Note: Descriptions are shown in the official language in which they were submitted.
97Si
This invention relates to a process and a composition
for establishing and maintaining good color in fresh meat,
fresh poultry and fresh fish.
The literature relating to the establishment and main-
tenance of good color in fresh meat, fresh poultry and fresh fish
includes U. S. Patents 3,851,808 and 3,930,0~0, and A. El Badawi,
R. Cain, S. Samuels, and A. Anglemeier, Color and Pigment_Stability
of Packaged ~efrigerated Bee, Food Technology, pp. 159-163 (~ay,
1964) and T. Besser and A. Kramer, Changes in Quality and
Nutritional Composition of Foods Preserved by ~,as Exchange, 37
.
~ournal of Food Science, po. 820-823 (1972) and which describe
the use of certain modified gaseous atmospheres for providing
and maintai~ing good color in fresh meat, fresh poultry and
fresh fish. None, however, discloses the modified atmospheres
of this invention or the highly simplified process of this
invention for doing these tasks.
In accordance with this invention, good color is
established and maintained in fresh meat, fresh poultry and
fresh fish; In fresh meat and poultry, the process comprises
subjecting meat, poultry, or both to an atmosphere sufficiently
low in oxynen concentration to change a substantial portion of
the oxymyoglobin on and below the meat or poultry surface to
reduced myoslohin, then subjecting the fresh meat and
fresh poultry to a modified atmosphere including sufficient
carbon monoxide by volume to convert a substantial portion
of the reduced myoglobin to carboxymyoglobin to a depth of
not more than about 0.375 inch, preferably not more than about
0.25 inch, below the surface of the fresh meat or fresh poultry.
Until the conversion of the reduced myoglobin to carboxymyoglobin
is complete, the modified atmosphere preferably includes as
little oxygen as possible, and as little as possible of any
obher substance that would inhibit conversion to carboxymyoglobin.
Preferably, the modified atmosphere will include at least
about 10% by volume carbon dioxide and the balance substantially
all molecular nitrogen and/or other inert gases. Some oxygen
may be present during this conversion, but preferably in
amounts not greater than abou-t 10% by volume, and more
preferably, in amounts not greater than about 5~ by volume.
Increasing the concentration of oxygen before the conversion
is complete simply tends to inhibit the conversion to
carboxymyoglobin as the oxygen competes for the reactive
sites in the reduced myoglobin. A substantial portion is
converted from reduced myoglobin to carboxymyoglobin when
the naked eye can see a distinct overall color change from
the purple color of reduced myoglobin to the bright red color
- of carboxymyoglobin.
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The amount of carbon monoxide sufficient to effect
such conversion to a depth not greater than about 0.375 inch, ;'
and preferably not greater than about ().25 inch, varies
depending upon the method employed to convert oxymyoglobin to
reduced myoglobin. This method may be the use of a reducing
agent, application of a vacuum, flushing with an inert gas
such as nitrogen, or some other method. Thus, where a reducing
agent such as ascorbic acid is used to form the atmosphere
low in oxygen concentration, the carbon monoxide concentration
may range from about 0.10% to about 3%. By contrast, where
nitrogen flushing is used for this purpose, the carbon monoxide
concentration may range frGm about 0.10% to about 1.5%,
more preferably about 1%.
Similarly, the process of this invention comprises
subjecting fresh fish to an atmosphere sufficiently low in
oxygen concentration to change a substantial portion of the
oxymyoglobin~oxyhemoglobin on and below the surface of the
fresh fish to reduced myoglobin/hemoglobin, then subjecting
'the fresh fish to a modified atmosphere lncluding sufficient .;
carbon monoxide by volume to convert the reduced myoglobin/
hemoglobin to carboxymyoglobin/carboxyhemoglobin on and below
the surface of the fresh fish.. Until the conversion of the
reduced myoglobin/hemoglobin to carboxy~yoglobin/carboxyhemoglobin
is complete, the modified atmosphere preferably includes as
little oxygen as possible, and as little as possible of any
other substance that w.ould inhibit conversion to carboxymyoglobin/
carboxyhemoglobin. Preferably, the modified atmosphere will
include at least about 10~ by volume carbon dioxide and the
balance substantially all molecular nitrogen and~or other inert
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gases. Some oxygan may be present during this conversion~ but preferably in
amounts not greater than about 10% by volume, ancl more preferably, in amounts
not greater than about 5% by volume. Increasing the concentration of oxygen
before the conversion is complete simply tends tc) inhibit the conversion to
carboxymyoglobin/carboxyhemoglobin as the oxygen competes for the reactive sites
in the reduced myoglobin/hemoglobin. A substantial portion is converted from
reduced myoglobin/hemoglobin to carboxymyoglobin/carboxyhemoglobin when the
naked eye can see a distinct overall color change from the purple color of
reduced myoglobin/hemoglobin to the bright red color of carboxymyoglobin/
carboxyhemoglobin. For fresh fish, sufficient carbon monoxide is generally
in the range of about 0.10% to about 1.5%, more preferabIy from about 0.10% to
about 1%, but these amounts may vary with the nature of the Eish treated, the
conditions to which the fish was exposed before being subjected to the process
of this invention, and the method used to reduce oxymyoglobin/oxyhemoglobin to
reduced myoglobin/hemog:Lobin.
The new process is particularly important and effective where the fresh
meat, fresh poultry and fresh fish is maintained under refrigerated conditions,
typically a temperature in the range of about 29 F. to about ~0 F. In
commercial practice, the ambient temperature may be somewhat lower (e.g.,
26-27F.) without completely freezing the fresh meat, fresh poultry and fresh
fish.
Subjecting fresh meat, fresh poultry and fresh Eish to an atmosphere
low in oxygen concentration converts the oxymyoglobin, which is red in color, on
the fresh meat and fresh poultry, and the oxymyoglobin/oxyhemoglobin on the
surface of fresh fish, which are also red in color, to the purple-colored
reduced myoglobin and reduced myoglobin/hemoglobin, respectively. Subjecting
the fresh meat, fresh poultry and fresh fish thereafter to the carbon monoxide-
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containing modified atmosphere converts the reduced myoglobin and reduced
myoglobin/hemoglobin to carboxymyoglobin and carboxymyoglobin/carboxyhemoglobin,
respectively, both of which are attractively red in color, and are stable under
refrigerated conditions for long periods of time, such as two to four weeks.
During or following treatment in accordance with the new process, the
fresh meat, fresh poultry and fresh fish may be maintained in a modified
atmosphere including, by volume, about 10% to about 85% carbon dioxide, which
inhibits growth of slime- and odor-producing organlsms, and the balance
substantially all nitrogen (molecular N2) and oxygen ~molecular 2) The
oxygen is preferably present in an amount as low as possible and preferably in
the range of 0% to about 30%. This modified atmosphere may be applied, in
whole or in part, during the conversion of reduced myoglobin, in meat and
poultry, and reduced myoglobin/hemoglobin, in flsh, to carboxymyoglobin and
carboxymyoglobin/hemoglobin, respectively. Thus, in addition to carbon
monoxide, that modified atmosphere may include at least about 10% carbon
dioxide. However, the oxygen concentration should be as low as possible until
conversion to the reduced myoglobin or reduced myoglobin/hemoglobin is complete.
Again, the fresh meat, fresh poultry and fresh fish should be refrigerated,
typically meaning
maintenance in a temperature range of about 29~. to about 40F.,
preferably about 29F. to about 33F. Meat, poultry and ish
maintained under these conditions will retain the good color
produced by the new process for three to four weeks or even
S longer.
Alternatively, following treatment in accordance
with the new p,rocess, the fresh meat, fresh poultry or fresh
fish may be frozen and maintained in that state
until ready for sale, consumption or other use. If frozen, the
meat, poultry and fish will retain the red color of carboxymyoglobin
and carboxyhemoglobin, and the carbon dioxide containing modi,fied
atmosphere need not be applied until the meat, poultry or fish is
thawed. ~1eat, fish and poultry freeze at temperatures below about
29F. at a pressure approximating atmospheric.
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The process of this invention works on all kinds
o~ fresh meat and fresh poultry, including beef ! pork, veal,
lamb, mutton, chicken, turkey and game such as venison,
pheasant, quail, and duck. The meat may be proc~ssed or may
S be in the form of carcasses, primals te.g., quarters), subprimals
(e.g., top round), or retail cuts, and may be partially or
wholly co~minuted or mixed. The process is also effective
on whole fish,fillets, and other forms that fish take, and
on wide varieties of fish including salmon, sole, bass, trout,
cod , and whitefish.
Producing an atmosphere of low oxygen concentration
may be effected in any one of several ways, including placing
the Eresh meat, fresh poultry and fresh fish uncler an inert
~aseous atmosphere containing a low concentration of oxygen.
For example, al~ atmosphere high in nitrogen concentration,
such as an atmosphere containing about 90% to about 100
nitrogen, by volume, for a period of time from about 15
minutes to about 2-3 hours, has proved effective for this
purpose. Alternatively, the meat, poultry or fish may be
subjected to vacuum treatment or may be treated with reducing
agents such as ascorbic acid under conditions and for a time
sufficient to convert oxymyoglobln and oxyhemoglobin to reduced
myoglobin and reduced hemoglobin, respectively. In general,
a low oxygen concentration means a concentration of less than
about 1~ by volume, more preferably, less than about 5
by volume, and as close to zero percent as practicable.
The modified atmosphere used in effecting conversion to
carboxymyoglobin in meat and poultry and to carboxymyoglobin/
carboxyhemoglobin in fish includes, by volume, suficient carbon
monoxide, broadly about 0.10% to about 3% for fresh meat and poultry,
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more preferably about 1% where the ~resh meat i5 bee~, to assure
that the conversion o~ reduced myoglobin to carboxymyoglobin
does not penetrate below the surface of the fresh ~eat to a
depth of ~oxe than about 0.3i5 inch, preferably not more than
about 0.25 inch. Preferably, about 0.10% to about 1.5% carbon
monoxide is used for fresh fish to assure that the conversion
of a substantial portion of the reduced myoylobin/hemoglobin to
carboxymyoglobin/carboxyhemoglobin at the surface of the fresh
fish is effected. Optim~ amounts of carbon monoxide for
different varieties of meat, poultry and fish vary depending
upon the nature of the meat, poultry or fish, the method used
to deoxyyenate oxymyoglobin and oxyhemoglobin, and the conditions
under which the meat or fish was maintained before being
subjected to this new process.
The following examples illus-trate that the new process
establishes and maintains good color in many varieties of
fresh meat, poultry and fish and maintains that good color
over extended storage conditions if the fresh meat, poultry
and fish are maintained under the modified atmosphere of
this invention, or if the fresh meat, poultry and fish are
frozen. In the examples, all gas percentages are by volu~e
unless otherwise stated~
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EXAMPLE
.
One round beefsteak weighing about 0.5 pound was
~laced in a 10-liter desiccator and nitrogen was fed to the
desiccator until the nitrogen concentration reached about
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98~, and the oxygen level in the desiccator dropped to about
2%. The desiccator was left in this condition for about
~ne hour until the color on the surface of the beef changed
from the red of oxymyoglobin to the purple oi reduced myoglobin.
Carbon monoxide was fed to the desiccator until the concen- _
tration reached about O.S~ by volume, a~d was let on the
meat for two days. After two days, the beef had absorbed
nearly al1 of the carbon monoxide, the beefsteak surface had
assumed the red color of carboxymyoylobin, and that color
penetrated to a depth of about 0.125 to about 0.25 inch below
the surface of the meat.
The desiccator was then filled with a modified
atmosphere including about 55~ carbon dioxide,
about 16% oxygen, and the balance substantially all nitrogen.
Six days later, the beefsteak retained its good red color,
and the carboxymyoglobin color had penetrated no more deeply
than it had at the end of two days.
A second round beefsteak weighing about 0.5 pound
was dipped in a 1% ascorbic acid solution, and maintained in
~0 the acid for about ten minutes after which the meat color
had changed from red (oxymyoglobin) to purple (reduced myoglobin).
This steak was then placed in a 10-liter desiccator, and the
- desiccator was filled with an atmosphere comprising 1.0% t
oxygen, about 2.5% carbon monoxide and the balance substantially ~:
all nitrogen. After two days of storage, the steak had
changed from purple to red (carboxymyoglobin), and the carboxy-
myoglobin had penetrated to a depth of about 0.25 inch below
the surface of the meat.
Therea~ter, an atmosphere consisting essentially of
about 55~ carbon dioxide, about 15% oxyge~, and the balance ~
. substant~ally all nitrogen was fed to the desiccator, and ~.
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the desiccator was so maintained for six days. After this
period, the meat retained its good color, and the carboxy-
myoglobin had penetrated no more deeply into the meat than
it had at the end of the two-day period.
EXA~lPLE II_
Each of five pieces of beef roundsteak weighing about
0.5 pound was placed in a separate lO-liter desiccator, and
the desiccator was flushed with nitrogen to raise the
nitrogen concentration to nearly 100%, and to reduce the
oxygen level in the desiccator to near 0%. Each piece of
beefsteak was maintained for one hour under this reduced
oxygen atmosphere, ater which each steak surface had changed
from red to purple in color, indicating that the oxymyoglobin
on the beef surface had changed to reduced myo~lobin.
.
Each desiccator was then ~illed with carbon dioxide
to a volume of about 70%, and carbon monoxide was added
in amounts of lO0, 200, 300, 400 and 500 cc to the five
desiccators, respectively, to give a residual range of about
0.5% to about 3~ carbon monoxide in the five different
desiccators. (Although the amounts of carbon monoxide added
appear to constitute about l, 2, 3, 4 and 5% carbon monoxide,
some carbon monoxide is apparently rapidly absorbed by the !,,
meat, reducing the measurable carbon monoxide content to the
leveis indicated.)
'
After storage under these conditions for seventeen
days at 34F.~ all beef attained and maintained the attractive
red color of carboxymyoglobin, and none o the treated beef
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had spoiled. By contrast, steak held in ~ir at 34~. for
the same period plainly had spoiled and had assumed the
unattractive brown color o metmyoglobln. However, the
formation of carboxymyoglobin had penetrated to depths
greater than about 0.25 inch in all desiccators other than that
to which 100 cc of carbon monoxide was added. These results
indicate that the preferred c~ncentration of carbon monoxide
for attaining and maintaining good red beef color is preferably
not more than about 1% and that carbon dioxide inhibits slime-
and odor-producing organisms.
EXAM~L~ III
Each of eight 100-gram chunks of beef was placed into
a separate 10-liter desiccator and partial vacuum was pulled
on each desiccator wlth an aspirator. Fifty and 100 cc of
carbon monoxide were added to each of two desiccators
immediately after vacuum was pulled. The same quantitles
were added to two other desiccators 15 minutes after vacuum
was pulled, to two others 30 minu-tes after vacuum was pulled,
and to the final two desiccators 60 minutes after vacuum was
pulled.
Twenty-four hours later, high carbon dioxide concentrations,
ranging from 70% to 85% by volume, were added to all the
desiccators. The oxygen content of each desiccator rose to
about 6-7% as the vacuum in each desicc~tor dissipated. The
beef was held fifteen days at a temperature of 33-34F.
under these conditions. Application of the vacuum to each desiccator
- turned the meat color from the bright red of oxymyoglobin to
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the reddish purple of reduced myoglobin, indicating that the
oxygen haa been removed from the oxymyoglobin at the beef's
surface by the vacuum treatment.
~11 of the meat samples receiving a 50 cc treatment of ---
carbon monoxide (0.5~ carbon monoxide by volume) attained only
fair color after ]5 days of storage. The meat receiving 100 cc
of carbon monoxide (1% carbon monoxide by volume) attained and
retained good red carboxymyoglobin color at the end of the 15-
day storage period. The time of application oE carbon monoxide
after vacuum treatment had no observable effect. This demonstrates
that where vacuum is used to convert oxymyoglobin to reduced
myo~lobin before treatment with carbon monoxide, low concentrations
of carbon monoxide may be used to produce carboxymyoglobin on
and below the meat surface.
E ~ ~LE IV
Each of 12 chunks of beef wei~hing about 100
grams was placed in a separate 10-liter desiccator. Each
desiccator was flushed with nitrogen for five minutes to raise
the nitrogen level to near 100% and to reduce the oxygen
level to near zero. Thereafter, carbon dioxide was fed to each
desiccator until the content reached about 65% by volume. Then,
10 cc, 25 cc, 50 cc and 100 cc, respectively, of carbon
monoxide were added to four different desiccators, to produce
carbon monoxide concentrations of 0.1%, 0.25Q, 0.5~ and 1%,
respectively. Fifteen minutes later, four other desiccators
were similarly treated and 60 minutes later, the last four
desiccators received the same treatment.
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All samples were thereafter held two weeks at 33-34F.
After two weeks, all beef treated with 1% carbon monoxide had
excellent color, regardless of the time period elapsed after
flushing with nitrogen. Beef treated with 0.5% carbon monoxide
one hour after flushing had comparable color after two weeks,
but bee~ treated 15 minutes after flushing had only fair color,
and beef treated immediately after flushing had poor color.
Of the beef receiving 0.25% carbon monoxide treatments, beef
treated one hour after flushing had ~air color; beef treated
15 minutes and beef treated immedaitely after flushing had poor
color. ~11 beef samples receiving 0.1~ treatment had poor color,
regardless of the time elapsed after nitrogen flushing. In
no case did the penetration of carboxymyoglobin into the meat
exceed about 0.25 inch.
None of the beef was biologically spoiled, but air
contxol samples maintained at the same temperature over the
same storage period were all badly spoiied.
This example demonstrates that a 1% carbon monoxide
concentration is ef~ective to establish and maintain good
red beef color for extended storage periods regardless of the
time lapse between conversion of oxymyoglobin to reduced
myoglobin through inert gas flushing and the subsequent conversion
of reduced myoglobin to carboxymyoglobin. Carbon monoxide
concentrations lower than 1% may be effective wh~re sufficient
time is allowed after inert gas 1ushing to effect conversion
` o oxymyoglob~n to reduced myoglobin on the bee surace.
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EXAMP~E V
Each of six beef ribsteaks was placed in a separate
10-liter desiccator, and each desiccator was then flushed with
nitrogen to reduce the oxygen content to about zero percent. The
steaks were left in this atmosphere for about one hour, after
which the meat had turned from red to purple in color, indicating
that oxymyoglobin on the beef surface had changed to reduced
myoglobin. Carbon dioxide was then fed to each desiccator
until the concentration in each had reached about ~0% by volume.
Then carbon monoxide was added at concentrations of 100 (1%),
7S (0.75%), 50 (0.5~ 5 (0.25%~,15 (0.15%) and 10 (0.1%) cc to
the si~ different desiccators, and each was held in this
condition at 3~F. for a period of nine days.
At the end of this period, all beefsteaks maintained
under the atmosphere containing 1%, 0.75%, 0.5% and 0.25% carbon
monoxide maintained the good red color of carboxymyoglobin.
Beef held under the other atmospheres had good color, but was
significantly less attractive. None of the treatments produced
a penetration below the surface of the beef of greater than
about 0.25 inch, and none of the meat was spoiled at the end
of the storage perio~. These results indicate that the concen-
tration of carbon monoxide may be as low as about 0.25% by
volume where the conversion of oxymyoylobin to reduced myoglobin
is complete before conversion to carboxymyoglobin is effected.
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EX~M~LE VI
Separate, 100 gram chunks of beef, pork and lamb
were placed into 12 different 10~1iter desiccators. Nitrogen
was fed to each desiccator until the nitrogen concentration
in each rose to nearly 100%. Carbon dioxide was then fed
to each desiccator until the concentration o~ carbon dioxide
in each desiccator reached about ~0~. Immediately
thereafter, carbon monoxide was fed to three of the desiccators
until the concentration therein reached about ]%, about 0.5~
and about 0.25% respectively. Fifteen minutes later, the same
concentrations of carbon monoxide were fed to three other
desiccators. Thirty minutes later, the same three concentrations
were fed to three more desiccators. Finally, one hour after
the carbon dioxide content of each desiccator was raised to
80%, the carbon monoxide was fed to the last three desiccators,
raising their carbon monoxide content to abou-t 1%, about 0.5%,
and about 0.25%, respectively. All desiccators were held
under these conditions for 15 days at a temperature of about 33-
34F.
Observation of the meat immediately after nitrogen
flushing revealed that the red oxymyoglobin on the surface of
the meat had been changed to the purple color of reduced myoglobin.
In all cases where the carbon monoxide content was raised to about
1~, all of the meat changed from the purple myoglobin color
to the red color of carboxymyoglobin within two days. However,
in this test, where the concentration of carbon monoxide was 0.5
or 0.25~, good red carboxymyoglobin did not form on the surface
of the beef, but did form on the surface of the lamb or pork.
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In all cases, none of the meat spoiled during the 15-day
storage period, and none exhibited a carboxymyogl~bin penetration
below the surface of the meat greater than about 0.25 inch.
These results show that lower concentrations of carbon
monoxide may be used to convert reduced myoglobin on the surface
of pork and lamb than to effec~ the same conversion on the sur-
face o~ an equal amount of beef.
EX~LE VII
:
Into each of three 10-liter desiccators were placed
one pound samples of fresh, ~round chuck beef hamburger. Each
test sample of hamburger was bricJht red in color. Using a
nitrogen flush, the oxygen content of each desiccator was
reduced to about 2-3~. A similar procedure was applied to two
one-pound samples of fillet of sole in two o-ther desiccators.
One hour after the oxygen content of the five
desiccators was reduced to about 2-3~, the color of the hamburger
had changed from bright red to reddish-purple. The color of
the fish had not noticeably changed.
After observing the color change in the hamburger,
100 cubic centimeters (1% by volume) of carbon monoxide was
added to each of the five desiccators (3 containing hamburger
samples, 2 containing fillet of sole samples). ~11 the desiccators,
and five control samples (3 hamburger samples, 1 pound each,
and 2 fillet o~ sole samples, 1 pound each, neither subjected
to nitrogen flush or carbon monoxide) were placed in a room
at 35F. and held for 16 to 18 hours. Thereafter, the samples
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were removed from the desiccators, and, together with control
samples, were placed in a freezer at a temperature of about
0 to about SF. for ten days.
After the ten day storage period in the freezer,
all samples were removed and allowed to thaw at ambient
temperature or 6 hours. The carbon monoxide-treated hamburger
had an attractive red color com~arable to fresh hamburger.
The treated fillet of sole had a pink color closely approximating
the color of fresh fish. The two untreated control fillet of
sole samples had a tannish-white appearance, and were considerably
less attractive than the treated fish. The three untreated
hambur~er control samples were mostly brown in color and quite
unattractive.
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