Color-stabilized semi-moist food and process

A semi-moist food containing an animal protein source is color stabilized by reacting carbon monoxide with the animal protein source, to provide a satisfactory color.

BACKGROUND OF THE INVENTION 
This invention relates to a food product and more particularly to a 
semi-moist food product containing color stabilized animal protein which 
food product is suitable for either human or pet consumption. 
Within the class of pet foods, there are three general subdivisions -- dry 
pet food, moist pet food, and semi-moist pet food. Stability after the pet 
food package is opened is critical. Dry pet food tends to be the most 
stable pet food with the least sophisticated packaging required to 
maintain that stability. Customarily, dry pet food is not as palatable as 
the other types of pet food. Semi-moist pet food tends to be a relatively 
stable pet food requiring somewhat more stringent packaging conditions 
than dry pet food, but with a corresponding increase in palatability. 
Moist pet food tends to be the most palatable of the three classes of pet 
food, but requires the most stringent packaging conditions. However, moist 
pet food is still the most acceptable to pet owners and pets. 
It is generally accepted that any member of the class of pet foods must 
please the owner of the pet, and the pet. The owner is pleased by a pet 
food which has an appearance close to that of meat. The pet is pleased by 
a pet food which has an acceptable taste, odor, and other features. 
Inherent in a meatlike appearance, is a red coloration. One means of 
achieving a red coloration in a pet food containing meat, or blood is the 
use of a salt such as sodium nitrite. When present in an aqueous 
environment, the nitrate ion is in equilibrium with nitrous acid and 
nitric oxide. The nitric oxide potentially reacts with either the meat 
protein, myoglobin, or the blood protein, hemoglobin. The specific locus 
of the combination between such proteins and nitric oxide is believed to 
be the iron molecule which is permanently present as a reactive site 
normally reserved for the binding of oxygen. The above proteins carry out 
the physiological purpose of oxygen transfer to the body. When the binding 
between the nitric oxide and the protein occurs in combination with heat 
sufficient to denature or precipitate the protein, a heat-stable, 
acetone-extractable, red pigment is established. This pigment accounts for 
the acceptable color in many pet foods. The basic problem with the use of 
the nitrite to achieve the desired color is the fact that it has 
undesirable characteristics when consumed. It may be a carcinogen or react 
to form a carcinogen. These undesirable characteristics render it 
necessary to find a replacement for the nitrite ion which will achieve the 
desired color results without having an adverse effect on the pet food. 
Further complicating the coloration for foods is the recent banning of dyes 
which have a long history of use in foods as colorants. This ban, imposed 
by governmental regulations, further limits the ability of food processors 
to achieve suitable coloration in the product. A great benefit to the 
industry may accrue if the coloration problem for the foods can be solved 
in an acceptable fashion. 
Another basic problem with color-stabilizing the above-referenced meat 
proteins is that the complex formed is more stable when the iron in the 
protein is in the (Fe II) state. However, it is difficult to maintain that 
state. The (Fe III) state is more stable. Therefore, the iron content 
tends to oxidize to the (Fe III) state before the stabilization effect 
takes place. It is, therefore, desirable to stabilize the above-referenced 
proteins while maintaining the iron content thereof in the (Fe II) state. 
Color is also important for a semi-moist pet food. Semi-moist pet food 
provides a meat-like appearance to which color greatly contributes and has 
a moisture content generally ranging from about 15 percent to about 50 
percent. Since semi-moist pet foods are higher in moisture content than 
dry and lower in moisture than canned, special techniques are required to 
render it microbiologically stable. This moisture content in combination 
with special techniques may produce a microbiologically stable food which 
does not require refrigeration. At the same time, the higher moisture 
content of the semi-moist pet food provides an increased palatability when 
compared to the dry pet food. The semi-moist pet food is generally 
rendered microbiologically stable by using high levels of sugar and 
solutes, or other suitable means. In this fashion, shelf stability without 
refrigeration is achieved while providing a food having increased 
palatability relative to dry pet food. If a stable color can be provided 
for these semi-moist foods, color may be added to the listed advantages 
thereof. 
The stabilization of color in food products is a problem in the art -- 
especially in semi-moist pet foods -- in view of the recent government 
bans on food dyes. Yet the final product appearance aspect renders color 
stabilization important to semi-moist pet foods. 
THE INVENTION 
Therefore, it is an object of this invention to provide an improved 
semi-moist food having a color acceptable to the consumer. 
It is a further object of this invention to provide a stabilized red 
coloring for use in a semi-moist food. 
It is a still further object of this invention to provide a replacement for 
the banned coloring in semi-moist foods. 
Also, an object of this invention is to provide a process for color 
stabilizing a food. 
Another object of this invention is to provide a process which color 
stabilizes a food without the use of banned coloring agents. 
These and other objects of this invention are met by providing a process 
for reacting an animal protein source with carbon monoxide to form a color 
stabilized protein source and incorporating the color stabilized protein 
in a semi-moist food, to thereby provide a color-stabilized semi-moist 
food. This feature is especially applicable to semi-moist pet foods. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An animal protein source, treated with carbon monoxide to stabilize the 
color thereof, is incorporated into a semi-moist food to form a 
color-stabilized food and more particularly, a color-stabilized semi-moist 
pet food. 
Several important variables determine the amount of color stabilization in 
pet foods formed by the process of this invention. The color stabilization 
is achieved for the purposes of this invention by treating blood or meat 
with carbon monoxide. The variables which affect the color obtained 
include (1) the extent of saturation of potential carbon monoxide bonding 
sites, (2) the oxidation state of the iron in the protein of the meat or 
blood, (3) the final concentration of blood or meat protein in the total 
pet food formulation, and (4) the type of heat (dry or moist) and its 
application process which stabilizes the color of the carbon monoxide 
treated material. Color stabilization of the animal protein used in a 
canned pet food is more thoroughly described in copending U.S. Patent 
Application No. 626,285 filed Oct. 28, 1975, which matured into U.S. Pat. 
No. 4,001,446 to Larry Lee Hood, this patent being incorporated herein by 
reference. This application expands the concept of the Hood patent to 
semi-moist foods. 
The protein source which is more thoroughly or completely saturated has a 
color much brighter than a protein source which is less saturated. The 
protein suitable for reaction with carbon monoxide is an animal derived 
protein source containing hemoglobin, myoglobin, or mixtures thereof. 
Bonding between the iron and the carbon monoxide is more efficient if the 
iron is in the (Fe II) state. Within the total pet food formulation, the 
color is affected by the concentration of the treated and untreated blood 
or meat protein in the pet food. As moistness of the meat increases, the 
reaction of the carbon monoxide with the protein increases, and becomes 
more complete. 
In the preferred process for forming the color stabilized animal protein 
for use in the semi-moist pet food, an aqueous suspension or dispersion or 
slurry containing appropriate proteins is treated with carbon monoxide to 
form a bright red, heat stable color. Basically, the protein is an animal 
protein. The protein is blood or meat, or mixtures thereof. By blood is 
meant the blood remaining and drained from a slaughtered animal. By meat 
is meant the flesh of cattle, swine, sheep, goats, horses, whale, and 
other mammals, in addition to poultry and fish. Also suitable as a meat 
component of this invention is a meat by-product. By meat by-product is 
meant those items shown in the 1976 Association of American Feed Control 
Officials, Inc. under No. 9 Animal Products, page 77 and following which 
says meat by-products are the non-rendered, clean, wholesome parts other 
than meat derived from slaughtered animals. Meat by-products include but 
are not limited to lungs, spleen, kidneys, brains, livers, and 
partially-defatted, low temperature, fatty tissue -- provided these 
material contain sufficient hemoglobin or myoglobin for reaction with 
carbon monoxide. If it bears a name description of its kind, it must 
correspond thereto (Proposed 1973, Adopted 1974, NRC5-00-395). 
Meat or meat by-products may be used in the invention in any reasonable 
size particle. In fact, chunks formed by merely cutting the meat or meat 
by-products are suitable for use in this process. However, if the meat or 
meat by-products are ground to a point where they are fine enough to be 
suspended in an aqueous slurry, the reaction is more efficient and is 
carried out to a greater extent. For example, the meat may be ground to a 
size of up to 1/2 inch (1 centimeter) particles. More specifically, the 
meat may be ground to a size of about 1/64 inch (0.03 centimeter) to about 
1/4 inch (0.6 centimeter) particle. Most specifically the meat or meat 
by-products may be ground to a size of about 1/8 inch (0.15 centimeter) to 
1/8 inch (0.3 centimeter) particle. 
The slurry is formed in any suitable fashion. Blood which has a substantial 
amount of liquid already present therein requires less water to form the 
slurry than does meat or meat by-products. The higher the solids content, 
the longer the reaction takes. However, any amount of solids is suitable 
for use. The total water content of the slurry includes both added water 
and water inherently in the meat or meat by-products to be treated. 
Generally however, the slurry may have up to about 50 percent by weight 
solids content. More specifically, the slurry may have about 0.1 to about 
45 percent by weight solids content. Most specifically, about 5 to about 
30 percent by weight solids content is suitable for the slurry. These 
figures are easily adjusted by a person having ordinary skill in the art 
to achieve the desired slurrying factors. By "up to" here and throughout 
the specification is meant that at least a trace of the named component is 
present at the lower limit. 
The slurry is then contacted with carbon monoxide. The contact with carbon 
monoxide is continued until at least 10 percent of the possible carbon 
monoxide reaction points are saturated. More preferably, the saturation 
with carbon monoxide ranges at least about 50 percent. Most preferably the 
saturation with carbon monoxide ranges at least about 75 percent. The 
theoretical aspects of saturation are not usually completely achieved. 
Practically the maximum saturation is obtained at about 80 percent of the 
theoretical. However, up to and including 100 percent saturation is also 
possible. The cited saturation points percentages are all based on the 
theoretical percentage. 
The saturation percentage is adjustable to achieve a desired color. 
Optionally however, the blood can be thoroughly and completely saturated, 
that is, up to the maximum theoretical standpoint. Color is then 
adjustable by using untreated material to adjust the color downward or 
make it less dark. 
Optionally minor adjustments in the color of the treated blood or meat can 
be made by adding colors such as iron oxide, generally having the formula 
of Fe.sub.3 O.sub.4, the Fe.sub.3 O.sub.4 generally being a description of 
a mixture of Fe.sub.2 0.sub.3 and FeO. Also FD&C food colors such as a 
Brown mixture, an Orange mixture, or Red may be used for minor color 
adjustments. These color adjustments can be used individually or in any 
reasonable combination and are minor in comparison to the carbon monoxide 
treated protein. For example, both the food coloring and the untreated 
blood may be mixed to achieve the desired functionality or color. In this 
fashion there are a variety of means of achieving the desired color. 
Incorporation of the iron oxide or other materials is 0 to about 0.5 
percent by weight of the protein source. More preferably about 0.1 percent 
by weight of the protein source comprises the coloring. 
The slurry thus formed with the protein source and the various dyes is 
treated in any reasonable temperature. Customarily more efficient gas 
reaction with the carbon monoxide is achieved at either room temperature 
or slightly below. It is feasible to heat or cool the slurry for the 
reaction. However, at the present time the process economics of heating or 
cooling do not compensate therefor. 
One effective way of determining the amount of saturation is to observe the 
color of the product. This color is determined either visually or by 
comparison of a standard scale such as that disclosed on the Agtron scale, 
the Colormaster (Adams) scale, or the Munsell color chart. The stabilized 
blood or protein generally has an Agtron rating of at least 20 percent. 
The "L" rating for stabilized blood or protein of this invention on the 
Colormaster about 25 or higher; the "a" rating 55 or higher; and the "b" 
rating is generally insignificant due to it being a yellowness 
measurement. Improved red for the stabilized protein is also shown on the 
Munsell color scale. 
It is also feasible to measure the flow rate to determine the amount of 
carbon monoxide gas used in the reaction. Standard simple calculations are 
used to determine the amount of carbon monoxide necessary to react with 
the protein source. When it is desired to form a completely saturated 
protein source having all carbon monoxide reaction sites saturated, the 
carbon monoxide may be used in excess to assure the complete reaction. 
Again the standard calculations are permitted to determine exactly what 
source and amount of carbon monoxide are usable. For example, typical 
methods for determining carbon monoxide concentration include the Van 
Sylke manometric determination which is a standard clinical chemistry 
method, or the Conway micro diffusion cell method using palladium chloride 
with a back titration of the liberated hydrochloric acid. Other known 
methods are also suitable for this purpose of determining the carbon 
monoxide saturation of the protein source. 
The most effective way of binding carbon monoxide to the protein source is 
to have the iron content of the protein be in the (Fe II) state. 
Frequently, however, the iron in the protein oxidizes to the (Fe III) 
state. In this state, binding of the carbon monoxide is not efficient and 
a proper red color is not achieved. In order to avoid the oxidation to the 
(Fe III) state, at least two options are possible. For the first option, 
the protein source may be used quickly enough to prevent such oxidation. 
For a second option, an edible reducing agent is incorporated into the 
protein in an amount sufficient to reduce most of the iron to the (Fe II) 
state. Too much reducing agent may adversely affect other food components 
-- such as vitamins. Typical edible reducing substances may be used singly 
or in combination. Satisfactory examples of edible reducing substances 
include ascorbic acid and salts thereof, sulfur dioxide, or sodium 
bisulfite. Other suitable edible reducing substances include erythorbic 
acids and salts thereof. A suitable salt is sodium erythorbate or sodium 
ascorbate. Generally speaking, these reducing agents are used in an amount 
of 0 to about 2 percent by weight of the protein source. More preferably, 
the amount of the reducing agent is a trace amount to provide the 
reduction of (Fe III) to (Fe II) to about 1 percent. Most preferably, the 
amount of reducing agent is a trace amount to about 0.2 percent. The use 
of these reducing agents permits the storage of the protein source until 
use as desired in the color stabilization process, and, even if the 
protein is used immediately, guarantees the (Fe II) state of the iron. 
Other options may also prevent the oxidation of the iron. 
Besides reducing the iron in the protein source to the (Fe II) state, 
further process limitations assist the completion of the reaction. 
Preferably, the content of the carbon monoxide is increased by agitating 
the aqueous suspension while contact is made between the suspension and 
the carbon monoxide. One way to promote an efficient combination between 
carbon monoxide and the protein source is to agitate these materials 
together in a sealable (gas tight or oxygen impermeable) vessel. The 
guiding principle is the controlled saturation of carbon monoxide binding 
in the heme proteins. How this is accomplished is obvious to one skilled 
in the art of processing such mixtures. One possible way to accomplish 
this process is to proceed as follows: Firstly, animal protein slurry is 
placed in an air tight vessel. Secondly, carbon monoxide is admitted to 
purge the vessle of air. Then, the vessel is sealed and agitated with a 
shaking or oscillatory motion, or slow rolling action. These variables are 
manipulatable to obtain various shades of red in the product. Generally, 
reaction times range from about 0.5 minutes to about 80 minutes. More 
preferably, the reaction time is from about 1.0 to 60 minutes. The time 
may vary due to attainment of different agitator rates, state of heme 
protein, temperature or other process conditions, which, a person having 
ordinary skill in the art may determine in view of the disclosure in this 
application. 
Agitation can be done in any suitable equipment that utilizes efficient 
method of gaseous transfer across water slurry film. Typical agitation 
includes a wrist shaker, or other manipulation of the protein source. 
Suitable agitation produced by rotation of the reacting vessel ranges from 
about 5 to about 45 rpm. More preferably, the rotation agitation ranges go 
from about 20 to 25. Most preferably, the suitable shaking agitation range 
goes from about 170-190 cycles per minute. 
The treated proteins used in the semi-moist pet food of this invention are 
highly stable. The color is not apparently extractable with acetone as is 
the case with the nitrite hemoglobin complex. Stability of the carbon 
monoxide complex with the hemoglobin or myoglobin is further indicated by 
only slight solubilization in ammonium hydroxide. This reaction of the 
carbon monoxide has the further effect of stabilizing and having no 
adverse effect on the protein is indicated by the fact that the gel 
electrophoresis patterns are not altered by the carbon monoxide treatment 
of the protein. 
If it is not desired to use the carbon monoxide treated protein 
immediately, frozen storage is the most stable means of retaining the 
product for future use. Refrigeration storage is acceptable, but use must 
be made more quickly in order to avoid the microbial deterioration. 
Following preparation of the slurry and the color-stabilized protein, other 
ingredients, such as a water soluble solutes, vegetable protein, animal 
protein containing hemoglobin or myoglobin, or animal protein containing 
substantially no hemoglobin or myoglobin, are added to the color 
stabilized protein and mixed therewith to achieve a "dough" typical of 
semi-moist products. Mixing is preferably, but not necessarily 
accomplished in dark conditions and avoids unnecessary heating of the 
dough. A mixing temperature near or slightly below room temperature is 
preferred. The dough is extruded in a fashion considered normal for this 
type of product, and a product color is achieved which reflects the 
addition of carboxy derivatives of heme proteins. 
The technology of semi-moist pet foods is well known and is the subject of 
prior U.S. Pats., exemplified by Bone, No. 3,380,832; Burgess, No. 
3,202,514; and Burkwall, No. 3,974,296; incorporated herein by reference. 
In general, semi-moist, meat-like pet food is designed to resemble freshly 
ground meat, or marbled meat chunks. The use of carboxyhemoglobin or 
carboxymyoglobin imparts the red, meaty appearance to the semi-moist 
product. The requirement of using various synthetic dyes which, according 
to the Food and Drug Administration, possess questionable toxicological 
properties is thus avoided. Furthermore, because of the controllable 
nature of color development in the carboxyhemoglobinmyoglobin process, it 
is now possible to produce color variation ranging from brownish-purple 
(liverlike) to pinkish-red (fresh meat) in a semi-moist pet food. 
Color change can occur when the carbon monoxide treated protein is being 
used in a semi-moist pet food. It is possible to vary the final shade of 
red from bright red to one of more brown character by heating the product 
to temperatures of about 70.degree.-80.degree. C. in an open condition 
prior to packaging the pet food. Such heat induced color loss is less 
drastic if the protein is treated with reducing agent or if the heating is 
conducted in a closed container, to thereby provide moist heat conditions. 
In semi-moist products, product heating is accomplished during extrusion. 
Maximum color of a semi-moist product carbon monoxide treated animal 
protein source is achieved when this product exits the at 65.degree. C. to 
80.degree. C. by adjusting extruder jacket temperatures properly. As is 
well-known in the art, extruders have various zones -- each zone capable 
of being maintained at a different temperature. It is therefore possible 
to cool the last zone the product is in prior to emergence from the 
extruder to thereby cool the product to the desired temperature. Such 
temperatures are sufficient to pasteurize the product without degradation 
of color. Higher extrusion temperature may be utilized to satisfy the 
continuity in the manufacture of certain semi-moist product. Generally 
however, higher extrusion emergence temperature (above about 120.degree. 
C.) produces a less than maximum color yield. 
Extrusion of semimoist products may be done in a closed heating system 
(85.degree.-120.degree. C.) to provide heat conditions although the 
product emerges at a temperature in that range. This emergence of the 
product at such a high temperature constitutes open heating ofthe product 
which adversely affects the color. Another way to achieve a suitable 
product is achieved by using a cooling coil or tube for adjusting the 
temperature of emergent product back to 70.degree.-80.degree. F. 
(20.degree.-30.degree. C.). In other words the extruded dough is extruded 
directly into a zone having a temperature of 20.degree. C. to 30.degree. 
C. to thereby quickly cool the product. Although such a precaution is not 
absolutely required for utilization of this color system, it insures 
maximum retention of the red component associated with a particular level 
of carboxy derivative. 
An alternative method of product preparation which avoids open heating of 
carbon monoxide treated protein includes the following steps. Bovine blood 
and/or by-products are saturated to 100% theoretical with CO and mixed 
with propylene glycol. Other ingredients are assembled, mixed and heated 
to 80.degree. C. to 100.degree. C. to promote gelatinization of starch and 
cooking of meats. This mixture is cooled to room temperature, mixed with 
the carbon-monoxide treated blood and/or by-products and extruded at room 
(20.degree. C. to 30.degree. C.) temperature. 
A typical semi-moist pet food has about 3 percent to about 65 percent of at 
least one protein source therein. The protein source may be all animal 
protein which contains heme or myoglobin, or mixtures thereof with 
vegetable protein, meat meals or other animal protein, the other animal 
protein being free of myoglobin or hemoglobin. Part or all of the 
hemoglobin or myoglobin may be saturated with CO. The meat or meat 
by-products present in the semi-moist pet food are generally present 
within the range of about 3 percent to about 65 percent by weight of the 
semi-moist pet food. More preferably, the meat is present within the range 
of about 5 percent to about 40 percent by weight of the semi-moist pet 
food. Most preferably the meat is present in an amount in the range of 
about 10 percent to about 35 percent by weight of the semi-moist pet food. 
The pet food optionally also contains at least one vegetable protein from 
sources such as soy, cottonseed, peanut or other suitable vegetable 
protein. Within the semi-moist pet food, the vegetable protein is present 
in a total amount of about 0 to 65 percent, and more preferably about 5 
percent to about 50 percent. Most preferred, however, is 10 percent to 45 
percent by weight vegetable protein. Protein for the pet food is provided 
by vegetable protein, animal protein (including meat, meat by-products and 
meat meals), or mixtures thereof. 
A bacteriological and microbiological inhibitor system suitable for use in 
this semi-moist pet food is generally a two or more component stabilizer 
comprising at least one polyhydric component, a sugar source, and at least 
one antimycotic. Generally speaking, the polyhydric alcohol component or 
alcohol is present in amounts sufficient to provide semi-moist stability 
alone or in the presence of sugar. The polyhydric alcohol and the sugar 
source are defined in the semi-moist patents cited herein and are present 
in amounts sufficient to provide semi-moist stability. 
The antimycotic is generally present in an amount sufficient to prevent 
mold on a semi-moist pet food. More specifically, it is present up to 
about 0.5 percent by weight of the semi-moist pet food. More preferably 
0.01 percent to 0.3 percent antimycotic is used. A suitable antimycotic 
includes potassium sorbate, sorbic acid, calcium propionate, and methyl 
and propyl paraben. The preferred antimycotic is potassium sorbate. 
An edible acid or acid salt may optionally be present as a part of the 
microbiological and bacteriological inhibitor system to provide a neutral 
or slightly acidic food having a pH of from 4.5 to 7.5 in an amount 0 to 
about 3 percent by weight of the semi-moist pet food. More preferably 0.1 
percent acid to 2.5 percent acid is used. A suitable edible acid includes 
acids such as fumaric acid, hydrochloric acid, citric acid and acetic 
acid. However, phosphoric acid is preferred because of phosphorus content, 
availability, and other desirable features. These acids or salts thereof 
(for example sodium or calcium salts) are compatible with the carbon 
monoxide, color-stabilized protein. 
Other additives present in the semi-moist composition optionally include, 
but are not limited to, a vitamin mix and a mineral mix. The mineral mix 
and the vitamin mix are added for nutritional purposes. A further additive 
to the pet food may be at least one salt added for purposes of taste, 
nutrition, or a combination of purposes which are well known in the art. 
Typical salts include sodium choloride (table salt -- either iodized or 
uniodized), and potassium chloride. These additives are present in a 
sufficient amount to improve taste and nutrition if required and may total 
up to 10 percent by weight of the pet food. More preferably, these 
additives may total 0.25 percent to 5.0 percent. 
Other additives are disclosed in U.S. Pat. Nos. 3,380,832 to Bone, and 
3,765,902 to Charter, both patents being incorporated herein by reference. 
Additionally the patents illustrate semi-moist pet foods modifiable by 
this invention. 
An especially suitable product of this invention is in the semi-moist 
category of pet foods. The moisture content ranges from about 15 percent 
to about 50 percent by weight of the product. More preferably the moisture 
content is 18 percent to 45 percent. Most preferably the moisture content 
is 20 percent to 40 percent. By moisture content is meant the water 
content of the semi-moist pet food whether the water is present as free 
water, part of at least one other pet food component, or combinations 
thereof. 
Packaging of the resulting product can be accomplished in any suitable 
fashion. Either air permeable or air impermeable films may be used. The 
films may be transparent, translucent, or opaque and made of any suitable 
material. Typical packaging materials include polyethylene film. The 
packages may be flexible or rigid, a pouch or a can. It is especially 
desirable that the package include as at least one layer thereof an oxygen 
impermeable film or coating. Typically oxygen impermeability is achieved 
by using a polyethylene terephthalate film or coating. Also an oxygen 
scavenger may be incorporated in the package to remove residual oxygen in 
the package or to remove oxygen from air entering the package if the 
package is not air impermeable. A typical oxygen scavenger is glucose 
oxidase. The further packaging requirements for this product are well 
within the skill of the packaging technologist.

The following examples are intended to illustrate, without unduly limiting 
the invention. All parts and percentages are by weight unless otherwise 
specified. 
EXAMPLE 1 
Beef lungs (approximately 75 percent moisture and 25 percent solids) are 
ground through a 1/8 inch plate and then emulsified to form a slurry which 
is placed in a sealable container having a volume 8 to 10 times greater 
than the liquid volume. The container is rendered gas tight by a closure 
fitted with two gas valves, one suitable for the admission of gases, the 
other for exit of air and reaction gas. The container, now referred to as 
a reaction vessel is purged with a volume of carbon monoxide equal to four 
times the vacant space of the reaction vessel. The vessel is completely 
sealed, having insured that the vacant space above the blood is totally 
occupied with carbon monoxide and the vessel is agitated at 180 cycles per 
minute. Such agitation constantly coats the reaction walls with a thin 
film of the slurry and thereby guarantees complete reaction of carbon 
monoxide with the myoglobin binding sites after thirty minutes. This 
example is substantially Example 4 of the referenced Hood Patent and shows 
formation of a carbon monoxide treated protein to thereby stabilize the 
color. 
EXAMPLE 2 
U.S. Pat. No. 3,974,296 to Burkwall discloses a simulated meat comprised 
of: 25 parts by weight beef tripe; 25 parts by weight sucrose; 16 parts by 
weight soy grits; 16 parts by weight soy flour; 9.7 parts by weight beef 
intestines; 4 parts by weight propylene glycol, 0.3 parts by weight 
potassium sorbate; 4 parts by weight salt, vitamins, and minerals; 
sufficient food coloring to provide a red meat-like color and sufficient 
water to bring the moisture content to about 25 percent by weight. This 
mixture is then heated to about 85.degree. C. and extruded into small 
strands forming an acceptable simulated meat product. This product is a 
standard red simulated meat product known in the art. 
EXAMPLE 3 
The process of Example 2 is repeated replacing an equivalent amount of beef 
tripe with 25 parts by weight beef lungs and eliminating red food coloring 
to form a control product having a brownish, greyish color. Beef tripe 
appears to be white and contains no hemoglobin or myoglobin. 
Secondly, the process of Example 2 is repeated again, but this time 25 
parts by weight replacing the beef tripe with an equivalent portion of the 
beef lung reaction product of Example 1 to provide a formula B. By 
examination according to the procedure of the Hood patent, the color of 
Formula B containing the carbon monoxide treated beef lungs is superior to 
Formula A which contains untreated beef lungs. The red color of Formula B 
is also comparable to the red color of the food dye-containing product of 
Example 2. 
EXAMPLE 4 
The procedure of Example 2 is repeated with the following exception. An 
equivalent amount of beef tripe is replaced with five parts by weight of 
carbon monoxide treated blood and the red food coloring is omitted. The 
color of this product is superior to the color of Example 2. The carbon 
monoxide treated blood is formed in a manner similar to that of Example 1 
of the instant application and Example 1 of the Hood patent. 
EXAMPLE 5 
The pet food of Example 1 of U.S. Pat. No. 3,380,832 to Bone (incorporated 
herein by reference) is formulated using a base of red and marble (Control 
A). The Bone Example 1 is repeated replacing the beef trimmings in the 
base red with 100 percent carbon monoxide saturated beef trimmings and 
eliminating all other dyes in the base to make Formula B in accordance 
with this invention. The pet food (Formula B) containing the carbon 
monoxide saturated beef trimmings is superior in color and nutrition to 
the pet food of Example 1 in Bone. However, it is necessary to cool the 
emerging product to 25.degree. C. by extruding directly into a 
refrigerated zone at a temperature of 25.degree. C. to avoid raising the 
air temperature. 
Example 1 of Bone is repeated eliminating all dyes in the base to provide 
Formula C, which is inferior in color to Formulas A and B. 
EXAMPLE 6 
A sample of Formula B of this invention as set forth in Example 5 is 
divided into a first part and a second part. The first part is packaged in 
a transparent, air impermeable film. The second part is packaged in a 
transparent air permeable film. The packages are stored at 20.degree. C. 
and relative humidity 50 percent for two months. The color of the packaged 
first part deteriorates more than the color of the packaged second part -- 
thereby indicating the air impermeable film to be a more desirable 
packaging film than the air permeable film.