh meat packages. Additionally, this process preserves the bin;
vivid, bright cherry red color of red meats, whereby longer
shelf life and better looking meat products translate into [0037] FIG. 1A
is a table displaying the half-life of
higher sales and higher profits. Moreover, the master pack- oxygen in bags
containing scavengers based upon enzymes
age will reduce purge due to temperature changes and will and iron chemical
systems in an air or nitrogen atmosphere
actually enhance the natural aging process producing more as described in
Example 1;
flavorful and tender cuts of fresh meat.
[0038] FIG. 18 is a table showing constants of first order
[0031] Another advantage of the present invention is that kinetics equation
for various scavengers;
a retailer is capable of unpackaging a days' supply of fresh
[0039] FIG. 2A is a table describing treatments for beef
meat cuts at a time. The master package is protected from
steaks and pork chops as described in Example 2;
oxygen exposure until the seal is released and the individual
packages are placed in the retail case. In essence, the shelf [0040] FIG.
2B is a table depicting oxygen concentration
life clock does not begin ticking until the fresh meat is in master packs
containing beef and pork stored at 2 C. in
placed in the retail case. For central packaging operations, 100% nitrogen
atmosphere over the course of seven days as
by utilizing the master packages, the shrinking of meat cuts described in
Example 2;
due to handling, transportation and temperature fluctuations
is greatly reduced to virtually zero shrinkage. [0041] FIG. 2C is a table
displaying mean color, surface
discoloration and retail appearance scores and standard
[0032] The main advantage of the invention is the zero- errors for pork
chops and beef steaks after various treat-
oxygen system gas environment in the master bag stops the ments;
tbnnation of metmyoglobin, the agent that causes fresh meat
to become discolored. By stopping metniyoglobins forma- [0042] FIG. 2D is a
table depicting mean values of the
tion, the metmyoglobin reducing activity (MRA) of the meat chemical states
of myoglobin (% met-, % deoxy-, and %
muscle is retained. Because the oxygen concentration in the oxy-myoglobin)
and standard errors of difference for pork
master bag is zero ppm, metmyoglobin cannot form and the chops and beef
steaks after various treatments:
discoloration process never occurs. Further, under the zero-
[0043] FIG. 2E is an x-y graph depicting a discoloration
oxygen system, only lactic acid and other slow growing
anaerobic bacteria will grow; and the growth of faster score given to bags
undergoing various treatments as
growing aerobic bacteria causing rapid spoilage is restricted, described in
Example 2;
[0044] FIG. 2F is an x-y graph depicting a retail appear-
[0033] Shelf-life in the retail case is increased by one to
seven additional days, depending upon the type of meat cut. ance score
given to bags undergoing various treatments as
The present packaging system preserves the enzymatic described in Example
2;
activities of meat-muscle that maintains the bright cherry red [0045] FIG.
2G is an x-y graph showing different treat-
color of each meat cut, the retail display life of the meat is ments given
a discoloration score during retail display times
extended dramatically. The addition of carbon monoxide as as described in
Example 2;
part of the gas mixture environment also helps preserve the
reddish color of the meat as a layer of carbon monoxymyo- [0046] FIG. 211
is an x-y graph illustrating different
globin is formed on the meat surface, treatments given a retail appearance
score during retail
display times as described in Example 2;
[0034] The apparatus used in the invention will automati-
cally package meat trays into a single master bag containing [0047] FIG. 21
is an x-y graph showing different treat-
oxygen scavengers with appropriate oxygen absorption ments having a certain
percentages of metmyoglobin during
capacity to reduce the half-life of oxygen inside the master retail display
times as described in Example 2;
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[0048] FIG. 3A is an x-y graph depicting a control and [0066] FIG. 5J is an
x-y graph showing color scores of
two experimental types given a discoloration score within meat, namely lamb
chops in foam trays, based on time of
storage intervals as described in Example 3; retail display as described in
Example 5;
[0049] FIG. 38 is an x-y graph illustrating the control and [0067] FIG. 6A
is an x-y graph showing color score of
two experimental types given a retail appearance score meat, namely pork
chops, based on time of retail display
within storage intervals as described in Example 3; over a period of time
as described in Example 6;
[0050] FIG. 3C is an x-y graph illustrating the control and [0068] FIG. 6B
is an x-y graph showing discoloration of
two experimental types having a percentage of metmyoglo- meat, namely pork
chops, based on time of retail display as
bin taken during storage intervals as described in Example described in
Example 6:
3; [0069] FIG. 6C is an x-y graph
depicting scores of retail
[0051] FIG. 4A is an x-y graph showing different weeks appearance of meat,
namely pork chops based on time of
receiving color scores during retail display times as retail display as
described in Example 6;
described in Example 4;
[0070] FIG. 6D is an x-y graph showing scores of off-odor
[0052] FIG. 40 is an x-y graph showing different weeks intensity of meat,
namely pork chops, based on the time of
receiving discoloration scores during retail display times as retail
display as described in Example 6;
described in Example 4;
[0071] FIG. 6E is an x-y graph detailing odor acceptabil-
[0053] FIG. 4C is an x-y graph showing different weeks ity of meat, namely
pork chops, based on the amount of time
receiving retail appearance scores during retail display times the chops
are displayed as described in Example 6;
as described in Example 4;
[0072] FIG. 6F is an x-y graph depicting microbial plate
[0054] FIG. 4D is an x-y graph showing different weeks count for meats,
namely pork chops, based on time the chops
receiving off odor intensity scores during a course of days of are
displayed as described in Example 6;
retail display as described in Example 4;
[0073] FIG. 7 is a schematic flow chart showing the
[0055] FIG. 4E is an x-y graph showing different weeks method of the
process used for packaging meat under the
receiving odor acceptability scores during a course of days invention;
of retail display as described in Example 4;
[0074] FIG. 8 is an embodiment of the arrangement of the
[0056] FIG. 4F is an x-y graph depicting different weeks elements of a meat
tray;
showing a microbial count during a course of days of retail
display as described in Example 4; [0075] FIG. 9 is another embodiment of
the arrangement
of the elements of a meat tray;
[0057] FIG. 5A is an x-y graph depicting a microbial plate
[0076] FIG. 10 is an embodiment of the arrangement of
count for meats, namely lamb chops stored on foam trays
meat trays inside a master bag;
over a period of time as described in Example 5;
[0058] FIG. 5B is an x-y graph illustrating microbial plate [0077] FIG. 11
is an embodiment of a master bag con-
count for meats, namely lamb chops stored on plastic trays taming a large
primal or sub-primal meat cut;
over a period of time as described in Example 5; [0078] FIG. 12 is another
embodiment of the arrangement
of meat trays and oxygen scavengers inside a master bag;
[0059] FIG. SC-I to 5C-I1 is an x-y graph detailing odor
and
acceptability of meat, namely lamb chops, based on the
amount of time the chops are displayed as described in [0079] FIG. 13 is a
schematic drawing of an apparatus to
Example 5; package meat according to the disclosed
method and pro-
[0060] FIG. SD-I and 5D-I1 is an x-y graph showing cess.
scores of off-odor intensity based on the amount of time the
DETAILED DESCRIPTION OF THE
chops are displayed as described in Example 5;
PREFERRED EMBODIMENTS
[0061] FIG. 5E is an x-y graph depicting scores of retail
room] As required, detailed embodiments of the present
appearance of meat, namely lamb chops based on time of [
retail display in plastic trays as described in Example 5; invention are
disclosed herein; however, it is to be under-
stood that the disclosed embodiment(s) are merely exem-
[0062] FIG. 5F is an x-y graph depicting scores of retail plary of the
invention that may be embodied in various and
appearance of meat, namely lamb chops based on time of alternative forms.
Specific structural and functional details
retail display in foam trays as described in Example 5; disclosed herein
are not to be interpreted as limiting, but
[0063] FIG. 5G is an x-y graph illustrating surface dis- merely as a basis
for the claims and as a representative basis
coloration of meat, namely lamb chops in plastic trays based for teaching
one skilled in the art to variously employ the
on time of retail display as described in Example 5; present invention.
Further, the particular materials and
amounts thereof, as well as other conditions and details,
[0064] FIG. 5H is an x-y graph detailing surface discol- recited in these
examples should not be used to unduly limit
oration of meat, namely lamb chops, in foam trays based on this invention.
time of retail display as described in Example 5;
[0081] The present invention in its several disclosed
[0065] FIG. 51 is an x-y graph showing color scores of embodiments
alleviates the drawbacks described above with
meat, namely lamb chops in plastic trays, based on time of respect to
traditional meat packaging and incorporates sev-
retail display as described in Example 5; eral additionally beneficial
features. The process of packag-
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ing meat, namely retail-ready meat, is known in the prior art. tray
overwrap consisted of additional ambient atmosphere
Disclosed herein is a packaging system and method of the flow with multiple
holes, each having a diameter of less than
same developed to prevent meat discoloration of prepared 5 mm, punched
through the overwrap or a single needle hole
fresh meat cuts, such as beef, pork, lamb, and chicken. with a diameter of
less than 5 mm.
Specifically, different packaging configurations of compo-
Master Bag Characteristic
nents of the system use self-activated oxygen scavengers
and structures to extend the shelf life of fresh meat cuts. A [0086] The
meat trays containing different meat cuts in
number of different options have been tested. different numbers (one to six
retail trays) are placed in a
Oxygen Scavengers master bag possessing good seal
strength. The master bag
possesses good seal strength with either a foil lining or an
[0082] Oxygen scavengers based on iron chemical sys- ethyl vinyl alcohol
(EVOH) lining. The oxygen permeability
tems were employed. A sachet placed within the packaging of the master bag
was less than 13 cc of oxygen per square
bag contains chemical granules ranging from 0.001 mm to meter per 24 hours
at 73 F. and 70% relative humidity. The
1.5 mm in diameter. The half-life of oxygen in a bag master bag was gas-
flushed with different gas-compositions
containing these oxygen scavengers was in the range of 30 and sealed.
to 1500 minutes, with the quantity of oxygen absorption
[0087] The modified atmosphere characteristics were
material ranging from 1 gram to 300 grams. The oxygen
composed of different gas mixtures of carbon dioxide,
absorption material was placed in a package, which was
carbon monoxide, and nitrogen/inert gas. Typical gas mix-
either laminated or unlaminated with porosity levels ranging
tures either consisted of 100% nitrogen and/or any inert gas
from 20 to 120 gurly a second, and an active surface area of
or contained 100% carbon dioxide or different percentages
4 to 64 square inches. The preferred material for the bag is
of gases generally in the concentrations of <1% carbon
tyvek. The scavengers are typically formed from iron
monoxide, <40% carbon dioxide, and the balance either
(<25%, preferably 15-20%), carbon (<35%, preferably
nitrogen and/or some other inert gas. The oxygen scavengers
20-30%), vermiculite (<20%, preferably 10-15%), and de-
of different characteristics were placed in the master bags or
ionized water (<10%, preferably 5%), salt [NaCI] (<10%,
preferably 5%). A small amount (<10%) of zeolites can also in the retail
trays or both. The residual oxygen content in the
be added for increased oxygen absorption rates. Oxygen master bag after gas
flushing using single or multiple cycles
was less than 6%. The storage temperature of the master
scavengers can also be based on magnesium, copper, and
enzymes. The oxygen scavengers are activated upon expo-
bags was less than 40 F., and the master bags were stored
sure to air and/or oxygen in an atmosphere greater than 60% for up to 15
weeks.
relative humidity, and work under a temperature range of Display and
Sampling of Retail-Trays
28 to 45 F.
[0088] Upon removal from primary storage at weekly
Meat Characteristics intervals, and on day 0 of retail
display, master packaging
was removed and retail trays placed in the center of the
[0083] The meat can be of any type such as pork, lamb,
beef, veal, chicken, fish, turkey, venison, or any other meat display
shelf. The displayed meat cuts were examined for
discoloration, retail acceptability, off odor intensity, and
type. In the actual meats studied developing the invention,
odor acceptability, and odor description for every 24 hours
meats used included beef, veal, pork, lamb, and chicken. The
for up to nine days. A similar procedure was repeated for all
cuts used were primal and/or sub-primal, and the grades of
fresh meat cuts were prime, choice, and/or select. The meats storage
intervals for up to 15 weeks.
included both boned and boneless cuts, and the size of fresh Visual
Assessment of Master-Packaged Meat Cuts
cut meat product was in the range of 1 to 5 lbs. The meat
[0089] A five-member panel was used for the subjective
carcass was cooled either though blast cooling and/or cold
evaluation of the meat cuts. Surface discoloration was
room storage, with a cooling temperature of between 5 to
evaluated using a seven-point descriptive scale: 1..0%
40 E The time between slaughter and packaging was in the
range of 24 hours to 120 hours. Packaging temperatures (none), 2-1-10%, 3-
11-25%, 4..26-50%, 5-51-75%, 6..76-
were less than 40 F.
99%, 7-100%. Retail appearance was assessed on a seven-
point hedonic scale: 1-Extremely undesirable, 2-undesir-
Retail Tray Characteristics able, 3-Slightly undesirable, 4-Neither
desirable nor
[0084] The retail tray composition was of plastic and/or
undesirable. 5-Slightly undesirable, 6-Desirable, and 7=Ex-
polystyrene and/or combination of both. The inherent oxy-
tremely desirable.
gen content of the retail tray was in the range of 10 to 23,000 Odor
Assessment of Master-Packaged Meat Cuts
ppm. The surface of the retail tray exhibited either a grid or
L0090] A five-member panel was used for odor assess-
ridged pattern, or a flat surface upon which to place the fresh
ment. Off odor intensity scores were assessed using a
meat product. The retail tray cover was either lidded or
four-point descriptive scale: 1-No off odor, 2-Slight off
over-wrapped. The retail tray surface area was in the range
of 15,000 to 325,000 square mm. A moisture absorbent pad odor, 3-Moderate
off odor, 4-Prevalent off odor. Odor
acceptability scores were assessed using a five-point scale:
was either placed in the retail tray before the fresh meat
1-Acceptable, 2-Slightly acceptable, 3-Neither acceptable
product or was not included. The oxygen scavenger pads
no unacceptable, 4-Slightly unacceptable, 5-Unacceptable.
were placed in the retail tray or exterior to the retail tray.
[0085] The retail tray overwrap used has an oxygen per-
Microbial Analysis
meability in the range of 3,000 to 10,000 cc of oxygen per [0091] A 10 cm'
sample was obtained at each sampling
square meter per 24 hours at 73 F. and 70% relative time (on day 0 and
last day of each storage interval) from
humidity. Additional atmospheric permeability of the retail each meat cut
using a sterile cork borer. The sample was the
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placed into a stomacher bag with 10 mL of 0.1% peptone as an oxygen barrier
under sub-zero temperatures and low
solution and was massaged for 120 seconds using a corn- oxygen
concentrations. Thus, the first phase of the invention
mercial stomacher, yielding a dilution of 10 . The homogen- concentrates on
the placement of oxygen scavengers posi-
tate was further diluted 10-, 100-, and 10,000-, and 100, tioned inside the
tray and being surrounded by the packaging
000-Ibld, after which 0.1 mI. volumes of undiluted film.
homogenate. Each dilution prepared was spread on duplicate
[0100] In the second phase as illustrated in Example 2, the
plates of All Purpose Tween (APT). The plates were then
scavengers were interiorly placed within the trays containing
incubated aerobically for 3 days at 25 C. The micro flora
meat muscles. Here, the meat muscles had poor color
was determined from plates bearing 20-200 colonies,
stability since the packaging films covering the trays (seen
Results Summary in Example 1) act as oxygen barriers
under sub-zero tem-
peratures and low oxygen concentrations. Hence, the pres-
[0092] The oxygen concentration was 0 ppm (zero) after ence of 02
scavengers of appropriate capacity (at least 10 cc
24 hours of storage, and was 0 ppm throughout the storage per pound of
meet) is required. During the second phase,
period of up to 15 weeks. Based on sensory and microbial several
experiments concentrated on the effect of varying the
analysis: oxygen-absorbing capacities on the
display life. Further, the
[0093] 1) beef cuts were acceptable for 10 weeks storage need for knowing
the initial concentration of oxygen in the
plus 5 days at the retail display, package, calculating the needed half-
life of oxygen in the
package and subsequently designing the oxygen scavenger
[0094] 2) pork chops were acceptable for 15 weeks during required to obtain
the desired half life of oxygen.
storage plus 9 days at the retail display,
[0101] Example 3 depicts the third phase of the present
[0095] 3) lamb chops were acceptable for 8 weeks during invention whereby
preventing transient discoloration of the
storage plus 7 days at the retail display, and meat cuts, namely the retail-
ready meat cuts. Lastly, the
fourth phase as shown in Example 4 shows that the resto-
ration 4) chicken pieces were acceptable for 8 weeks
ration of metmyoglobin reducing activity will result in
storage plus 6 days at the retail display.
extending the shelf-life of retail ready meat cuts. For
Discussion example, the shelf-life of the retail-
ready beef tender loin
cuts was ten weeks with a display life of three days after
[0097] Referring to FIG. 1, there are three chemical states
each weekly storage differing from the conventional one to
for myoglobin. Metmyoglobin is at a peak level at low
two weeks with a display life of one and half days.
oxygen pressures of about 2 mm of mercury. At sea-level,
the atmospheric pressure of oxygen is approximately 160
EXAMPLE 1
mm of mercury, while the total atmospheric pressure is
approximately 760 mm of mercury. As can be observed
Oxygen Absorption Kinetics of Enzymatic and Iron
graphically, in order to begin minimizing formation of
Chemical Systems Based Oxygen Scavengers
metmyoglobin, the atmospheric partial pressure needs to be
reduced to less than 1 mm of mercury, or an oxygen content [0102] The
current uses of 02 scavengers generally
at sea level of less than 0.13%. To have no metmyoglobin involve packs in
which the atmosphere contains some sub-
formation, the atmospheric partial pressure of oxygen needs stantial
fraction of 02, if not air, at the time of pack sealing
to be reduced to 0 rum mercury for an 02 content at sea-level and the
inhibition of chemical reactions or proliferation of
of 0 ppm (e.g. zero oxygen). microorganisms that proceed relatively
slowly. Conse-
[0098] Example 1 shown in Table IA depicts the first quently, commercial 02
scavengers are designed to remove
a specified amount of 02 from a relative high 02 atmosphere
phase of the present invention involving a detailed oxygen
over periods of a day or more. 'The rate of 02 absorption has
absorption study of oxygen scavengers based upon an iron
then not been a principal concern in the design of commer-
chemical system and enzymatic activity. The iron chemical
cial 02 scavengers. However, there are applications such as
system based scavengers are dependent upon the chemical
centralized meat operations where the rate of 0, absorption
reaction of ferrous iron to ferric oxide or ferric hydroxide.
is of prime importance.
Specifically, Example 1 indicates that oxygen scavengers
modified based upon the iron chemical system have the [0103] The 02
absorption rates of 02 scavengers vary with
potential for reducing the oxygen concentration to 0 ppm the natures of
their reactants and other materials used in their
within a few hours of master packaging, provided an appro- construction.
Rates of absorption may also be affected by
priate selection of oxygen scavengers is combined with factors such as
temperature and the compositions of the
appropriate placement in the package. atmospheres to which they are
exposed. Therefore, the
objective of this study was to design an oxygen scavenger
[0099] Two factors restricting the activity of the oxygen
for centralized meat operation after studying the 02 absorp-
scavengers are sub-zero temperatures such as ¨1.5 C. and
tion kinetics of 02 scavengers based upon enzymes and iron
a low oxygen concentration. Thus, the rate of the iron
chemical systems.
chemical reaction is greatly reduced at subzero tempera-
tures, and low oxygen concentrations prevent random move- Materials and
Methods
ment of oxygen molecules due to diffusion, which results in
[0104] 1. 02 Scavengers
lower oxygen absorption rates. Therefore, the activation of
a custom-designed oxygen scavenger of an appropriate [0105] Self-activated
02 scavengers based upon iron
capacity is capable of yielding short half-life of oxygen, i.e. chemical
systems and enzymes were manufactured. Since
a high rate of oxygen absorption. Furthermore, the packag- scavengers based
upon iron chemical system may form
ing film, preferably having a high oxygen permeability, acts carboxylic
acid in the presence of CO, atmosphere, nitrogen
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atmosphere should only be used to obtain maximum oxygen calculating the
volumes of 02 absorbed from each atmo-
absorption rates from these scavengers, sphere of air by the scavenger, the
initial volume of air was
taken to be the 240 mL added to the pack plus the measured
[0106] 2. Absorption of 02 by Scavengers
volume of residual air. The volume of 02 in a pack at the end
[0107] 02 scavengers were placed in gas impermeable of any period was
calculated as the volume of atmosphere at
bags composed of a laminate of polyester, oriented nylon, the end of the
period multiplied by the concentration of 02
and an EVOH/EVA co extrusion with an 02 transmission in the atmosphere at
that time. The volume of atmosphere at
rate of 0.55 nil.. per m2 per 24 hours at 23 C., 70% relative the
beginning of each period was taken to be the volume of
humidity. Bags containing scavengers were either emptied atmosphere at the
beginning of the previous period less the
of air by flattening each bag around the scavengers it volume of the
atmosphere removed as a sample at the end of
contained, or were evacuated then filled with a known the period and the
volume of 02 calculated to have been
volume of N2 or CO2, using a controlled atmosphere pack- absorbed during
the previous period.
aging (CAP) machine, before being sealed. Then, a quantity
[0113] The volume of 02 absorbed during a period was
of air was injected into each bag using a gas-tight syringe
calculated as the volume of atmosphere at the start of the
inserted through a stick-on septum (Modem Controls, Inc.,
previous period multiplied by the concentration of 02 in the
Minneapolis, Minn., USA).
atmosphere at the beginning of the period less the volume of
[0108] Immediately after the injection of air, the puncture- atmosphere at
the start of the period multiplied by the
point was sealed using a hot iron. Each filled bag was stored concentration
of 02 at the end of the period. In calculating
at room or a constant temperature. Samples (8 mL) of the the volumes of 02
remained in the pack in atmospheres of
atmosphere in each bag were obtained every hour for 8 hours N2 or CO2 to
which air was added, the volumes of the
by means of a gas tight syringe inserted through a stick-on atmosphere
removed during sampling and the volumes of 02
septum. If no substantial 02 absorption was noticed within absorbed during
a period were neglected.
8 hours, samples were taken after every 12 hours for up to
[0114] To determine the order of reaction, plots were
96 hours. Immediately after each sampling, the 02 concen-
prepared of the natural logs (In) and the reciprocals of the
tration in the sample was determined using an 02 analyzer
volumes of 02 remaining in the pack atmosphere against
(Mocon MS0750, Modem Controls, Inc., Minneapolis,
time. If the In plot approximated a straight line, the reaction
Minn., USA) with a zirconium oxide sensor, and the punc-
ture-point
regarded as first order. If the reciprocal plot approxi-
mated was then sealed using a hot iron. Residual air in
mated a straight line, the reaction was regarded as second
the emptied bag was measured as the volume of water
order. Rate-constants were calculated using the following
displaced by the emptied bag, and was used in the calcula-
equations:
tion.
[0109] To examine the effects of temperature and initial
02 concentrations on 02 absorption rates, scavengers were for first-order
reactions-144k = ¨ki 4- In[A]o ¨ and
placed in bags after the scavengers, in their original sealed
package, had been held overnight at the temperature at for second-order
reactions¨t= k +
[A
which 02 absorption was to be measured. For each of the
two scavengers at each temperature, six bags were prepared.
Three of the bags were emptied of air, and sealed, and then
[0115] where, [Allid t..amount of reactant A at time t(h),
240 inL of air was injected into each. The other three were
each filled with 4.5 L of N2 before being sealed, and then 15 [0116] k-the
rate-constant (hour), and
mL of air was injected into each. For each of the two
scavenger types based upon scavenging mechanism, two [0117] [A]o=the
initial amount of reactant.
sets of six bags were prepared, with one set being stored at [0118]
Frequency factors and activation energies were
each of the temperatures 25, 12, 2 or -1.5 C. calculated from the
Arrhenius Equation of the form:
[0110] To characterize 02 absorption when 02 scavengers
were placed inside over-wrapped retail trays within master
packs, a 216x133x25 mm (LxWxH) retail tray over- inik) In(A)
R T
wrapped with a film of 02 transmission rate of 8000 mL per
m2 per 24 hours at 23 C., 70% relative humidity, containing
scavengers, based upon iron chemical system, was placed in
each of the six bags. AS mm hole was made at one comer [0119] where,
of the over-wrapped film to allow free exchange of atmo- [0120] A-frequency
factor (frequency of collisions),
spheres during gas flushing, three bags were emptied of air
.=
and sealed, and then 240 la of air was injected into each. [0121]
Eactivation energy (J
The other three bags were each filled with 4.5 L of N2 to [0122] It-
universal gas constant (8.314 J mor 1 K-1), and
which 15 mL of air was added by injection.
[0123] T.temperature (K).
[0111] 3. Data Analysis
[0124] 4. Results p Using scavengers based upon iron
[0112] The half-life of 02 in a pack atmosphere was chemical system in bags
containing air, the 02 half-life was
calculated as the time required for the 02 concentration in four times
longer at -1.5 C. than at 25 C., but with a N2
the pack atmosphere to be reduced to half the initial value, atmosphere,
the 02 half-life at -1.5 C. was only double that
The half-life was calculated from the volumes of 02 at at 25 C. (Table IA)
The 02 half-life in bags containing air
successive time intervals during the storage of the pack. In and scavengers
based upon enzymes was seven times longer
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9
at ¨1.5 C. than at 25 C., but was only two and a half times [0131] 2.
Master Packaging and Storage of Steaks and
longer at ¨1.5 C. than at 25 C. with a N2 atmosphere. Chops
(Table 1A) The 02 absorption reaction was first order for all
[0132] Experiment 1: Ten fresh beef tenderloins (psoas
the 02 scavengers. (Table 1B)
major, PM) and twenty fresh pork loins (longissimus dorsi,
Discussion LD) from animals slaughtered 24 hours
previously, at local
commercial beef-and pork-abattoirs, respectively, were
[0125] The 02 concentrations affected the 02 half-lives
obtained. The meat cuts were vacuum-packaged and stored
substantially for any scavenger type resulting in longer 02
at 2 C. for 14 to 21 days and then used in the experiments.
half-lives for the low initial 02 concentration of 500 ppm in
A total of 39 steaks and 39 pork chops were prepared from
N, atmospheres than for the high initial 02 concentration of
the stored samples.
200,000 ppm in air at the same temperature. Scavengers
based upon iron chemical systems have shorter 02 half-lives [0133] Each
steak or pork chop was placed on a solid
than the scavengers based upon enzymes. The kinetic data of polystyrene
tray with dimensions of 21 6x 1 33x25 mm
the present study showed that the 02 absorption reaction was (LxWxH)
containing 02 scavengers with 02 absorbing
first-order at both high (20%) and low (500 ppm) initial 02 capacity of at
least 10 mL per pound of meat and a single
concentrations and included 02 concentration as a limiting absorbent pad.
Each retail tray was lidded with a shrinkable
factor. film with an 02 transmission rate of
8000 mL per ni2 per 24
hours at 23 C., 70% relative humidity, using commercial
[0126] At high initial 02 concentration, other t'actors, such
glue. Two 3 mm holes were burned through the film in
as the scavenger surface area and environment, may also
opposite corners of each tray using a soldering iron to allow
affect the 02 absorption rates. However, at low initial 02
free exchange of atmospheres during gas flushing. Three
concentrations a diffusion-phenomenon, which is a deriva- retail trays were
placed on a plastic cafeteria tray, which as
live of 02 concentration, was the dominant influence and
then placed in a 595x447 mm (LxW) bi-metalized, plastic
resulted in low 02 absorption. A threshold 02 concentration laminate bag
with an 02 transmission rate of 0.55 m2 per 24
existed where there was a dramatic decrease in 02 absorp- hours at 23 C.,
70% relative humidity. The bag was then
lion rate and 02 concentration became the primary limiting
evacuated, filled with 2.5 L of N,, and heat-sealed using a
factor for the 02 absorption rate. Consequently, different
controlled atmosphere packaging (CAP) machine. Twelve
rate-constants were observed for the same 02 absorption
master packs each containing three steaks or three pork
curve at the same temperature, depending upon initial 02
chops, were prepared and randomly allocated within species
concentration. Therefore, the overall 0, absorption curve
to different treatments including treatments where scaven-
, produced by the scavenger was bi-phasic.
gcrs were placed either in retail trays or in the master
[0127] The effect of the positioning of scavengers within package (Table
2a). Three retail trays containing steaks or
packs was also substantial which suggests that despite its pork chops were
not stored and served as controls.
high 02 permeability, the barrier film acted as an 02 barrier
[0134] Master-packaged steaks and pork chops were
at low 02 concentrations. Additionally, its barrier effect may
stored at 2 C. for one week. The 02 concentration in each
increase with decreasing temperature. Consequently, the
master pack was then measured. The retail trays were then
size of the hole in the lidding film is likely the limiting factor
placed on retail display and evaluated for visual character-
for 02 absorption when retail trays were placed in a bag.
istics by a 4-member trained sensory panel
[0128] Due to significant variation in 02 absorption rates
[0135] Experiment 2: Twenty-five beef rib-eyes (longissi-
of 02 scavengers based upon iron chemical systems and
mus thoracis, LT) from animals slaughtered 24 hours pre-
enzymes, appropriate selection of 02 scavengers is of impor-
viously were obtained from a local commercial beef-abattoir
tance in situations where high 02 absorption is initially
and were vacuum-packaged and stored at 2 C. Following
required. For centralized meat operations, scavengers based storage for 3
weeks, steaks (96, 2 cm thick) were placed in
upon iron chemical system should be employed. Also, total
solid polyethylene trays with dimensions of 216x133x25
oxygen absorbing capacity of these oxygen scavengers
mm containing 02 scavengers with 02 absorbing capacity of
should be such that resulting oxygen half-life is less than two
at least 10 ml. per pound of meat underneath an absorbent
hours. However, due to significant positioning effects, they
pad. Retail trays were lidded with a shrinkable permeable
should be placed either inside the retail trays containing 02
film and were prepared as in Experiment 1. Four retail trays
sensitive products, inside the retail trays as well as in the
were placed on a cafeteria tray, which in turn was placed into
surrounding gas-impermeable bags, or outside the retail tray
a master-pack bag. The master-pack bags were evacuated,
depending on the oxygen sensitivity of the meat cut.
filled with 3.25 L of N2, and heat-sealed using the CAP
machine. Six such packs were prepared containing one of
EXAMPLE 2
four treatment combinations (G, II; Table 2a) and G2 and 112
(not given in Table 2a), which were over-wrapped instead of
Testing of Different Master Packaging Options for lidded. Please note
treatments, G2 and H2, differ from other
Centralized Meat Operations treatments (G and H), by having retail
trays over-wrapped
Materials and Methods instead of lidded. The master-packs
were stored and evalu-
ated using procedures similar to those used in Experiment 1.
[0129] 1. Oxygen (02) Scavengers
[0136] Experiment 3: Twenty-five Beef tenderloins (psoas
[0130] 02 scavengers, based on iron-chemical systems, major, PM) from
animals slaughtered 24 hours previously
were used. These scavengers require moisture for activation were obtained
from a local commercial beef-abattoir. Steaks
and operating in air of N, atmospheres but not in CO, (2 cm thick) were
placed in 216x133x25 turn-solid poly-
atmospheres. ethylene trays containing 02 scavengers
with 02 absorbing
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capacity of 200 mL (S2), 400 mL (S4), 600 mL (S6), or 800 [0146] b. Visual
Properties
m1, (S8) underneath an absorbent pad. Each retail tray was
over-wrapped with a highly 02 permeable and shrinkable [0147] Pork
color scores in all treatments ranged from 2.4
to 3.3, and would be considered normal except in treatment
film as previously described. Containing the same treatment
Dl, where the chops were slightly pale. (Table 2c) Chops in
combination (S2, S4, S6, or 58), four retail trays were placed
all treatments could be considered to be without discolora-
in a master pack, which was evacuated, filled with 4.5 L of .
tton, except in treatments A and B, where the chops were
N2, and heat-sealed using the CAP machine. Three retail
slightly discolored. Chops in all treatments were rated
trays served as un-stored controls.
desirable to extremely desirable except in treatments A, B,
[0137] Following one week of storage at ¨1.5 C., the 02 and DI. Chops in
treatment A were rated slightly undesirable
concentration in each master pack was measured as previ- and chops in
treatments 13 and DI were rated slightly
ously described. All master bags were removed and the retail desirable.
(Table 2c) Beef steaks in all treatments were
trays were placed on retail display and evaluated for visual perceived to
be bright cherry red to moderately dark red,
characteristics daily tbr four days. except in treatments E and GI, where
color scores were
reduced due to complete discoloration of one or more steaks.
[0138] 3. Display and Evaluation of Retail Trays Steaks in all treatments
without 02 scavengers either inside
[0139] All retail trays were placed at the center of the the retail tray or
in the master pack were moderately
discolored. Steaks in treatments H and G1 were also mod-
display shelf. Displayed steaks (PM or LT) and pork chops
erately discolored, undoubtedly as a result of 02 ingress
(LD) were evaluated for color, extent of discoloration, and
through the pack. Steaks in all treatments with 02 scaven-
retail appearance 30-45 min after master pack opening by a
ers inside the retail tray were perceived to be at least
4-5 member trained sensory panel. The details of the eight- g
slightly desirable, except in treatments H and G1 , due to
point descriptive scale for the color of beef, the six-point
extensive discoloration as a result of apparent 02 ingress.
descriptive scale for the color of pork, the seven-point
descriptive scale for discoloration of both beef and pork, and (Table 2c
and FIG. 2A)
the seven-point heclonic scale for retail appearance for both [0148]
Comparison of retail appearance scores for beef
beef and pork are given in Table 2c. Reflectance spectra steaks stored with
and without 02 scavengers indicates the
from the meat surfaces were obtained to estimate the pro- necessity of
including 02 scavengers in master packaged,
portions of metmyoglobin, deoxymyoglobin, and oxymyo- display ready meat
cuts, stored in controlled atmospheres.
globin. Comparison of treatments D and F with
DI and Fl for beef
clearly demonstrates the 02 scavengers should be positioned
[0140] 4. Estimation of the Oxidative Status of Myoglobin inside the
retail tray. (Table 2c)
[0141] Each retail tray containing a steak or a chop was [0149] c. Chemical
States of Myoglobin
evaluated by reflectance spectrophotometry (Macbeth Color
eye 1500/Plus, Kollmorgen Corp., Newburg. N.Y., USA), at [0150] Pork chops
in all treatments previously stored with
three anatomical locations on each cut. Proportions of the 02 scavengers
had 62.0% or more oxymyoglobin and essen-
different chemical states of myoglobin (deoxy-, met-, and tially 0.0%
metmyoglobin when displayed in air, except in
oxy-) were estimated using standard procedures, by con- treatments G and
HI. Chops in treatment G had 2.1% and
verting the readings (R) to K/S values [K is the absorption chops in
treatment H1 had 6.8% metmyoglobin. (Table 2d)
coefficient and S is the scattering coefficient, determined at Beef steaks
in treatments containing 02 scavengers had
selected wavelengths using the formula: K/S.(1¨R)2/2R]. >90.0%
oxymyoglobin, and <2.5% metmyoglobin, except in
Ratios of wavelengths used for calculations are: K/S treatment H and GI .
Steaks in treatment H had 78.5%
4744-K/S 525 for % deoxymyoglobin, K/S 572+K/S 525 for oxymyoglobin and
7.8% metmyoglobin; and steaks in treat-
% metmyoglobin, and K/S 610+.K/S 525 for A oxymyo- meat GI had 58.9%
oxymyoglobin and 37.3% metmyoglo-
globin. bin, presumably as a result of 02
ingress into the package.
(Table 2d) This data confirm the visual data and the require-
[0142] 5. Statistical Analysis ment for 02 scavengers inside the
retail tray when master
packing display-ready meat cuts in controlled atmospheres.
[0143] The influences of different treatments on factors
influencing meat color were compared statistically for sig-
nificant differences (p<0.05) using Analysis of Variance Experiment 2
(Proc ANOVA and LSD means) in SAS (SAS Institute Inc., [0151] a. Oxygen
Concentration
Car)', N.C., USA).
[0152] The initial 02 concentration in every fifth bag was
Results about 120 ppm.
[0153] After one week of storage, the 02 concentration in
Experiment 1 all bags was 0 ppm, except for one bag
(Bag 2, treatment H)
[0144] a. Oxygen Concentration which contained 2650 ppm 02 and was a
"leaker" and was
consequently eliminated from further evaluation.
[0145] The 02 concentration in every fifth bag at initial
packaging was 150-200 ppm. After being stored for one [0154] b. Visual and
Reflectance Properties
week at 2 C. the 02 concentration in most bags with 02 [0155] Although
significant (p<0.05) differences existed
scavengers was 0 ppm, except for bags with treatments H, G, between
treatments in visual color ratings, all steaks were
and GI with beef (Table 2b). Bags without 02 scavengers perceived to be
bright cherry red and no differences of
contained small amounts of 02, occasionally up to 1150 practical importance
existed. Retail trays containing grids
ppm. resulted in steaks with greater amounts
of surface discol-
CA 3043728 2019-05-17
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oration. However, no differences in surface discoloration study. The
appropriate absorbing capacity 01 02 scavengers
attributable to lidding or over-wrapping were detected. to be used appears
to be >600 mL based upon present results.
(Table 2c) Consequently, steaks in retail trays containing [0163] Steaks
and chops used in the present study were
grids were rated less desirable in retail appearance (p<0.05).
vacuum-packaged and stored for two to three weeks at 2 C.
lowever, the magnitudes of these differences in retail
before master packaging, which lowers their metmyoglobin-
appearance were approximately 0.8 of a panel unit making
reducing capacity, and therefore presented a worst-case
them of only marginal practical importance. (FIG. 2B)
scenario for centralized packaging operations.
[0156] Steaks in over-wrapped trays containing a grid had
[0164] Therefore, greater storage ability should be
the highest proportions of oxymyoglobin and the lowest
expected with fresh, un-stored beef or pork. Although pork
proportions of metmyoglobin (p<0.05). Despite this finding,
can probably be master packaged using any treatment-
the visual data clearly indicates inclusion of a grid in the tray
combination with 02 scavengers, the presence of 02 scav-
is not so productive, and the overall data clearly demon-
engers inside the retail tray appears to be imperative when
strates similar advantages for either lidding or over-wrap-
master packaging beef. Treatments G, G2, H, and H2 were
ping the trays. Consequently, the most feasible retail pack-
selected as retail packaging systems, which may be corn-
aging system for use with controlled atmosphere, master
mercially adaptable. Additional replicates of each of these
packaging is the over-wrapped tray containing 0, scavengers
treatments were evaluated in part II of the present study to
underneath an absorbent pad. (Table 2c)
determine the importance of a grid inside the retail tray and
to obtain a comparison of lidded and over-wrapped retail
Experiment 3
trays. Results indicated a grid was not required and there
[0157] a. Oxygen Concentration was little difference between lidded
and over-wrapped trays.
(Table 2c) With CAP master-packages, selection of an
[0158] The 02 concentration at packaging was approxi- appropriate retail
packaging system should include an
mately 80 ppm. After 7 days of storage at ¨1.5 C., the 02 assessment of
the number of 02 scavengers required in each
concentration in all bags was 0 ppm. retail tray to minimize residual 02
concentrations.
[0159] b. Visual and Reflectance Properties [0165] High 02 -permeable film
over-wrap has been shown
[0160] Steaks in retail trays containing 02 scavengers with to act as an 02
barrier at low 0, concentration. Conse-
absorbing capacity of <600 mL were more discolored than quently, two
isolated systems affect the 02 concentration in
the un-stored controls at all display intervals, but discolored the overall
package-atmosphere of master packs. The prob-
essentially the same rate as the un-stored controls. (FIG. ability of
having 02 entrapped inside the retail tray is high
2C) Steaks in retail trays containing 02 scavengers with 800 due to the
absorbent pad and space between over-wrap and
mf, of absorbing capacity also discolored at essentially the edges of the
tray.
same rate as the un-stored controls, but did not discolor as
[0166] The amount of 02 absorbing capacity in each retail
extensively. Tin-stored controls deteriorated rapidly in retail
tray will also dictate the retail display life of meat cuts.
appearance and had a retail case-life of 2.5 days. (FIG. 2D)
Steaks packaged with higher absorbing capacity, i.e., with a
Steaks stored with less than or equal to six 02 scavengers
high absorbing capacity 02 scavengers tend to have more
resulting in 02 absorbing capacity of less than 600 mL also
retail display life than those packaged with low absorbing
deteriorated rapidly in retail appearance and had shorter
capacity 02 scavengers. As the present study demonstrated,
retail-case lives than un-stored controls. Steaks stored with
longer retail display life for steaks packaged with 02 scav-
02 scavengers having absorbing capacity of >600 mL dete-
engers of absorbing capacity >600 mL are achieved relative
riorated more slowly in retail appearance and had retail-case
to 02 scavengers of low capacity. The higher the absorbing
lives in excess of 4 days. (FIG. 2D) The rate of metmyo-
capacity, the shorter the 02 half-life is in the pack atmo-
globin and oxymyogloin (% oxymyoglobin-100-% met-
sphere, resulting in faster removal of residual 02, which in
myoglobin) fotmation during retail display (FIG. 2E)
turn prevents transient discoloration. With prevention of
clearly demonstrates the advantage of using 02 scavengers
transient discoloration, the limited metmyoglobin reducing
and indicates a minimum requirement for 02 scavengers
capacity of the muscle is preserved. This activity further
with absorbing resulting in an 02 half-life of 0.6-0.7 hours
delays development of discoloration during retail display
in the pack atmosphere, where the 02 concentration could
and yields acceptable retail appearance even after four days
otherwise remain less than or equal to 500 ppm at any time
of retail display, as shown in the present study. (Table 2c)
during storage (a deficiency noted in prior art methods).
[0161] C. Discussion [0167] The present study further
demonstrated little
importance for placing meat cuts on a grid and little advan-
[0162] At low temperatures pork color is stable at several tage for lidding
retail-trays. However. 02 scavengers based
hundred ppm of 02. The present study confirmed this upon iron chemical
system with oxygen absorbing capacity
finding. (Table 2c) Beef, especially PM, discolors even at ?:-. 600 ml,
must be placed inside the retail trays to attain an
very low 02 concentrations, which is also evident from the 02 concentration
of 0 ppm in the pack atmosphere of a
results of the present study. The present results clearly master pack of
the size 595x447 mm. The number of 02
demonstrate 02 scavengers arc essential to prevent and/or scavengers can
vary provided they can provide an 02
reduce discoloration in master-packaged meats. The use of half-life of 0.3-
0.4 hours in the master pack. Another corn-
02 scavengers in master packing of pork should provide bination, depending
upon the color stability of meat cuts,
protection to complement the intrinsic ability of pork muscle can be
placing some oxygen scavengers in the master pack
tissue to resist oxidative discoloration and may provide (outside the
retail tray) and only a few in the retail tray.
increased display life. The use of 02 scavengers reduced 02 However, the
commercial system that can deliver a total
concentrations to 0 ppm in most treatments in the present storage and shelf-
life of retail-ready eat cuts should have
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clear plastic tray with oxygen scavengers underneath the sions 152x114 mm
in a 216x133x25 mm solid polystyrene
absorbent pad, and the meat cuts placed on top of the tray. 02 scavengers
with 02 absorbing capacity of at least 10
absorbent pad. (Table 2c and FIG. 2D) cc per pound of meat product were
placed underneath the
absorbent pad. Each retail tray was over-wrapped with a
EXAMPLE 3 shrinkible film having an 02
transmission rate of 8000
mL/(m 24 hour) at 23 C. and 70% relative humidity.
Prevention of Transient Discoloration of [0175] After sealing, the film was
shrunk to the tray using
Retail-Ready Beef Cuts a hot-air gun. Two 3-mm holes were made in the
film at the
corners of the tray to allow free exchange of atmospheres
[0168] Centrally-prepared retail beef cuts stored in con-
during gas flushing. Four such retail trays were placed in a
trolled atmospheres containing nearly 100% carbon dioxide
595x447 mm bimetalized, plastic laminate pouch. The mas-
(CO2) or nitrogen (N,), which may have small amounts of
ter packs were evacuated, filled with 4.5 L N2, and sealed
02, are susceptible to the formation of metmyoglobin due to
the presence of the residual 02. If the 02 concentration is not using a CAP
machine. Eight such master packs were pre-
excessive, the meat will absorb the residual 02 and any pared. Similarly,
eight master packs, each having four retail
t
metmyoglobin formed will be reduced to deoxymyoglobin rays containing two
of another type of 02 scavengers
underneath the absorbent pads; and an additional eight
as a result of metmyoglobin reducing activity (MRA) within
the muscle tissue. In packaged fresh beef 2-4 days are master packs, each
containing four retail trays with no 02
scavengers (controls), were prepared. Each pack was labeled
required for reduction of metmyoglobin to deoxymyoglobin.
When stored meat is removed from the controlled atmo-
accordingly.
sphere, it blooms to the desirable, bright, red color associ- [0176] The
master-packaged steaks were stored at 1 0.5
ated with freshly cut meat, but this will not occur if a C. On day 0, four
retail trays served as fresh controls and
substantial amount of metmyoglobin is present. The MRA of were kept for
visual evaluation in the retail-display case and
muscle tissue is limited and once exhausted cannot convert to obtain
reflectance spectra of the steak surfaces. Three
any metmyoglobin formed back to myoglobin. This results master packs (one
having one type and another one having
in inevitable transient discoloration problem. another type of 02
scavengers, and one having no 02
[0169] Transient discoloration of meat is not a major scavenger), were
opened at 1 day intervals for 8 days and
placed in a retail display case. The 02 concentration in each
concern when the product is in storage. transit. or both for
long periods. However, such discoloration is highly unde-
pack was measured immediately before being opened.
sirable when commercial conditions require periodic rapid [0177] 3. Display
and Sampling of Retail Trays
distribution and display of centrally packaged meat. Conse-
quently, premature temporary discoloration limits the advan- [0178] All
retail trays were placed in the center of the
tages of centrally packaged retail ready meat cuts using display shelf of a
horizontal, fan-assisted retail display case.
02-depleted master packaging technology. Such discolora- The PM steaks on
display were examined for color, disco].
tion is also dependent upon the specific muscle packaged oration, and
retail appearance at 30-45 min after opening of
since tissues vary in their capacity to withstand "low" 02 the master-
packs, and reflectance spectra of the steak sur-
concentrations (<500 ppm). Centrally prepared beefsteaks faces were
obtained to estimate metmyoglobin, deoxymyo-
and ground beef packaged under controlled atmospheres globin, and
oxyuayoglobin content.
were shown to be susceptible to very low 02 concentrations.
[0179] 4. Visual Assessment of Master-Packaged Steaks
Beef muscles with high color stability (LD) are least sus-
ceptible to metmyoglobin formation if atmospheres con- [0180] A five-member
trained panel was used for the
tamed <600 ppm of 02 at temperatures <0 C. however, subjective evaluation
of the steaks. Surface discoloration
beef with poor color stability (PM) was highly susceptible to was evaluated
using a seven-point descriptive scale: 1-.0%
metmyoglobin formation even at very low 02 concentrations (none), 2=1-10%,
3-'11-25%, 4=26-50%, 5-51-75%, 6=76-
and sub-zero temperatures. 99%, 7-100%. Retail appearance was assessed
using a
seven-point bedonic scale: I -extremely undesirable, 2.un-
[0170] The objective of this study was to determine
desirable, 3-slightly undesirable, 4-neither desirable nor
whether 02 absorbent technology might be used in conjunc-
undesirable, 5-slightly desirable, 6-desirable, 7-extremely
tion with CAP to prevent inevitable transient discoloration
of PM beef. desirable.
Materials and Methods [0181] 5. Estimation of Myoglobin
States
[0171] 1. Oxygen Scavengers [0182] The average reflectance spectrum
was obtained
from three locations of the steak covered with a shrinkable
[0172] 02 scavengers, based on iron chemical systems, film using a
reflectance spectrophotometer. Reflectance val-
and having 02 absorbing capacity of at least 10 cc per pound ues (R) of the
different myoglobin oxidation states were
of meat product were used in the study, estimated at specified wavelengths,
and converted to K/S
[0173] 2. Master Packaging, Storage, and Sampling of values (K is the
absorption coefficient and S is the scattering
Steaks coefficient). The K/S values are used
for quantifying the
proportion of deoxy-met-, and oxy-myoglobin, and are
[0174] Twenty fresh beef tenderloins (psoas major, PM) calculated using
selected wavelengths (474, 525, 575, and
from animals slaughtered within 24 hours were obtained 610 nin) for fresh
meat color. The ratios and wavelengths
from a local beef 'packing plant. Four 2 cm thick steaks were used for the
calculations were: K/S 474+ K/S 525 for percent
prepared from each tenderloin and were randomly distrib- deoxymyoglobin,
K/S 575+K/S 525 for percent metmyo-
uted. Each steak was placed on an absorbent pad of dimen- globin, and K/S
610+K/S 525 for percent oxymyoglobin.
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[0183] 5. Statistical Analysis scavengers after 3 and 7 days of
storage (p<0.05). Differ-
ences were most noticeable at 2, 3, 6, and 7 days of storage,
[0184] The effects of treatment differences (control and
where the metmyoglobin content of steaks packaged with
both types of 02 scavengers) were examined statistically
type-II 02 scavengers was reduced to zero. (FIG. 3C)
using analysis of variance (proc ANOVA, SAS Institute,
Inc., Cary, N.C.) at a level of 0.05. Only the main effects Discussion
were analyzed.
[0192] Reduced 02 concentration has been demonstrated
Results to have an adverse effect on meat
color, and PM has been
[0185] a. Visual Assessment of Steaks shown to have the least color
stability, discoloring rapidly
even at very low 02 concentrations (<100 ppm) irrespective
[0186] Discoloration: On day 0, all steaks received dis- of the storage
temperature. Consequently, 02 absorbent
coloration scores of 1 (00/u: discoloration). After subsequent technology
might be used in conjunction with CAP to
daily storage intervals, steaks packaged with no 02 scaven- prevent
inevitable transient discoloration, and this consti-
gers had discoloration scores of either 2 (1-10% discolora- tuted the
hypothesis of the present study. On day 0, the 02
tion), 3 (11-25% discoloration) or 4 (26-50% discoloration) concentration
was 78 ppm and this rose to 477 ppm in
(Table 2c). Steaks packaged with type-one 02 scavengers master packs
without 02 scavengers after 1 day of storage.
received a discoloration score of 1 (0% discoloration) after
2, 4, 7. and 8 days, and 2 (1-10% discoloration) after 1, 3, [0193] Master
packs containing 02 scavengers had no
5, and 6 days. Steaks packaged with type-two 02 scavengers measurable 02 at
most storage times, except after 1 and 2
received discoloration scores of 1 (0% discoloration) at days in the case
of type-I 02 scavengers. As a consequence,
storage intervals of 1, 2, 4, 6 and 8 days, and discoloration steaks with
02 scavengers had low metmyoglobin content
scores of 2 (1-10% discoloration) at storage intervals of 3, and almost no
discoloration, which resulted in significantly
5, and 7 days (FIG. 3A). higher RA scores. Steaks packaged
without 02 scavengers
had an increase in metmyoglobin content from day 0 to day
[0187] Retail Appearance (RA): On day 0, control steaks 3 of storage. After
4 days storage, metmyoglobin content
received retail appearance scores of 7 (extremely desirable), decreased,
but then gradually increased until after 7 days
After subsequent daily storage intervals, steaks packaged storage, when it
decreased again. This indicated these steaks
with no 02 scavengers received RA scores of 5 (slightly underwent two
cycles of transient discoloration, regaining
desirable) or 6 (desirable) after 1, 2, 5, and 7 days. However, color due
to MRA or other reducing factors.
these scores were down to 3 (slight undesirable) or 4 (neither
desirable nor undesirable) after 3, 4, 6, and 8 days of storage. [0194]
Steaks packaged with 02 scavengers did not
Steaks packaged with type-one 02 scavengers received RA undergo such
transient discoloration. Moreover, steaks
scores of 6 (desirable) or 7 (extremely desirable) for all packaged with
type-II 02 scavengers had lower metmyo-
storage intervals, and steaks packaged with type-II 02 globin content than
the fresh control after all storage inter-
scavengers received RA scores of 6 or 7 for all storage vals, and
metmyoglobin content was reduced to zero in some
intervals, except after 7 days when they received RA scores cases. In the
present study. PM steaks expected to have poor
of 5 (slightly desirable) (FIG. 3B). color stability were used, but, very
low metmyoglobin
contents and high RA scores were observed in samples
[0188] b. Metmyoglobin on the Steak Surface packaged with 02 scavengers.
Thus, the hypothesis of com-
[0189] Metmyoglobin content was not significantly differ- bining 02
absorbent technology with CAP to prevent tran-
ent for control steaks (with no 02 scavengers) after most sient
discoloration was proven. (FIGS. 3B and 3C)
storage intervals when compared to fresh controls (p0.05),
[0195] The 0, concentration during initial packaging was
except after 3 and 7 days. Metmyoglobin content increased
78 ppm, and it went up to 477 ppm after 1 day of storage.
from 3.5% on day 0 to 22.8% on day 3, then decreased to
Therefore the amount of time required to reduce the 0,
4.7% on day 4, and again increased to 16.1% on day 7 but
concentration from 477 ppm to 0 ppm would be almost four
decreased to 5.2% on day 8. (FIG. 3C) Discoloration was
times the half-life of 0, in the package atmosphere. For
visible at the edges of these steaks for all storage intervals, ti
type-I and type-II 02 scavengers, incorporating the number
However, these areas were not exposed during reflectance
of scavengers used in the study, the 02 half-life is 0.31 and
spectrophotometry, and thus, the reflectance spectra did not
0.65 hours, respectively (Example 1). Steaks will also con-
report this discoloration, which would have undoubtedly
increased the proportion of inetmyoglobin. (FIG. 3C) tribute to the total
02 absorbing capacity to some extent
(<10%). Thus, at 1 0.5 C., transient discoloration of PM
[0190] Metmyoglobin content of steaks packaged with steaks can be prevented
if residual 02 is reduced to 0 ppm
type-I 02 scavengers was not significantly different when within 3 hours of
pack closure.
compared to control steaks (steaks packaged with no 02
[0196] Selection of ,a suitable retail-packaging system is
scavengers), for all storage intervals (p>0.05), except after 3
and 7 days of storage. Also, the metmyoglobin content was another critical
aspect of master packaging technology using
comparable with that of the fresh control for all storage CAP. It is
evident from the results of the present study that
intervals (p>0.05). (FIG. 3C). the 02 concentration in the master pack
may initially
increase drastically after packaging. Such an increase may
[0191] The metmyoglobin content of steaks packaged be attributed to 02
entrapment either in the absorbent pad or
with type-ll 02 scavengers was not different when compared under the over-
wrap film during evacuation. In addition,
with fresh controls and steaks packaged with type-II 02 meat tissue itself
initially releases dissolved, unreacted 02
scavengers, for all storage intervals (1>0.05). However, causing reduction
of oxymyoglobin to deoxymyoglobin in
steaks packaged with no 02 scavengers had higher metmyo- the presence of
low partial pressures of 02 in the head space
globin content than the steaks packaged with type-II 02 during CAP storage.
This increase is inevitable. Therefore,
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02 entrapment must be minimized to prevent 02 concentra- storage and retail
display life of master packaged beef steaks
tions increasing in the pack to the point where transient (PM) stored under
100% nitrogen atmosphere along with 02
discoloration may occur. absorbents at -1.5 C.
[0197] It has been found that over-wrap film with high 02 Materials and
Methods
permeability acts as an 02 barrier at low initial 02 concen-
trations (Example 1), and the barrier property increases at [0201] 1.
Oxygen Scavengers
low storage temperatures. It is also evident that 02 concen- [0202] 02
scavengers, based on iron chemical system,
tration may increase due to entrapment of 02 in either the were used in the
study. The 02 absorbing capacity was at
absorbent pad or the over-wrap. It is recommended that each least 10 mL per
pound of meat.
retail tray within the master pack contain 02 scavengers to
absorb any 02 entrapped inside tray, which may affect meat [0203] 2. Master
Packaging, Storage, and Sampling of
Steaks
color. Less discoloration occurs on steak surfaces in a
system where 02 scavengers are placed in the master pack. [0204] Fresh beef
tenderloins (psoas major, PM) from
Placing 02 scavengers directly inside the retail tray will also animals
slaughtered 24 hours previously were obtained from
reduce the number of 02 scavengers required, a local beef abattoir. Eighty
steaks of 2 cm thickness were
prepared from these tenderloins. Each steak was placed on
[0198] The present work was designed to examine meat
a 152x114 mm absorbent pad in a 216x133x25 mm (LxWx
samples with the highest pigment instability stored under
H) solid polystyrene tray with 02 scavengers having 02
conditions conducive to discoloration during centralized
absorbing capacity of at least 10 mL per pound placed
distribution. Beef (PM) was placed in over-wrapped retail
underneath the absorbent pad. Each retail tray was over-
trays (which may have 02 entrapped in the absorbent pad or
wrapped with a shrinkable 02 permeable film with an 02
over-wrap or both). Although a storage temperature of
1 0.5 C. is not recommended to optimize storage life of transmission rate
of 8000 mUm2 per 24 hours at 23 C., 70%
relative humidity, and atmospheric pressure. After sealing,
fresh meat cuts in centralized systems, it is closer to the
the film was shrunk to the tray using a hot-air gun. Then, two
optimum (-1.5 C.) than the commercial norm. Rates of
3-mm holes were made at the opposite corners of the tray to
myoglobin oxidation and metmyoglobin reducing activity
allow for exchange of atmospheres during gas flushing. Four
increase and decrease, respectively, at temperatures above 0'
such retail trays were placed in an EVA co-extruded master
C. Thus, better results can be expected at -1.5 C. Never-
pack with 0, transmission-rate of 0.55 mUm2 per 24 hours
theless, under worst-case conditions, the use of 02 scaven-
at 23 C., 70% relative humidity. and atmospheric pressure.
gers in conjunction with CAP prevented transient discolora-
lie bags were evacuated, filled with 4.5 L of N2, and sealed
tion of PM beefsteaks. It is probable that the system used in
using a CAP machine. Twenty such bags were prepared.
the present study will easily prevent transient discoloration
in beef steaks with higher color stability, such as LD, Additionally, 8
retail trays were prepared and treated as
especially if stored below 0 C. Oxygen scavengers should un-stored
controls.
prevent transient discoloration of all centrally prepared beef [0205] The
master packs were stored at -1.5 0.5 C. On
cuts, but, factors such as selection of packaging systems, 02 week 0 and
day 0 of retail display, four steaks in retail trays.
scavenger type, and package atmospheres (N2/CO2) may serving as fresh, un-
stored controls, were analyzed for
affect results. visual, odor, taste, and microbial
characteristics. Also,
reflectance spectra were obtained from the surface of these
EXAMPLE 4 steaks. The visual analysis was done
daily for 4 days. and
similarly reflectance spectra were obtained daily. On day 4
Total Shelf Life of Retail-Ready Meat Cuts Using of retail display, odor,
taste, and microbial analyses were
the Designed Packaging System and Optimized done in addition to visual
examination and reflectance
Oxygen Absorption Technology spectra measurements. Two master packs
were opened at
subsequent 1 week storage intervals for 10 weeks. The 02
[0199] Exploration of an appropriate master-packaging concentration in each
bag was measured immediately before
system, which will minimize both color instability and opening the bag.
microbial spoilage. is imperative for centralized meat opera-
tions. Although research has been done on microbiological [0206] Master-
bags containing meat cuts and oxygen
and sensory aspects of meat during centralized meat pack- scavengers having
oxygen absorbing capacity of at least 10
aging under various modified atmospheres, meat discolora- mL per pound of
meats, placed only outside the meat-trays,
tion due to residual 02 in controlled atmospheres remained were also
prepared. The over-wrap film of the meat-trays
a challenge as the rate of metmyoglobin formation increases had at least
one hole of less than 5 mm diameter. Such
at low partial pressures of 02. master-bags were flushed-back with a
gas-mixture contain-
ing 64.6% Nitrogen. 0.4% CO, and 35% CO,.
[0200] Beef steaks made from muscles of poor color
stability, such as psoas major (PM), discolor rapidly even at [0207] 3.
Display and Sampling of Retail Trays
02 concentrations of <100 ppm and sub-zero temperatures, [0208] Upon
removal from primary CAP storage at
resulting in short storage life in CAP followed by short weekly intervals,
and on day 0 of retail display, master
display life. Consequently, application of oxygen absorption packaging was
removed and each group of 8 retail trays was
technology in conjunction with CAP became an attractive
option. In addition, a suitable retail packaging system is placed in the
center of the display shelf:
required to reduce residual 02 in the controlled atmospheres [0209] The
displayed PM steaks were examined for color.
due to the possibility of 02 entrapment within retail trays. discoloration,
retail-acceptability, off odor intensity, odor
The objective of the present study was to examine the acceptability, and
odor description, 45 min after opening of
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the master-packages. Also, reflectance spectra from the steak Results
surfaces were obtained to estimate metmyoglobin, deoxy-
[0219] a. Measurement of 02 Concentration
myog,lobin, and oxymyoglobin. After visual scores and
reflectance spectra were obtained, two steaks (one from each [0220] The 02
concentration was <100 ppm at initial
master bag) were removed from the display case, and packaging, and after
any CAP storage interval it was reduced
samples were taken for microbial analysis. Then the steaks to 0 ppm, except
after 8 weeks storage when 24 ppm of 02
were cooked and analyzed for flavor acceptability and was measured in one
bag.
off-flavor intensity. [0221] b. Evaluation of Steaks
[0210] The remaining six steaks were left in the display [0222] Although
significant (p<0.05) differences existed
case, and were examined for visual characteristics at sub- between CAP
storage intervals in visual color rating on day
sequent intervals of 24 hours and reflectance spectra at 12 0 of retail
display, that is, when steaks were removed from
hours for 96 hours. Aftcr 96 hours of retail display, the steaks storage,
all steaks were perceived to be bright cherry red or
were analyzed in a similar fashion as on day 0 of retail slightly dark red
and no differences of practical importance
display. During sensory evaluation, the samples remained in existed.
Generally, steaks remained stable in color until they
the display case and the well-trained panelists made judg- became extremely
dark (FIG. 4A) or completely discolored
ments independently. A similar procedure was repeated for (data not shown)
on the fourth day of retail display for any
all storage intervals, storage interval. Due to a leak in the
master pack, steaks
were completely discolored on day 1 of retail display after
[0211] 4. Visual Assessment of Master-Packaged Steaks
1 week of storage. These steaks were removed from retail
[0212] A five-member panel was used for the subjective display and not
analyzed further.
evaluation of the steaks. Color scores were assessed using an
[0223] On day 0 of retail display for any CAP storage
eight-point descriptive scale: 0-Completely discolored, interval, no
significant (p>0.05) surface discoloration was
1-White, 2-Pale pink, 3-Pink, 4-Pale red, 5=Bright cherry
reported on the steaks. The retail display period significantly
red. 6-Slightly dark red, 7-Moderately dark red, 8-Ex-
(p<0.05) increased the amount of surface discoloration on
tremely dark red. Surface discoloration was evaluated using
the steaks for any CAP storage interval. However, the steaks
a seven-point descriptive scale: 14% (none), 2=1-10%,
discolor
3-11-25%, 4=26-50%, 5=51-75%, 6=76-99%, 7-100%. discolored at a faster rate
than the un-stored controls for all
storage intervals, and were relatively extensively discolored
Retail appearance was assessed on a seven-point hedonic
(p4).05). (FIG. 4B)
scale: 1-Extremely undesirable, 2-Undesirable, 3-Slightly
undesirable, 4-Neither desirable nor undesirable, 5-Slightly [0224] Steaks
were extremely desirable in retail appear-
desirable, 6-Desirable, 7-Extremely desirable. ance on day 0 of retail
display for any storage interval
(p>0.05). Despite the fact that they deteriorated more rapidly
[0213] 5. Odor Assessments of Master-Packaged Steaks in retail appearance
than the un-stored controls, they were
[0214] A five-member panel was used for the odor assess- still in the
acceptable range (about 3.5) on the third day of
ment. Off odor intensity scores were assessed using a retail display. (FIG.
4C)
four-point descriptive scale: 1-No off odor, 2-Slight off [0225] From a
practical perspective, steaks were perceived
odor, 3-Moderate off odor, 4-Prevalent off odor; odor to have no off-odors
on day 0 of retail display for any storage
acceptability scores were assessed using a five-point scale: interval,
however, significant differences existed between
1-Acceptable, 2-Slightly acceptable, 3-Neither acceptable storage intervals
with respect to off odor intensity ratings
nor unacceptable, 4-Slightly unacceptable, 5-Unaccept- (p<0.05). The
maximum difference in ratings was 0.3 of a
able; and off odor description scores were assessed using a panel unit,
which is of marginal practical importance. Even
six-point scale: 1-Sour-sulfur rotten eggs), 2-Sour-lactic on day 4 of
retail display, only slight off odors were reported.
acid, 3-Putrid, 4-Dirty socks, 5-Floral/Fruity, 6-Other. (FIG. 4D)
Generally, odor of steaks was acceptable on day
[0215] 6. Microbial Analysis 0 of retail display. (FIG. 4e) Maximum
differences of 0.3 of
a panel unit were noticed after 7 and 8 weeks of CAP
[0216] A 10 cm2 sample was obtained at each sampling storage, which has
little practical significance. Despite sig-
time (on day 0 and 4 of each storage interval) from each of nificant
(p<0.05) differences between storage intervals on
the two steaks using a sterile cork borer. Then, the sample odor
acceptability ratings of day 4 of retail display, all steaks
was placed into a stomacher bag with 10 mL of 0.1 % were perceived to be
slightly acceptable. (FIG. 4E)
peptone solution and was massaged fur 120 seconds using a [0226] Despite
differences (p4).05) between CAP storage
commercial stomacher, yielding a dilution of 100. The =
intervals on microbial numbers at day 0 of retail display,
homogenate was further diluted 10-, 100-, 10,000-, and steaks had <102
cfu/cm2 of total organisms, and no differ-
100,000-fold, after which 0.1 mL volumes of undiluted ences of practical
importance existed. In most cases, micro-
homogenate and of each dilution were prepared and were bial numbers were
comparable with those of un-stored
spread on duplicate plates of APT. The plates were incubated controls.
(FIG. 4F) On day 4 of retail display, microbial
aerobically for 3 days at 25 C. The micro flora was numbers were <100
cfu/cm2 in all cases. (FIG. 4F) When
determined from plates bearing 20-200 colonies.
opened. meat-cuts in master-bags containing 0.4% CO
[0217] 7. Statistical Analysis bloomed quickly when compared with meat-
cuts in master-
bags containing 100% nitrogen.
[0218] The main effects of storage interval and retail
0227] C. Discussion
display period were examined statistically using analysis of 1 -
variance (proc ANOVA, SAS Institute Inc., Cary, NE.) at an [0228] Centrally
prepared retail beef cuts stored in con-
a level of 0.05. trolled atmospheres containing nearly
100% carbon dioxide
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(CO2) or nitrogen (N2), which may have small amounts of [0233] Due to the
increased solubility of 02 and reduction
residual 02, are susceptible to the formation of metmyoglo- in the partial
pressure of 02 required for maximal metmyo-
bin due to the presence of the residual 02. If the 02 globin formation at
sub-zero temperatures, maximum dis-
concentration is not excessive, the meat tissue will metabo- coloration
occurred several millimeters below the meat
lize some of the residual 02 and any metmyoglobin formed surface. Since
meat is translucent, such discoloration is
will be reduced to deoxymyoglobin as a result of metmyo- normally visible.
The deeper in the tissue metmyoglobin
globin reducing activity (MRA) within the muscle tissue. occurs, the lower
is its visibility, and this resulted in low
[0229] In packaged fresh beef, 2-4 days are required for
levels of discernable discoloration and higher retail appear-
reduction of metmyoglobin to deoxymyoglobin. When ance scores during
retail display. Also, use of optimum 02
absorbing capacity in each retail tray prevented transient
stored meat is removed from the controlled atmosphere, it
discoloration of beefsteaks, which probably retained MRA
blooms to the desirable, bright red color associated with
and delayed discoloration further. Prevention of such tan-
freshly cut meat, but this will not occur if a substantial
sient discoloration has been reported above. The combina-
amount of metmyoglobin is present. The MRA of muscle
tion of these hurdles resulted in reduced discoloration even
tissue is limited in stability and once exhausted is not
available to convert metmyoglobin back to deoxymyoglo-
on day 3 of the retail display period. Since the bright-red
bin,
color of meat was restored, the steaks received acceptable
retail appearance scores on day 3 of retail display for any
[0230] To overcome this disadvantage and address the CAP storage interval,
after which the meat was in an
issue of transient discoloration during CAP storage of fresh unacceptable
range. Thus, visual characteristics seem to be
beef, the present work was undertaken to combine the the limiting factor
for acceptability of steaks.
efficacies of CAP storage of fresh beef and 02 absorbent
technology and demonstrate the shelf life extension of [0234] Steaks
had a slight off-flavor on day 0 of retail
display after 8 weeks CAP storage and onwards. Consider-
retail-ready fresh beef under these conditions. Tenderloins
ing the intrinsic variability in meat cuts, such slight dete-
are known to have very poor color stability and discolor
rioration of flavor and odor may be of no practical impor-
rapidly even at very low 02 concentrations and at a storage
temperature of ¨1.5 0.5 C. The effect of intermuscular tancc.
differences on color stability adds another variable that [0235] The
relative success of the system used in the
complicates continuous prevention of meat discoloration, present study is
noteworthy considering the poor color
Biochemical factors, such as oxygen consumption rate stability of PM
muscle. The system is able to deliver longer
(OCR) and MRA, have been reported to be different for CAP storage with
longer subsequent retail display life if beef
different muscles. Therefore, the system was tested using a muscles with
higher color stability are used. It can be
beef muscle type that had poor color stability and repre- conservatively
concluded that the present system has the
seated a worst-case challenge for centralized meat opera- capability of
providing a 10 week CAP storage life with a
tions. subsequent 3 day retail display life
for centrally prepared
[0231] The performance of 02 absorbent technology was beef tenderloin
steaks. Master-bags filled with 0.4% CO will
also put on test during this study for its ability to prevent certainly
need oxygen scavengers placed outside the meat-
transient discoloration by rapidly reducing the residual 02 trays.
concentration to essentially 0 ppm, and thereby preserving
the limited MRA of muscle. Retained MRA may further EXAMPLE 5
enhance retail display life of steaks. It is also true that steaks
packaged with an optimum 02 absorbing capacity have more Shelf Life
Extension of Lamb Chops Utilizing
retail display life when compared with steaks packaged Zero-Oxygen Tech
without such capacity. Thus, the system used in the present [0236] 1.
Master-Packaging, Storage, and Sampling of
study was believed to have the capability to provide solu- Steaks
tions for the major problems of residual 02 concentrations
encountered in centralized fresh meat distribution. [0237] Fresh lamb
primal cuts from animals slaughtered
24 hours previously, were obtained from a lamb abattoir.
(0232] For all CAP storage intervals, the steaks had
acceptable visual, odor, and flavor scores on day 0 of retail Eighty
chops of 2-cm thickness were prepared from these
cuts. Each chop was placed on an absorbent pad and a foam
display. Additionally, metmyoglobin content and microbial
tray, with 02 scavengers having an absorption capacity of at
growth were minimal and in some cases even lower than in
least 10 cc (e.g. 10 mL) per pound placed underneath the
fresh controls on the day packs were opened and displayed.
Along with a low storage temperature of ¨1.5 0.5 C., an absorbent pad.
Each retail tray was over-wrapped with a
shrinkable 02 permeable film with an 02 transmission rate of
important factor influencing microbial content was low
8000 mL per m2 per 24 hours at 23 C., 70% relative
initial microbial load. Beef tenderloins were used in the
humidity, and atmospheric pressure. After sealing, the film
study, and these muscles are internally located and do not
undergo much handling by meat-cutters as compared to was shrunk to the tray
using a hot-air gun. One 3-mm hole
was made at the opposite corners of the tray. Four such retail
other cuts. This protects them to some extent from cross-
contamination, and hence yields low initial microbial load, trays were
placed in per 24 hours at 23 C., 70% relative a master pack with 02
transmission-rate
The meat cuts used in the present study had very low initial m2of 0.55 mL
per
microbial numbers, which would have delayed onset of humidity, and
atmospheric pressure. Master bags containing
spoilage levels of microorganisms, and thus may have 02 scavengers outside
the meat trays and inside the master
reduced the occurrence of off-odors. It was not surprising bag were also
prepared.
that microbial growth and odor did not limit CAP storage [0238] The bags
were evacuated, filled with 4.5 L of N2
and retail display life of steaks. and sealed using a CAP machine. Ten
such bags were
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prepared. Similarly, ten such packages were prepared by [0246] 5. Flavor
Assessment of Master-Packaged Lamb
using plastic trays instead of foam trays. During initial Chops
packaging, the 02 concentration was measured in every fifth
[0247] The lamb chops were cooked the lamb chops after
bag by using an 02 analyzer (Mocon MS-750, Modern 27 and 55 days of storage
for flavor assessment.
Controls Inc., Minneapolis, Minn.), which uses a solid state
02 ion conduction material, zirconium oxide. The 02 ana- [0248] 6.
Microbial Assessment
lyzer had an accuracy of t5 ppm in the 0 ppm to 1000-ppm
[0249] Analysis of the lamb chops, after every weekly
range, 0.05% in the 0.1% to 10% range, and t0.1% in the storage interval,
for aerobic, anaerobic, E. colt, Listeria, and
10% to 100% ranges for 02 concentrations. The resolution Salmonella was
performed.
of the analyzer was smaller than the accuracy; that is, in the
Results
0 to 1000 ppm 02 concentration range the resolution was 1
ppm. [0250] a. Oxygen Concentration
[0239] The master packs were stored at -1.5 C. Two [0251] The oxygen
concentrations in the master packages
master packs (one containing foam trays and the other were in the range of
0.5% immediately after packaging
containing plastic trays) were opened at subsequent 1 week which went up to
2-5% within a few minutes of gas flushing
storage intervals for 8 weeks. The 02 concentration in each and sealing.
The oxygen concentration was reported to be 0
bag was measured immediately before opening the bag. for each weekly
storage interval.
Master bags containing meat cuts and oxygen scavengers
having oxygen absorbing capacity of at least 10 cc per pound [0252] b.
Visual, Odor, Microbial and Flavor Assessment
of meats, placed only outside the meat-trays, were also [0253] The lamb
chops had bright red to dark red color,
prepared. The over-wrap film of the meat-trays had at least zero to minimal
discoloration, extremely acceptable appear-
one hole of less than 5 mm diameter. Such master-bags were ance, and no off-
odor for all the storage and display time
flushed-back with a gas-mixture containing 64.6% Nitrogen, intervals.
(FIGS. 5C1-5J) The microbial load showed a
0.4% CO, and 35% CO2. gradual increase in the count, with no
detrimental effect to
the meat quality. Also, pathogen-growths were negative for
[0240] 2. Display and Sampling of Retail Trays
all storage intervals. (FIGS. 5A-58) The flavor was assessed
[0241] Upon removal from primary CAP storage at to be extremely acceptable
after 27 days of storage.
weekly intervals, and on day 0 of retail display, master [0254] c.
Discussion
packaging was removed and each group of 8 retail trays was
placed for sensory analysis. The displayed chops were [0255] The lamb chops
were extremely desirable for all
examined for color, discoloration, retail-acceptability, off storage
intervals and display periods. The testing showed no
odor intensity, odor acceptability, and odor description, 20 difference
between chops packaged in plastic and foam trays
min after opening of the master-packages. After visual and with all having
retail acceptability and no odor throughout
odor scores were obtained, two chops (one from each master the display
period. (FIGS. 5C-I-5J) No substantial difference
bag) were removed from the display case, and samples were in desirability
was reported for lamb cuts in the master bags
taken for microbial analysis. A similar procedure was with 02 scavengers in
meat trays or in master bags with 02
repeated for all storage intervals, scavengers placed only outside the meat
trays; i.e. in the
mater bags. It is believed this is due to preventing the
[0242] 3. Visual Assessment of Master-Packaged Lamb metmyog,lobin reducing
activity of the muscle by absorbing
Chops the oxygen rapidly to zero levels. This
enhances the display
life of centrally prepared retail ready meat cuts. In addition,
[0243] A three-four-member panel was used for the sub- a nitrogen
atmosphere provides an anaerobic atmosphere,
jective evaluation of the steaks. Color scores were assessed and helps in
reblooming of the meat once removed from the
using an eight point descriptive scale: 0-Completely discol- master
package. When opened, meat-cuts in master bags
ored, 1-White, 2-Pale pink, 3-Pink, 4-Pale red, 5-Bright containing 0.4% CO
bloomed quickly when compared with
cherry red, 6-Slightly dark red, 7-Moderately dark red, meat-cuts in master-
bags containing 100% nitrogen. Master
8-Extremely dark red. Surface discoloration was evaluated bags filled with
0.4% CO will certainly need oxygen scav-
using a seven point descriptive scale: 1=0% (none), 2=1- engers placed
outside the meat-trays.
10%, 3=11-25%, 4=26-50%, 5=51-75%, 6=76-99%,
7=100%. Retail appearance was assessed on a seven point [0256] The zero
oxygen packaging system for centralized
hedonic scale: 1=Extremely undesirable, 2-Undesirable, meat operations
extends the available display and storage
3-Slightly undesirable, 4-Neither desirable nor undesirable, times for the
meat. A storage life of 8+ weeks with a
5-Slightly desirable, 6-Desirable, 7=Extremely desirable. subsequent
display life of 4+ days was obtained for centrally
prepared retail ready lamb chops by employing zero oxygen
[0244] 4. Odor Assessments of Master-Packaged Lamb storage.
Chops
EXAMPLE 6
[0245] A three to four-member panel was used for the odor
assessment. Off odor intensity scores were assessed using a
Shelf Life Extension of Pork Chops by F,mploying
four point descriptive scale: 1-No off odor, 2-Slight off
odor, 3-Moderate off odor, 4-Prevalent off odor; odor "Zero Oxygen
Packaging System"
acceptability scores were assessed using a five-point scale: [0257] 1.
Master Packaging, Storing, and Sampling of
1-Acceptable, 2-Slightly acceptable, 3-Neither acceptable
Pork Chops
nor unacceptable, 4-Slightly unacceptable, 5-Unaccept-
able; and off odor description scores were assessed using a [0258] Fresh
pork loins from animals slaughtered 24 hours
six-point scale: 1-Sour-sulfur (rotten eggs), 2-Sour-lactic previously,
were obtained from a local beef abattoir. One
acid, 3-Putrid, 4-Dirty socks, 5-Floral/Fruity, 6=Other, hundred and twenty
chops of 2 cm thickness, were prepared
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from these porkloins. Each pork chop was placed on a 3-11-25%, 4-26-50%, 5-
51-75%, 6.76-99%, 7.100%.
152x114 rum absorbent pad in a 216x133x25 mm (LxWxH) Retail appearance was
assessed on a seven-point hedonic
solid polystyrene tray with 02 scavengers of 02 absorption scale: I-
Extremely undesirable, 2-Undesirable, 3-Slightly
capacity of at least 10 mL per pound of meat placed undesirable, 4-Neither
desirable nor undesirable, 5-Slightly
underneath the chop. Master bags where 02 scavengers were desirable, 6-
Desirable, 7-Extremely desirable.
placed only outside the meat trays were also prepared. Each
retail tray was over-wrapped with a shrinkable 02 permeable [0265] 4. Odor
Assessments of Master-Packaged Chops
film with an 02 transmission rate of 800 mL/m2 per 24 hours [0266] A five-
member panel was used for the odor assess-
at 23 C., 70% relative humidity, and atmospheric pressure. meat. Off odor
intensity scores were assessed using a
After sealing, the film was shrunk to the tray using a hot-air four-point
descriptive scale: 1-No off odor, 2-Slight off
gun. Then, two 3-mm holes were made at the opposite odor, 3-Moderate off
odor, 4-Prevalent off odor, odor
corners of the tray to allow free exchange of atmospheres acceptability
scores were assessed using a five-point scale:
during gas flushing. Four such retail trays were placed in an 1-Acceptable,
2-Slightly acceptable, 3-Neither acceptable
EVA co-extruded master pack with 02 transmission-rate of nor unacceptable,
4-Slightly unacceptable, 5-Unaccept-
0.55 mL/m2 per 24 hours at 23 C., 70% relative humidity, able; and off
odor description scores were assessed using a
and atmospheric pressure. The bags were evacuated, filled six-point scale:
1-Sour-sulfur (rotten eggs), 2-Sour-lactic
with 4.5 L of Is12, and sealed using a CAP machine. Thirty acid, 3-Putrid,
4-Dirty socks, 5-Floral/Fruity, 6-other.
such bags were prepared. An additional 8 retail trays were
prepared and treated as un-stored controls. [0267] 5. Microbial Analysis
[0259] The master packs were stored at -1.5 0.5 c On [0268] A 10 cm2
sample was obtained at each sampling
week 0 and day 0 of retail display, four steaks in retail trays, time (on
day 0 and 4 of each storage interval) from each of
serving as fresh, un-stored controls, were analyzed for the two chops using
a sterile cork borer. Then, the sample
visual, odor, taste, and microbial characteristics. The visual was placed
into a stomacher bag with 10 ml. of 0.1%
analysis was done daily for 6 days. On day 6 of retail display, peptone
solution and was massaged for 120 seconds using a
odor, taste, and microbial analyses were done in addition to commercial
stomacher, yielding a dilution of 10 . The
visual examination. Two master packs were opened at homogenate was further
diluted 10-, 100-, 1000-, 10000-,
subsequent 1 week storage intervals for 15 weeks. The 02 and 100,000-fold,
after which 0.1 nil, volumes of undiluted
concentration in each bag was measured immediately before homogenate and of
each dilution were prepared and the
opening the bag. Master bags containing meat cuts and spread on duplicate
plates of APT. The plates were incubated
oxygen scavengers having oxygen absorbing capacity of at aerobically for 3
days at 25 C. The micro flora was
least 10 cc per pound of meats, placed only outside the determined from
plates bearing 20-200 colonies. (FIG. 6F)
meat-trays, were also prepared. The over-wrap film of the Results
meat-trays had at least one hole of less than 5 mm diameter.
Such master-bags were flushed-back with a gas-mixture [0269] a. Measurement
of 02 Concentration
containing 64.6% Nitrogen, 0.4% CO, and 35% CO2.
[0270] The 02 concentration was 5% at initial packaging,
[0260] 2. Display and Sampling of Retail Trays and after a CAP storage
interval it was reduced to 0 ppm.
The oxygen concentration was down to 0 ppm within three
[0261] Upon removal from primary CAP stroage at
hours of master pack closure.
weekly intervals, and on day 0 of retail display, master
packaging was removed and each group of 8 retail trays was [0271] b.
Evaluation of Chops
placed in the center of the display shelf. The displayed pork
chops were examined for color, discoloration, retail-accept- [0272] A
storage life of at least 15 weeks and a retail
ability, off odor intensity, odor acceptability, and odor display life of
at least six days for pork chops packaged by
description, 45 min after opening of the master-packages. employing "zero
oxygen packaging systems approach" were
obtained. (FIGS. 6A-6F) When opened, meat-cuts in mas-
[0262] After visual scores were obtained, two chops (one ter-bags
containing 0.4% CO bloomed quickly when corn-
from each master bag) were removed from the display case, pared with meat-
cuts in master-bags containing 100% nitro-
and samples were taken for microbial analysis. The remain- gen. Master bags
filled with 0.4% CO will certainly need
ing six chops were left in the display case, and were oxygen scavengers
placed outside the meat-trays.
examined for visual characteristics at subsequent intervals of
24 hours and reflectance spectra at 12 hours for 96 hours. [0273] It is
interesting to note that the visual and microbial
After 144 hours of retail display, the chops were analyzed in
characteristics of the pork chops remained in an acceptable
a similar fashion as on day 0 of retail display. During sensory condition
even after such a long storage in cooler and at
evaluation, the samples remained in the display case and the retail display
case.
well-trained panelists made judgments independently. A
similar procedure was repeated for all storage intervals. DEMONSTRATED
PRINCIPLES
[0263] 3. Visual Assessment of Master-Packaged Chops [0274] 1. Metmyoglobin
reducing activity is capable of
being restored provided the oxygen concentration in the
[0264] A five-member panel was used for the subjective master package which
contains meat cuts is reduced to zero
evaluation of the steaks. Color scores were assessed using an ppm within a
few hours of sealing the package.
five-point descriptive scale: 0-Completely discolored,
1-Extremely pale, 2-Pale, 3-Normal, 4-Dark, 5-Ex- [0275] 2. Oxygen
absorption kinetics by an oxygen scav-
tremely dark. Surface discoloration was evaluated using a eager is bi-
phasic where the rate of oxygen absorption varies
seven-point descriptive scale: 1.0% (none), 2-1-10%, with the initial
oxygen concentration.
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[0276] 3. Pre-treating the oxygen scavengers by moisture 02 scavengers must
also self-activate in the presence of 02
causes faster activation, at a >60% relative humidity (caused by
the fresh meat cuts).
[0277] 4. Oxygen scavengers based on an iron chemical [0286] Besides the
half-life of residual 02 concentration in
system can be effectively utilized to reduce the oxygen the bag. an
important consideration is the type of meat cuts.
concentration in the master bag. Beef and lamb/veal muscles, especially
tender loins, have
very poor color-stability, and metmyoglobin formation, with
[0278] 5. The oxygen half-life will be dependent upon the the concurrent
discoloration, has the highest rate for these
initial oxygen concentration in the package and the ambient muscle-types.
Hence, a very fast oxygen scavengers
temperature. (capable of working at 0-4 C.) with an
optimal capacity of
[0279] 6. The permeability of packaging films having very 10-1000 cc (e.g.
10-1000 mL) per pound of meat (depending
high oxygen ingress rate is significantly reduced at sub-zero upon the
location of meat muscle, i.e., loins, ribs, etc.) is
desired in a master bag with residual oxygen concentration
temperatures where the films act as an oxygen barrier.
of less than 5%. Also, placement of the 02 scavengers should
[0280] Included within the scope of the present invention be close to the
meat cuts to avoid any discoloration due to
and the abovementioned examples are compositions corn- oxygen-entrapment.
prising various combinations of these substances and mate-
rials. Aspects of the present invention have been described
color stability. Fast oxygen scavengers (capable of working
by way of example only and it should be appreciated that
at 0-4 C.) with an optimal capacity of 10-500 cc (e.g.
modifications and additions may be made thereto without
departing from the scope thereof. 10-500 mL) per pound of meat cut is
desired in a master-bag
with residual oxygen concentration of less than 5%. For pork
INDUSTRIAL APPLICABILITY products, oxygen scavengers can be
placed outside the
meat-trays within the master bag. For other meats (e.g. beef,
[0281] The present invention finds specific industrial lamb, and veal), the
oxygen scavengers can either be inside
applicability in the meat distribution and retail industries, the meat
trays, or inside the master bag and outside the meat
The automated machine disclosed herein used to package trays, depending on
the muscle type. In either case, oxygen
meat cuts achieves zero oxygen packaging in a central Permeability of the
meat trays must be sufficient for residual
packaging facility for master bag storage and retail display. trapped
oxygen to diffuse out of the meat trays.
The storage and display times are significantly increased [0288] The
primary consideration is to have fast-type
using the system. oxygen scavengers with the capability
to reduce oxygen
[0282] FIG. 7 shows the basic steps employed in the concentrations to 0 ppm
(zero oxygen level) within 24 hours
invention organized in to four separate procedures or pro- of packaging
closure. Optimal oxygen scavenging capacity
cesses. Steps 705-715 comprise the first procedure of deter- is between 10
cc to 1000 cc (e.g. 10 mL to 1000 mL) per
mining the capacity of the 02 scavenger to use. Step 720 pound of meat-cuts
in a master-bag having residual oxygen
comprises the second procedure of determining placement concentration of
less than 5% and resulting in a half-life for
of the 02 scavenger. Steps 725-735 is the third procedure of oxygen ranging
from 0.6 to 2 hours.
packaging, and steps 740-750 are the fourth procedure of [0289] The desired
oxygen scavengers is chemical-based,
storage and display of the meat. because enzyme-based scavengers have
been shown to have
[0283] For determining the half-life process, in step 705, low oxygen
absorption rates as shown in the data presented
in this and the earlier Ser. No. 10/434,010 application. Iron
the master bag is selected and prepared. The master bag must
chemical systems, from the chemical group of ferrous and
exhibit low oxygen transmission-rates, preferably <10
cc/m2/day at 23 C. Typically, this will require a master bag ferric ions,
are the preferred oxygen scavenging materials.
composed of high oxygen barriers films such EVOH or foil, However, other
chemical groups such as magnesium and
and the master bag must have good seal-strength. copper can be used. The
material used is finely granulated to
a powdered form and its capacity is determined by the
[0284] The oxygen permeability of the bag must also be amount of powdered
material placed inside a sachet. The
established. A master bag is filled with the appropriate preferred
composition of the scavenger material follows:
quantity of 100% nitrogen (or any other inert gas) or a
combination of >50% nitrogen (or other inert gas) plus other[0290] iron (<25%,
preferred range 15-20%)
non-inert gases (e.g. CO, and/or CO or other gases) and then [0291] carbon
(<35%, preferred range 20-25%)
the residual 02 level in the bag is measured immediately
[0292] vermiculite (<20%, preferred range 10-15%)
after sealing, three hours after sealing, and 24 hours after
sealing using different sampling sets of bags for each men- [0293]
dcionized water (<10%, preferably 5%)
surement.
[0294] salt (preferably NaCI, <10%, preferably 5%)
[0285] In step 710, residual 02 concentration in the bag is
[0295] The desired capacity of oxygen scavengers used
taken into consideration and an appropriate Arrhenius equa-
tion is used to calculate the half-life of oxygen in the master ranges from
10 cc to 1000 cc per pound of meat packaged
in a master bag. The exact capacity and half-life is calculated
bag, and an appropriate 02 scavenger with an optimum
capacity is designed or selected. In step 715, the 02 scav- based on the
Arrhenius equation found in patent application
Ser. No. 10/434,010. The scavengers need to function in the
eager is chosen. The scavenger chosen must have sufficient
capacity (10 cc-1000 cc) to rapidly absorb the 02 to the temperature range
of ¨2.222 to 7.222 C. (28 to 40 F.).
required low level and achieve a zero oxygen storage [0296] For the next
procedure of determining placement of
atmosphere within 24 hours of sealing the master bag. The the 02 scavenger,
in step 720 placement of the 02 scavenger
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depends primarily on the meat type. Depending on the can be constructed
from any acceptable, standard material
meat-type. the 02 scavenger can be placed inside the meat- commonly used
for meat trays, preferably styrofoam. The
tray or outside the meat-tray in the master bag. For beef and over-wrap 710
likewise can be made from any conventional
lamb cuts, placing the 02 scavenger inside is usually con- oxygen permeable
plastic wrapping film. In this embodi-
sidered optimal. However, 02 scavengers can be placed ment, the meat 715 is
placed on top of and in direct contact
with the oxygen scavenger sachet, with an absorbent pad
outside the meat-trays provided one or more pin-holes are
725 placed underneath the oxygen scavenger. FIG. 9 shows
made in the over-wrapping film surrounding the meat-tray,
another embodiment. The meat tray 805 is covered by the
each hole having a diameter of less than 5 mm. It is
important for the film over-wrapping to allow exchange and plastic over-
wrap 810. However, in this embodiment the
meat 815 is placed on top of and in direct contact with the
diffusion of atmosphere, or more specifically oxygen,
absorbent pad 820. The oxygen scavenger sachet 825 is
between the interior and exterior of the meat tray when
placed underneath the absorbent pad 820. For both of these
sealed in the master bag. embodiments, oxygen scavenger sachets
used attain enough
[0297] For the third procedure of packaging the meat, in absorption
capacity to achieve an 02 half-life of between 0.6
step 725 between 0.5-4.0 lbs of meat are placed on appro. to 2.0 hours. It
is preferred that the oxygen absorption
ptiate trays. Conventional foam trays can be used in the capacity be at
least 10 mL per pound of meat and attain a
packaging. Tests performed using foam and plastic trays, zero oxygen
storage atmosphere within 24 hours of pack-
both over-wrapped and lidded, showed no substantial dif- aging.
ference.
[0302] FIG. 10 shows an embodiment for a master bag
[0298] In step 730, the meat trays are over-wrapped for containing meat
trays with the oxygen scavengers only
eventual display in a meat case. The over-wrapping film found inside the
meat trays sealed in the master bag. The
must have high oxygen transmission rates on the order of master bag 905
will contain one or more meat trays 910. The
>8000 cc/m2/24 hours at 23 C. At least one pin-hole of <5 atmosphere
within the master bag 905 is flushed of oxygen
mm diameter must be made on the over-wrapping film that and injected with a
non-oxygen gas consisting primarily of
wraps the meat-trays to prevent oxygen entrapment inside 100% nitrogen or a
nitrogen-rich (>50% nitrogen) gas
the meat-trays or allow diffusion out of oxygen entrapped mixture before
sealing. FIG. 11 shows an embodiment of a
within the meat-trays (e.g. depending on whether the 02 master bag
containing a cut of primal or sub-primal meat.
scavengers are located inside the tray or the mater bag). The
[0303] 02 scavengers placed inside the master bag, typi-
pin-holes are required because despite the permeability of
cally possess 02 absorbing capacity of 10 cc/lb (e.g. _410
the film, the film still acts as an oxygen-barrier, and oxygen
mL/lb) of meat. In this embodiment, the master bag 1005
molecules become entrapped within the meat-tray causing
contains cuts of unwrapped primal or sub-primal meat 1010.
discoloration to the meat. However, for pork, the pin-holes
The master bag 1005 is flushed of oxygen and injected with
can be eliminated. This diffusion action permits trapped
a non-oxygen gas consisting primarily of 100% nitrogen (or
oxygen to defuse outside the tray and be absorbed by oxygen
any other inert gas) or a combination of >50% nitrogen (or
scavengers outside the tray, or conversely for residual oxy-
other inert gas) plus other non-inert gases (e.g. CO, and/or
gen trapped in a master bag lacking oxygen scavengers to
diffuse into a tray for absorption by scavengers within a meat CO or other
gases) before sealing.
tray. [0304] Oxygen scavenger sachets 1015
with appropriate
[0299] In step 735, single or multiple meat trays are placed capacity are
added to the master bag 1005 before sealing
into a master bag, which will include an 02 scavenger of having a total
oxygen absorbing capacity of -.10 mL per
appropriate 02 absorbing capacity. The master bag is gas- pound of meat to
achieve an 02 half-life of between 0.6 to
flushed (single or multiple flushings either with or without a 2.0 hours.
FIG. 12 shows another embodiment where meat
vacuum to aid removing oxygenated air) using either 100% trays and oxygen
scavengers are sealed in a master bag. The
N2 or >50 N2 and the balance with CO, CO2 and other trace master bag 1105
contains a plurality of meat trays 1110.
amounts of non-oxygen gases (e.g. He, H2, H20, etc) to Oxygen scavenger
sachets 1115 are included inside the
achieve a residual 02 concentration of less than 5% inside master bag 1105
before the master bag 1105 is flushed,
the master bag. The N2 atmospheric content preferably injected with the
desired gas mixture, (100% nitrogen,
ranges between 56%400%. A small percentage of CO nitrogen-rich (>50%
nitrogen) with balance of CO2 and
(<5%) will aid in retaining color of the meat. The preferred CO), and then
sealed.
CO content ranges between 0.1 % to 5%. After the desired [0305] The
invention also includes the apparatus used for
gas mixture is injected into the bag, it is sealed and the packaging the
master bags. The apparatus consists of hori-
oxygen scavengers, both inside and outside the trays, absorb -zontal-form-
fill-seal equipment designed to provide an inte-
any residual oxygen. grated packaging system for retail-
ready meat cuts in meat
[0300] The fourth procedure includes steps required for trays or primal or
sub-primal meat cuts of the appropriate
storage and distribution for display. In step 740, the master size. The
preferred maximum size of product packaged by
bags are placed in storage under temperatures in the range of the machine
is 28 inches long, 18 inches wide, and 6 inches
0 to -2.22 C. (e.g. 32 -28 F.). In step 745, the meat is high. The
equipment should be constructed of stainless steel
distributed to appropriate grocers or grocer distribution to facilitate
cleaning. FIG. 13 shows a basic schematic of the
centers with storage maintained under 40 F. Meat can be Packaging system
using the machine.
maintained in this storage and distribution packaging for up [0306] In the
machine schematic of FIG. 13, meat trays
to 15 weeks depending on the type of meat. In step 750, the 1205 of the
preferred maximum size are fed into the appa-
meat is removed from the master bags and placed in meat ratus using a
conveyor system 1207 powered by a servo
displays at the appropriate grocer under temperature condi-
motor that moves
tions >0 C., typically for up to nine days. the
meat trays 1205 through the apparatus.
For most meat packaging applications, the appropriate oxy-
[0301] FIG. 8 shows the arrangements of the elements of gen scavenger
sachets 1210 will be placed inside the meat
a meat tray for one embodiment for a meat tray. The tray 705 tray and
outside the meat tray inside the master bag, but for
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some chosen applications other placement configurations will
provide all the nitrogen for the system, and this nitrogen
may be used (e.g. scavengers in meat tray only, scavengers gas
flow may be in a gaseous or liquid state, preferably
outside meat tray only, or no scavengers). A pin-hole of g 5
gaseous as cryogenic temperatures of liquid nitrogen can be
mm should be punched in the over-wrap of the meat tray, or
problematic and would needlessly complicate the system
multiple holes to facilitate diffusion of trapped oxygen from
without any real benefit. The other gas line will supply the
the retail meat trays.
mixture of other gases chosen by the user of the system
(CO2, CO, etc).
[0307] The meat trays 1205 enter a folding box 1211
which constructs the master bags. One or more 1205 meat
[0310] Alternatively, each gas type may use its own gas
trays enter the folding box 1211, which is supplied with the
supply line, but it is contemplated that the gas feed for the
master bag material by a film pulley system 1212 supplying other
gases will be in a gaseous state and a safety valve 1223
bag film material 1214 from a continuous sheet of material is
provided on this gas supply line 1224 for venting in the
wrapped onto a roller system 1213. The folding box 1211 even
that the pressure rises to an unsafe level inside the tank
folds the fed master bag film material 1214 around the meat 1220.
The preferable gas mixture for most meat packaging
trays 1205 to form the master bag by heat-sealing the edges will
be composed of >50 N2 and <5% CO and the balance
together to form a master bag. Alternatively, the continuous of
the mixture CO,. A safety system may be required for
sheet roller system 1213 may consist of a number of
monitoring with these gas mixtures containing CO and CO2,
prefabricated master bags coupled together by perforations which
can be dangerous at relative low concentrations (e.g.
so as to be easily separated and opened by the folding box over 50 ppm for
CO gas and over 5,000 ppm for CO2).
1211.
[0311] The sides of the master bag are heat-sealed before
[0308] As the forming master bag passes through the gas
flushing and the ends of the master bag are heat-sealed
folding box, a wrapper pre-heating mechanism 1215 heats by a
cross-reciprocating seal mechanism utilizing a specific
the material to help shrink it onto the meat trays 1205, before dwell
time, speed, pressure, and temperature. A servo motor
reaching a set of propelling and sealing rollers 1216 that seal
controls the cross reciprocating seal. The parameters (speed
the end of the master bag. During this process, between the of
the conveyor and cross-sealing speed) depend on the size
mechanisms of 1215 and 1216, simultaneously with the of
the master bag. All of the functional components such as
formation of the master bag, gas flushing is performed to the
servo motor, conveyor speed, cross-sealing speed, gas
evacuate air out of the master bag while the desired gas
mixture control, bag sizing, and other similar functions, are
mixture is injected. The gas flushing can include applying a
preferably controlled by a Pentium-based computer control
vacuum to the master bag to help evacuate ambient air from
system operated by a windows style touch screen. At the end
the master bag. of
the process, a master bag 1226 containing meat trays or
primal cuts of meat is produced containing a desired gas
[0309] The gas mixture is supplied from a gas supply tank
1220 containing pre-mixed gases supported above the con-
mixture reduced to zero oxygen content for long-term stor-
a of the meat cuts.
veyor system by a support rack 1217, or the gas can be ge
supplied from multiple tanks, or gas lines leading to an
[0312] While the invention has been particularly shown
exterior tank of pre-mixed gases. Gas is supplied through a and
described with respect to preferred embodiments, it will
gas supply line 1218, with gas flow regulated by a solenoid be
readily understood that minor changes in the details of the
valve 1219. The gas tank includes warning devices 1221 that
invention may be made without departing from the spirit of
can include pressure, temperature, and composition sensors, the
invention. Having described the invention,
It is contemplated that two gas supplies lines will flow into
the tank. A nitrogen gas line 1222 will supply pure N, to the EXAMPLE I
gas tank, and may include a bypass to feed directly into the
gas supply line 1218 into the apparatus. The N2 supply line [0313]
TABLE lA
Half-life of 02 in bags containing scavengers based upon enzymes and iron
chemical systems, and air or N, atmosphere.
0, half-life (h)
Scavenger-type Atmosphere 25 C. 12 C. 2
C. -1.5 C.
Iron chemical system Air 0.6 (0.04)* 0.7 (0.02) 1.0
(0.03) 2.5 (0.04)
(type 1) N2 air 1.3 (0.03) 1.5 (0.04)
2.2 (0.05) 2.3 (0.05)
Enzyme system (type 1) Air 1.0 (0.03) 1.6 (0.02)
4.0 (0.02) 7.1 (0.04)
N2 4- air 3.3 (0.02) 7.1 (0.03)
12.0 (0.03) 8.4 (0.03)
Iron chemical system Air 0.6 (0.04) 0.8 ((P.05)
0.8 (0.04)
(type 2) N2 + air 0.9 (0.02) 0.9 (0.04)
1.3 (0.04)
Enzyme system (type 2) Air 1.6 (0.02)
N2 + air 6.5 (0.06)
Iron chemical system Air 4.5 (0.08)
(tY0e 1 in over-wrapped N2 + air 5.0 (0.08)
tray)
Standard deviation.
- An experiment was not performed under this condition.
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[0314]
TABLE IB
Constants of first order kinetics equation for different scavengers.
Constants of
first order Calculated
Temp. Initial 02 kinetics equation 02 half-
Correlation
Scavenger-type (` C.) Atmosphere concentration (ppm) k (11-') Ao
life' (h) coefficient (r2)
Iron chemical system 25 Air 200,000 2.46 3.94 0.3
0.98
(type 1) 25 N, + air 500 0.35 0.51 1.8 0.92
12 Air 200,000 1.82 396 0.4 0.96
12 N2 + air 500 0.36 0.61 1.9 0.98
2 Air 200,000 0.69 3.61 1.0 0.99
2 N2 -e= air 500 0.25 0.79 2.7 0.99
-1.5 Air 200,000 0.31 3.54 2.3 0.92
-1.5 112 + air 500 0.26 0.76 2.7 0.99
Enzyme (type 1) 25 Air 200,000 0.56 3.34 1.2 0.99
25 N2 + air 500 0.20 0.88 3.5 0.99
12 Air 200,000 0.40 3.62 1.7 0.99
12 N2 + air 500 0.09 0.84 7.7 0.99
2 Air 200,000 0.20 3.45 3.5 0.99
2 N2 + air 500 0.06 0.80 11.5 0.96
-1.5 Air 200,000 0.08 3.72 8.7 0.98
-1.5 N2 + air 500 0.08 0.84 8.7 0.99
'I n10210 . -kt + Ao . -kt + In[02L; [Oz]t is voltune (tilL) of 02 in the pack
atmosphere at time t (hour) and
1021,, is volume (mL) of 02 in the pack atmosphexe at t . 0 h.
bCalculated half-life (h) . 0.693/k: observed half-life in Table 1.
(2) indicates text missing or illegible when filed
EXAMPLE 2 [0316]
[0315] TABLE 2b
TABLE 2a Oxygen (02) concentration in master packs containing beef
and pork
stored at r C. in 100% nitrogen (N,) atmosphere for seven days.
Description of treatments for beef steaks and pork chops
for experiment I. 02 Concentration (ppm)
Treatment N' Description
Treatment Beef Pork
A 3 Lidded control tray with meat
B 3 Lidded tray containing meat and grid During initial packaging
150-200 150-200
C 3 Lidded tray with meat and absorbent pad A 214
853
D 3 Lidded tray containing meat and 02 scavengers inside the B 334
1150
retail tray C 890 862
E 3 Lidded tray containing meat, grid, and absorbent pad D' 0
0
F 3 Lidded tray containing meat, grid. and 02 scavengers E 201
377
inside the retail tray F* 0 0
0 3 Lidded tray containing meat, absorbent pad, and 02 G" 30 0
scavengers inside the retail tray /V 1560 0
H 3 Lidded tray with meat, grid, absorbent pad, and 02 D 1 x
0 0
scavengers inside the retail tray Fix 0 0
DI 3 Treatment D with 02 scavengers outside the retail tray GI x
102 0
Fl 3 Treatment F with 02 scavengers outside the retail tray H I x
0 0
GI 3 Treatment G with 02 scavengers outside the retail tray
III 3 Treatment II with 02 scavengers outside the retail tray
`02 scavengers inside the retail tray
'Number of retail trays in a master pack. x02 scavengers outside the retail
tray
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[0317]
TABLE 2c
Mean colour, surface discoloration, and retail appearance scores and standard
errors
for pork chops and beef steaks after various treatments.
Beef Pork
Dis- Retail Dis Retail
Treatment Colort" SE" coloration"' SE Appearance:" SE Color"
SE" coloration" SE Appearance:" SE
A 6.75" 0.22 5.58" 0.69 2.001 0.42 2.75 0.22 3.83" 0.74
3.67E 0.75
B 5.50n,c 026 5.50" 0.40 1.92E 0.45 2.75 0.22 3.33" 0.68
4.58 0.72
c 5.00D=c 0.00 5.17" 0.20 2.25E 0.44 3.00B'c 0.00 1.25c
0.22 6.75" 0.22
D**" 5/20D=c 0.20 1.00E 0.00 6.25" 0.22 3.00B=c
000 1.00c 0.00 6.75" 0.22
E 5.75E 0.25 4.67B 0.39 I.92E 0.34 3.25" 0.22 1.00c
0.00 6.50" 1126
F*** 0.09 1.67Ds 0.39 6.25" 0.44 3.08"s 0.15 1.175
0.20 6.60"s 0.26
G+++ 5.00D'c 0.30 1.830"E 0.56 4.75c 0.57 2.830,c
0.20 1.42c 0.25 6.33B 0.25
H.... 6.00" 0.06 3.50' 0.45 3.25 0.38 3.00B.c 0.00 1.17c
0.20 6.83" 0.20
D1* 5.58"J3 0.10 1.81 X 0.62 5.003A=c 0.62 2.36E 0.26
247B 0.94 5.23' 0.26
F1' 0.32 1.92D 0.86 5.00c 0.58 3.00.c 0.00 1.00c
0.00 7.00" 0.00
01" 5.58D 0.29 583" 0.47 1.835 0.36 3.00E4c 0.00 1.08c
0.15 6.92" 0.15
HI" 5.679.c 0.25 1.5 ADS 0.34 5.75" 0.38 3.00Iµc 0.00
1.08c (1.15 6.92" 0.15
'Color scale (pork chop): 0- Completely discolored, 1 = Extremely pale, 2 =
Pale, 3 = Normal, 4- Dark, 5 - Extremely dark; Color scale (beef steak):
0 - Completely discolored, 1 - White, 2 - Pale pink, 3 - Pink, 4 . Pale red, 5
- Bright cherry red, 6 - Slightly dark red, 7 - Moderately dark red, 8 -
Extremely dark red.
"Discoloration scale (pork chop or beef steak): 1 - 0% (none), 2- 1-10%, 3 ..
11-25%, 4 - 26-50%, 5 - 51-75%, 6- 76-99%, 7- 100% (com-
plete).
:Retail appearance scale (pork chop or beef steak): 1 - Extremely undesirable,
2 - Undesirable, 3 - Slightly undesirable, 4 - Neither desirable nor
undesirable, 5 .. Slightly desirable. 6 - Desirable, 7 - Extremely desirable.
*Means in the same colunm bearing a common letter do not differ significantly
(p > 0.05).
**Standard errors of difference.
'''02 scavengers inside the retail tray.
µ02scavengers outside the retail tray.
[0318]
TABLE 2d
Mean values of the chemical states of myoglobin (% met-, % dcoxy-, and % oxy-
myoglobin) and
standard errors of difference for pork chops and beef steaks after various
treatments. =
Pork Beef
% of chemical states of myoglobin % of chemical states of myoglobin
Treatment % met-' SE" % deoxy--= SE % oxy-t." SE % met SE %
deoxy SE % oxy SE
A 26.81A 5.80 24.180.0 5.07 49.01F-t 0.72 57.43'
6.07 0.00E 0.00 42.570x 6.07
13 20.37^ 8.80 24.6204 4.07 55.01F1)-E4 4.79 55.24"
24.16 4.12" 1.80 40.64 23.35
C 5.22B 0.94 42.10" 3.02 52.68RDs 2.16 23.2313Jµc 16.36
1.30 0.65 75.41Bsi`-c 16.93
Dm 0.019 0.01 37.77B.1/4c 3.84 62.22Bssx 3.85 058c
0.05 3.04" 1.40 96.38" 0.95
12 5.44B 2.40 47.90" 3.00 46.66r 1.70 17.7415`c 15.36
2.06D 1.58 80.200A=c 14.53
F*** 0.14B 0.10 35.343sd,c 4.35 64.52B.D.A...c 445 0.00C
0.00 1.219 1.05 98.79" 1.05
G"*" 2.07B 1.80 21.83 7.50 76.10" 8.22 2.118'c
1.82 5.67"s 2.92 92.22"-B 1.62
11"*" 000B 0.00 31.95B=DA4 338 68.053A=c 338 7.838=c
4.46 13.71A 8.80 78.46c 8.03
D1' 000B 0.00 21.07 2.35 78.93" 2.35 2.40BL 1.07
7.12'"-B 1.00 90.48As 0.15
Fl" 0.00B 0.00 28.74Bs-c 4.67 71.26"-B 4.16 2.24'
1.80 5.20" 4.45 92.56"=3 3.79
01' 0.00 0.00 25.56 -c 3.32 74.44'''" 3.32 37.29" 16.24
3.78" 1.48 58.93 S.0 17.71
HI' 6.82 5.90 27.83B-D=c 7.27 65.369'D'A'C 3.78 0.00c
0.00 8.53 A'D 4.23 91.47"J' 4.23
t% oxy- ... 100 - [(% met-) + (% deoxy-)]
*Means in the same column bearing a common letter do not differ significantly
(p > 0.05).
**Standard errors of difference.
*"02 scavengers inside the retail tray.
"02 scavengers outside the retail tray.
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