Note: Descriptions are shown in the official language in which they were submitted.
2038~7~
CONTROLLED ATMOSPHE~E PACKAGE
The present invention relates to controlled
atmosphere packaging, and more particularly to
controlled atmosphere packaging for red-ripe fresh
tomatoes.
There is considerable demand among consumers
for such tomatoes, but getting truly red-ripe tomatoes
to the consumer has proven exceedingly difficult due to
the limited time length of the red-ripe stage and the
particular susceptibility of red-ripe tomatoes to
bruising, rupture, and microbial attack.
Most of the "red-ripe" tomatoes sold to the
consumer are harvested in the mature green stage of
ripening and subsequently exposed to ethylene gas to
initiate ripening off the vine. The tomatoes are then
quickly shipped in bulk to their final destination so
that they will be in the red-ripe stage at the time of
sale to the consumer. Problems with this method include
bruising due to bulk shipping and reduced flavor in the
tomatoes due to picking in the green stage rather than
in the vine-ripe stage.
38,445-F -1-
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Because of these problems, several attempts
have been made to develop suitable controlled atmosphere
packages for storing or delivering tomatoes at more
advanced stages of vine-ripeness. Such a package is
seen in United States Patent No. 4,079,152 to Bedrosian
(Bedrosian). Bedrosian describes controlled atmosphere
packages generally which employ a gas permeable film and
packets of a humectant and of a carbon dioxide absorbing
material. The form of the package per se is not
considered to be ofjjparticular importance, and suggested
forms include a bag which can be sealed or tied by any
conventional means, a wrap for a tray or container which
holds the produce, or as windows in an otherwise
impermeable framework or container. The humectant can
be any of several salts, and the positioning of the
humectant and carbon dioxide absorbing packets in the
package appears not to be of concern.
The types of packages described in Bedrosian
are unsatisfactory in several respects, however. In one
respect, these packages offer very little in the way of
physical protection for the tomatoes in shipping,
handling and storage; as noted earlier, red-ripe fresh
tomatoes are very susceptible to physical damage. In
another important respect, the packages provide no
effective way to manage the humidity of the air
surrounding the tomatoes so that mold can be prevented
from growing.
3 The present invention overcomes these
deficiencies in the known art by providing a controlled
atmosphere, controlled humidity package for red-ripe
38,445-F -2-
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--3--
fresh tomatoes. The package contains at least one
tomato and comprises a protective plastic enclosure
which defines an opening therein. A gas permeable
plastic film is situated about and in air-tight sealment
with the enclosure at the opening therein. The tomato
is situated within the protective enclosure in a
substantially fixed position regardless of the
orientation of the package, but is contacted by the
package over a limited area.
A humectant material is contained within a
packet having water vapor permeable, liquid water
impermeable walls, with the packet in turn being
positioned within the enclosure in a fixed, spaced
relation to the tomato. A substantially uniform
relative humidity is maintained in all regions of the
enclosure by means of the selection and positioning of
the humectant in the enclosure, and by reason of the
limited area of contact between the tomato and package
so that water vapor is not trapped and does not
accumulate in any particular portion of the enclosure.
The present invention will be better understood
on reviewing the detailed description which follows
together with the drawings, in which:
Figure 1 is an isometric view of a controlled
atmosphere, controlled humidity package for red-ripe
tomatoes according to the present invention with
tomatoes therein.
Figure 2, is an exploded isometric view of the
package of Fig. 1.
38,445-F -3-
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Figure 3 is a top view of a tomato.
Figure 4 is an isometric view partly broken
away and fragmented of another embodiment of a
controlled atmosphere, controlled humidity package for
red-ripe tomatoes according to the present invention.
Figure 5 is an exploded isometric view of the
package of Fig. 4.
A controlled atmosphere, controlled humidity
package 10 is shown in Fig. 1 with red-ripe tomatoes
therein. Package 10 comprises a relatively rigid
protective plastic enclosure 15, a packet 22 of a
humectant material, and a film 40. Enclosure 15
comprises a tray 20 and an insert 30. Package 10 is
seen in an exploded view in Figure 2.
Tray 20 defines a chamber 25 which holds one or
more tomatoes 12. Preferably, tray 20 is large enough
to accommodate two tomatoes which weigh from 180 to 230
grams each, which have a diameter of about 3 inches (7.6
cm.), and which have a height of about 2 1/2 inches (6.4
cm.). Package 10 is preferably from 6 to 8 inches (15.2
to 20.3 cm.) in length, from 3 to 5 1/2 inches (7.6 to
14.0 cm.) in width, and from 2 1/2 to 3 1/2 inches (6.4
to 8.9 cm.) in height.
Tray 20 forms an opening 33 to chamber 25 which
is bounded by a tray lip 24. Lip 24 is preferably
3 substantially flat and preferably parallel with the
bottom of tray 20. Lip 24 defines outwardly-extending
flange portions 27 and inner portions 26 in the form of
38,445-F -4_
203~g7J3
localized depressions adapted to receive peripheral
portions of insert 30. When such peripheral portions
are received within inner portions 26, flange portions
27 and insert 30 are preferably coplanar. Tray 20
further defines bottom cradles 28 which receive and
restrict the movements of tomatoes 12 in chamber 25.
A trough 23 is defined in the bottom of tray 20 for
receiving the humectant packet 22, and opens toward
chamber 25 and insert 30.
Package 10 includes means for holding and
maintaining tomatoes 12 in a substantially fixed
position with respect to the remainder of package 10
regardless of the orientation of package 10. In the
particular embodiment shown, package 10 maintains
tomatoes 12 in a substantially fixed position by
providing various surfaces located above, below, and
lateral to tomatoes 12 in the form of a tray 20, the
cradles 28, and an insert 30.
Tomatoes 12, a representative specimen of which
is seen in Figure 3, may rest upside down within tray 20
and package 10 with their stem scars 14 toward the
bottom of package 10 and toward the packet 22. Stem
scars 14 are preferably situated in proximity to the
packet 22, and more preferably are situated within 1
inch (2.54 cm.) of packet 22. Since most of the water
vapor transpiring from a tomato is emitted through the
stem scar, proximity to a packet of humectant m~aterial
allows the water vapor to be absorbed rather than
accumulate to form liquid water on the surface of the
tomato in the area of the stem scar. Buildup of liquid
water is undesi.rable because it can accelerate mold
formation.
38,445-F -5-
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Insert 30 preferably performs several functions
in package 10 including functioning as an internal lid
for tray 20, preventing contact between tomatoes 12 and
film 40, protecting tomatoes 12 from physical damage
associated with stacking two or more packages 10 upon
one another, and assisting in maintaining tomatoes 12 in
a substantially fixed position within package 10 whereby
contact between the tomatoes or between the tomatoes and
the film 40 is avoided, and whereby the relationship
between the packet 22 and the stem scar of the tomatoes
may be effectively maintained.
Insert 30 protects tomatoes 12 from physical
damage associated with stacking two or more packages 10
upon one another. Insert 30, being physically supported
at its periphery by lip 24 at inner portions 26, is
sufficiently rigid in this context to be capable of
supporting one and preferably a stack of packages 10 in
storing, shipping and display. Insert 30 may or may
not be sealed to lip 24, tray 20, or any other component
of package 10.
Insert 30 further assists in maintaining
tomatoes 12 in a substantially fixed position within
package 10, by defining depressions 32 in the surface 31
of insert 30 which contact the bottom ends of tomatoes
12. Depressions 32 work in this respect in conjunction
with cradles 28 and surfaces of the tray 20 lateral to
tomatoes 12. It is understood however, that film 40 may
3 be utilized in lieu of insert 30 to help hold tomatoes
12 in a substantially fixed position. Cradles 28, which
receive most of the weight of tomatoes 12 when package
10 is in an upright position, are preferably configured
to provide adequate structural support to tomatoes 12
with minimal surface contact therebetween to minimize
38,445-F -6-
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the possibility of bruising. Further, it is preferable
to minimize contact between the surfaces of tomatoes 12
and any other surfaces of package 10 for the same
reason.
Insert 30 preferably also prevents contact of
the film 40, described hereinafter, with tomatoes 12.
Insert 3G defines one or more openings 34. Openings 34
allow interchange and permeation of gases through film
40 between chamber 25 and the atmosphere surrounding
package 10. The openings 34 are preferably positioned
so that the film 40 cannot draw down and contact
tomatoes 12 situated in c.hamber 25. Insert 30 and tray
20 are designed and adapted to fit together so that an
opening is always defined by the combination of the two,
whereby this interchange and permeation can occur.
Insert 30 is comprised of a relatively rigid
thermoplastic material, and is preferably comprised of
the same thermoplastic material as tray 20. Suitable
thermoplastic materials include polystyrene, styrene-
butadiene copolymers and blends of polystyrene with
styrene-butadiene copolymers, polyvinyl chloride,
polyethylene terephthalate, polyethylene terephthalate-
glycol, or a cellulosic material such as celluloseacetate propionate.
Insert 30 may be formed by any conventional
plastic fabrication technique such as thermoforming or
injection molding. Preferably, insert 30 is
thermoformed, and is 5 to 25 mils (0.127 to 0.635 mm.)
thick. The lateral dimensions of insert 30 are dictated
largely by the length and width of the upper portions of
tray 20 and lip 24.
38,445-F _7_
7 ~
--8--
Film 40 forms an airtight, water-tight seal
over the top of insert 30 and tray 20. Film 40 is
preferably sealed to tray 20 at lip 24, and mast
preferably heat sealed thereto.
Packet 22 is held in substantially fixed,
spaced relation to the tomatoes 12 in a package
regardless of the orientation of the package 10.
The size of packet 22 and the amount of
humectant material which should be contained therein is
determined by the number and size of tomatoes 12 and
their water vapor transpiration rates, as well as by the
positioning of the packet 22 relative to the stem scars
of the tomatoes 12. Preferably there is enough of the
humectant material in the packet 22 to absorb the
transpired water vapor from the tomatoes 12 for 7 to 14
days, and more preferably for 14 to 21 days.
Package 10 may further comprise an overlay 50
of a material capable of receiving printed indicia.
Overlay 50 may be comprised of a plastic or a paperlike
material capable of receiving printed indicia, but is
most preferably a paperlike material. Overlay 50 may
have a degree of gas permeability sufficient to provide
the desired gaseous composition within chamber 25, or
may define one or more openings 52 therein to aid in gas
permeation through film 40.
Overlay 50 is preferably heat sealed to film 40
opposite the lip 24, and preferably has lateral
dimensions sufficient to cover the entirety of lip 24 of
tray 20. Preferably, overlay 5a will be comprised of a
material heat sealing compatible with film 40.
38,445-F -8-
2~3~7~
g
Another embodiment of the package of the
present invention is illustrated in Figures 4 and 5.
Package 60 comprises a relatively rigid protective
plastic enclosure 65, a packet 72 of a humectant
material, and a film 90. Enclosure 65 comprises a tray
70 and an insert 80. As in package 10, tray 70, insert
80, film 90, and an overlay 100 are stacked
sequentially. Package 60 defines a chamber 75 wherein
tomatoes 16 can be situated. Tray 70 defines curved
surfaces 78 which curve downwardly inward. Curved
surfaces 78 cradle and receive tomatoes 16 when package
60 is in an upright position. A packet 72 of a
humectant material is situated in a trough 73 in the
bottom of tray 70. Insert 80 acts as an internal lid
for package 60 and is situated about the opening at the
top of the tray 70 upon flanges 76 and 77. The shape of
insert 80 and its arrangement with respect to tray 70
provide openings 71 where the various gaseous components
of the ambient air environment and chamber 75 can
20 interpermeate through film 90. Film 90 is heat sealed
to a lip 74 of tray 70. Overlay 100 is heat sealed
around its edges to film 90 opposite the lip 74.
Overlay 100 may have a degree of gas permeability
25 sufficient to provide the desired gasous composition
within chamber 75, or may define one or more openings
102 therein to aid in gas permeation through the film
90. The materials for the components of package 60 can
be those employed for package 10.
3o
Trays for the package of the present invention
commonly will be comprised of a thermoplastic resin, and
can also be made utilizing any conventional plastic
fabrication technique such as thermoforming or injection
molding. Suitable thermoplastic resins for the tray
38,445-F -9-
2~38~70
1 0--
include polystyrene, styrene-butadiene copolymers and
blends of polystyrene with styrene-butadiene copolymers,
polyvinyl chloride, polyethylene terephthalate, or
polyethylene terephthalate-glycol. Polyvinyl chloride
is most preferred. The tray is preferably from lO to 25
mils (0.254 to 0.635 mm). thick, and most preferably
from 15 to 20 mils (0.381 to 0.508 mm.) thick. The tray
is preferably sufficiently transparent so that the
consumer may inspect the tomatoes through the tray
before their purchase.
Films useful in the present invention are
comprised of a relatively non-rigid thermoplastic
material conventionally extruded by either blown or cast
film methods. The thermoplastic material comprising the
film must also be heat sealable to the thermoplastic
material comprising the lip of the tray. Preferred
films are those that are permeable to both oxygen and
carbon dioxide. Preferably the film will be 4 to 6, and
more preferably 6 to 8 times more permeable to carbon
dioxide than oxygen. A most preferred film has an
oxygen permeance of about 1,000 to about 1,500 cc/lO0
sq. in.-day-atmosphere and a carbon dioxide permeance of
8,000 cc/100 sq. in.-day-atmosphere.
Suitable materials for the films include
copolymers of styrene and butadiene, polyethylene
homopolymers, copolymers of ethylene and vinyl a~etate,
and coextrusions of these materials. A particularly
3 preferred film comprises a single layer of a copolymer
of ethylene and vinyl acetate. The thickness of the
film is dependent upon the material from which it was
formed, but the film will normally be from 0.1 to 5 mils
(0.0025 to 0.127 mm.) thick. The most preferred
3~,445-F -lO-
203~7a
--1,
thickness of film 40 is from 0.5 to 2.0 mils (0.0127 to
0.0508 mm.).
Selecting a film with the desired level of
carbon dioxide permeability allows the packages of the
present invention to maintain the desired steady state
levels of C02 within the chamber and around the tomatoes
without a C02 absorber in the chamber, although such an
absorber may be added to assist the film if desired.
The packages of the present invention provide a
carefully controlled environment at steady state of
preferably from 70 to 90, and more preferably from 70 to
78 percent relative humidity. The oxygen concentration
within the chamber at steady state is preferably from 2
to 10, and more preferably from 2 to 4 percent by
volume. The carbon dioxide concentration at steady
state is preferably less than 5 percent, and more
preferably from 2 to less than 4 volume percent. The
below ambient levels of oxygen reduce the respiration
rate, and thus the rate of ripening of the tomatoes.
Carbon dioxide levels in excess of about 5 volume
percent may make the tomato susceptible to cellular
damage, but some C02 presence is desirable to enhance
the viability and longevity of the tomato. The relative
humidity and gaseous concentration provided by a given
package will often vary for different types of tomatoes
because tomatoes differ in their respiration and/or
transpiration rates. Thus, the preferred and most
3 preferred ranges for relative humidity and gaseous
concentrations will vary somewhat according to the type
of tomato.
The package reaches steady state oxygen and C02
concentrations after the tomatoes have been packaged for
38,445-F
203897~
-12-
about two days. Steady state concentrations may also be
achieved by gas flushing when the package is packed and
sealed.
Maintenance of a lower than ambient oxygen
content within the chamber prolongs the ripening process
in the tomatoes, as described above. The slowing of the
ripening process in turn lengthens the duration of the
desirable red ripe stage. The desirable levels of
oxygen and carbon dioxide can be maintained in the
chamber for preferably 7 to 14 days and more preferably
for 14 to 21 days, after which point the quality of
tomatoes can be expected to decline. If the package is
maintained at below ambient temperatures such as about
50-60 degrees F (10-15.5 deg. C), the fruit may be
maintained in the red ripe stage for still longer
periods because of the lower respiration rate of the
tomatoes at lower temperatures.
2Q The steady state levels for oxygen and carbon
dioxide within the chamber are determined by the
permeability of the film for each of them. These
permeabilities are determined by the characteristics of
the film and by the partial pressure gradients for each
of oxygen and carbon dioxide across the film. The
greater the partial pressure gradient between the
chamber and the ambient environment outside the package
for either gas, the greater the transport through the
film in one direction or the other.
3o
At steady state, the rate of permeation of
oxygen through the film and into the chamber will
preferably about equal the projected rate of respiration
of oxygen by the tomatoes, and the projected rate of
permeation of carbon dioxide through the film and out of
38,445-F -12-
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the chamber will preferably about equal the projected
rate of respiration of carbon dioxide by the tomatoes.
The humectant material contained within packet
22 preferably maintains the desired relative humidity of
package 10 at a generally constant level. Packet 22
comprises a humectant material and a patch material
which is water vapor permeable but substantially liquid
water impermeable. Suitable patch materials include
cellulose acetate and Tyvek* (trademark of E. I. DuPont
de Nemours & Co.) nonwoven polyethylene fabric.
Suitable humectant materials include
conventional humectant or desiccant materials such as
the chloride salts, sulphate salts, silica gel, or
activated alumina. Preferred humectant materials
exhibit only negligible absorption of water vapor up
until about 70 percent relative humidity. Preferred
materials will maintain levels of 70-90 percent, and
especially 70 to 78 percent relative humidity in the
chamber of the package at normal room temperatures, and
will further preferably maintain these levels over a
temperature range of from 50 to 90F (10 C to 32.2 C).
Preferred humectant materials include sodium chloride,
mannitol, and sorbitol. The most preferred material is
sodium chloride due to its low cost, low toxicity,
familiarity to consumers, and excellent performance.
Relative humidities of between about 70 and
about 90 percent are preferred in packages of the
present invention because levels below about 70 percent
may result in dehydration of the tomatoes and levels in
excess of about 90 percent may result in mold growth and
liquid water buildup in the package and on the tomatoes.
38,445-F -13_
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-14-
As indicated above. the packets of humectant
material are located in proximity to and preferably
within about one inch of the stem scars of the packaged
tomatoes. The packet of humectant material preferably
does not contact the stem scars ? however, because such
contact may operate to se~l in water vapor in the area
of the stem scar and to promote mold growth in the area
of the stem scar. Further, the consumer's view of the
stem scar may be obstructed.
Packages of the present invention preferably
maintain a substantially uniform relative humidity and
gaseous composition within all regions of the chamber.
A substantially uniform relative humidity means that the
l~ humidity varies by no more than 20 and preferably by
less than 10 percent from any given region of the
chamber to another. The chamber is designed to hold the
tomatoes in a substantially fixed position relative to
the rest of the package 10 regardless of the package's
orientation, but at the same time permits the free flow
of gases from one part of the chamber to another so that
localized concentrations of water vapor or condensate
are kept to a negligible extent. Preferably, no region
of the chamber is sealed off from other regions by
contacting surfaces of the tomato or tomatoes and the
package. Further preferably, no surface of the package
is in direct contact with the stem scar to minimize
localization of water vapor and/or condensate in this
critical area. The proximity of the absorber packet to
the stem scars of the tomatoes also aids in minimizing
localization of water vapor and~or condensate, and thus,
in maintaining a substantially uniform relative humidity
throughout the package.
38,445-F _14_
2~38~70
-15-
Inserts may be modified in other embodiments of
the present invention to provide a compartment for a
humectant material as the functional equivalent of a
packet of humectant material, or a packet of the
humectant material may simply be attached to the
underside of an insert. The compartment in an insert
may define a microporous or other water vapor permeable
layer on the underside of the insert so that the
humectant material will be in close proximity to but
will not contact the stem scars of the tomatoes. With
such a compartment defined within the insert or with a
packet attached to the underside of the insert, the
tomatoes may be situated right side or stem scar up in
the package.
Packages of the present invention also define
means for maintaining the separation and lack of
physical contact of the tomatoes regardless of the
orientation of the package. In package 60, the
separation and lack of physical contact of tomatoes 16
is maintained by holding and maintaining tomatoes 16 in
separate positions by various surfaces located above,
below, and lateral to tomatoes 16 in the form of tray
70, curved surfaces 78 of tray 70, and insert 80.
Packages of the present invention are
configured to minimize contact between the surfaces of
the tomato or tomatoes and the surfaces of the package
in order to minimize the possibility of bruising, in
3 addition to providing avenues for the circulation of
gases in the chamber. The rigid packages are configured
in this respect so that the tomato or tomatoes are held
in a substantially fixed position by contact between the
surfaces of the tomatoes and the package at multiple
points and regions around the tomato. Preferably, less
38,445-F _15_
2~38970
-16-
than 20 percent of the total surface area of the tomato
or tomatoes is in physical contact with the package
regardless of the orientation of the package. Further
preferably, any given point or region of contact
comprises no more than 10 percent of the total surface
area of the tomato or tomatoes regardless of the
orientation of the package.
It is understood that the packages of the
present invention may be used with perishable fruits
other than tomatoes.
A process for packaging a tomato in the manner
of the present invention comprises providing a package
which defines a chamber therein, placing one or more
tomatoes into the chamber, maintaining the tomatoes in a
substantially fixed position relative to the package
regardless of the orientation of the package,
maintaining a substantially uniform 70-90% relative
humidity in the chamber at steady state, and maintaining
a steady state gaseous composition in the chamber of
from 2 to 10 volume percent of oxygen and less than 5
volume percent of carbon dioxide. It is preferable if
the chamber is kept at a steady state 70 to 78 percent
relative humidity for preferably 7 to 14 days, more
preferably for 14 to 21 days. Preferably, the desired
relative humidity levels are maintainable over a
temperature range of from 50F (10 deg. C.) to 90~F (32.2
deg. C.) in the chamber. It is also preferable if the
steady state gaseous composition in the chamber is kept
at from 2 to 4 volume percent of oxygen and from 2 to
less than 4 percent by volume of carbon dioxide for
preferably 7 to 14 days, and more preferably for 14 to
21 days. In a preferred embodiment, the process further
comprises maintaining a physical separation and lack of
38,445-F -t6-
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-17-
contact between tomatoes (if there are two or more
tomatoes in the package) regardless of the orientation
of the package.
The example below further illustrates the
present invention.
EXAMPLE
A package of the present invention, similar to
the embodiment shown in Figures 4 and 5, was tested for
its performance in maintaining proper chamber
environment and the saleability of red-ripe tomatoes
packaged therein (Group I). The performance of a second
package design (Group II) was compared to that
associated with Group I. The packages of Group II
differed primarily from those of Group I in that those
of Group II did not contain a packet of humectant
material, and in that the film was perforated with holes
of about 1 cm. in diameter in each of the four corners
of the package to allow exchange of air between the
chamber of the package and the environment in which the
package was situated. The performance of the packages
of Group I were also compared with that of a control
group of conventionally boxed red-ripe tomatoes (Group
III). The atmosphere in the chambers of both the
packages of Group II and the boxes of Group III was
largely uncontrolled.
Each package in Groups I and II contained two
red-ripe tomatoes. The film in the Group I packages was
like that of film 90, was formed from ELVAX 3190
(marketed by E. I. du Pont deNemours & Company) brand
ethylene-vinyl acetate copolymer resin, and was 1.2 mils
thick. The film used in the packages of Group II was an
38,44~-F -17-
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-18-
E~A-coated polyester, and the EVA-coated polyester was
1.0 mil thick. The humectant material was 15 grams of
NaCl contained within a Tyvek* (trademark of E.I. du
Pont De Nemours & Co.) pouch.
The tomatoes tested as part of the various
groups were harvested vine-ripe in Florida, and were
subsequently washed with soapy water, rinsed with 5.0
ppm chlorinated water, and air-dried. The tomatoes were
placed in the packages described above for Groups I and
II, and placed in corrugated tomato boxes in Group III.
There were 96 packages of tomatoes in Group I and 72
packages in Group II, and 111 tomatoes total in Group
III. Each package in Groups I and II contained tomatoes
weighing a total of about 380 grams.
The packages of Groups I and II and the boxes
of tomatoes of Group III were packed in corrugated
cases, with 24 packages to a case in two stacked levels
of twelve. The cases were shipped from Georgia to
Alabama to Indiana, and examined there after 7 days from
the time of initial packaging. The cases were then
shipped to Michigan, and examined after 14 days from the
time of initial packaging.
The tomatoes were examined at 7 days and 14
days for saleability. A tomato was deemed saleable if
it had no bruises, cuts, or mold formation visible to
the naked eye. The packages of Groups I and II were
examined for saleability as a unit. If one of the two
tomatoes in a package was deemed unsaleable, then the
entire package was deemed unsaleable. The tomatoes of
Group III were examined for saleability individually.
38,445-F -18-
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-19-
All tomatoes tested were deemed saleable prior to their
placement in the described packages and boxes.
For the packages of Group I, 96.9 percent were
deemed saleable after 7 days, and 54 percent were
saleable after 14 days. For the packages of Group II,
64 percent were saleable after 7 days, and 30 percent
were saleable after 14 days. For the individual
tomatoes of Group III, 80 percent were saleable after 7
days, and 26 percent were saleable after 14 days. Thus,
the packages of Group I according to the present
invention offer significantly increased shelf life over
the uncontrolled atmospere packages of Group II and
cell-divided boxes of Group III.
The relative humidity within the chambers of
the packages of each of Groups I and II was also
compared. The packages of Group I had a mean relative
humidity of 72.1 percent after 9 days. The packages of
Group II had a mean relative humidity of 79.5 percent
after 9 days. The packages of Group I made according to
the present invention offer a lower humidity level than
the uncontrolled atmosphere packages of Group II while
still being within preferred relative humidity ranges.
A lower relative humidity lowers the likelihood of
formation of mold on the tomatoes. It should be noted
that the type of tomatoes selected for the tests in this
Example are known to have lower than average
transpiration rates for tomatoes in general; it is
3~ accordingly expected that greater differences in the
relative humidities associated with the packages of
Groups I and II would be observed with most tomatoes
generally.
38,445-F -1y-
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-20-
The oxygen and carbon dioxide concentrations
within the chambers of the packages of Group I were also
analyzed by gas chromatograph. The packages of Group I
which exhibited a high degree of sealing between the
film and the lid of the tray of the package, as
evidenced by the presence of drawdown in the package,
had a mean oxygen concentration of 2.3 volume percent
and a mean carbon dioxide concentration of 3.7 volume
percent after 7 days. Thus, the packages of Group I
maintained the desirable, substantially below ambient
levels of oxygen and desirable, controlled levels of
carbon dioxide.
While specific embodiments have been shown and
described herein of controlled atmosphere packages and a
process for controlled atmosphere packaging, it will be
appreciated that these embodiments may be modified in
several respects, for example, while still being fairly
within the scope of the teachings and principles herein
set forth.
3o
38,445-F -20-
