PALATABILITY ENHANCERS FOR PET FOOD AND METHODS OF MANUFACTURE
BACKGROUND OF THE INVENTION
[0001 ] This invention is directed to a palatability enhancer for pet food and a method of its
manufacture. Particularly, this invention relates to a palatability enhancer providing a savory
flavor such as meat. More particularly, this invention relates to a process for improving the
palatability of pet foods of either low or high moisture content by enhancing the flavor to
increase its acceptability to cats and dogs.
[0002] It should be understood that the expression "dry pet food" as used herein includes
foods having a low moisture content. For example, dry pet food may contain less than about
20% moisture so that the free water content is generally not sufficient to support the growth
of microorganisms. High moisture content pet food is intended to include the semi-moist and
canned types of foods. The invention is applicable to all types, but is particularly significant
with dry foods which often are least appealing to domestic animals.
[0003] Advantages associated with dry pet foods are that they are generally more nutritious,
on an equal weight basis, require less expensive packaging, and are more convenient to use
than moist foods. However, domestic animals are often quite particular in their tastes and,
therefore, improving palatability significantly improves the deliverability of a dry food. To
improve taste, a variety of materials have been utilized to coat the surface and/or are mixed
with the dry constituents to enhance the flavor. For example, phosphoric acid has been
coated onto the surface of a dry cat food as a palatability enhancer. More specifically, U.S.
Pat. No. 3,679,429 discloses a method for improving palatability of dry cat food by coating
pellets of food with fat and palatability enhancing acids such as phosphoric or citric.
[0004] Palatability of dry pet foods may also be enhanced by the application of flavors. As
an example, flavors are described in U.S. Pat. No. 5,186,964 as meat and cheese flavorings.
[0005] However, the use of meat or cheese flavoring is not always easy to accomplish. One
complication in developing flavorants and palatability enhancers for pets is unpredictability.
Moreover, flavorants which work effective with humans do not often work as effectively with
pets. Similarly, a flavorant which is effective with one species may not work as well with a
different animal group. Furthermore, pets are unable to express their preferences in an
effective manner. Accordingly, palatability testing must be employed.

[0006] One primary area of focus has been to provide pet foods with a savory meat flavor.
In fact, this effort exists simultaneously with respect to flavoring human foods. In animals,
this has typically been accomplished using poultry viscera, heart and liver digests. However,
this flavorant system is somewhat undesirable because it cannot meet with the increasing
demand for palatability of pet foods, especially dry pet foods.
[0007] In humans, artificial meat flavorants have been investigated as demonstrated in U.S.
Pat. No. 5,039,543 wherein it is disclosed that phospholipids, create a desirable meat aroma.
Specifically, a flavorant stated to have a savory meat aroma and flavor is comprised of a
phospholipid of animal origin and a sulfur containing compound which is reactive with the
phospholipid. Similarly, in U.S. Pat. No. 4,045,587, herein incorporated by reference, a meat
flavorant comprised generally of a cyclic carbonyl compound is disclosed. Further discussion
of artificial meat flavors is provided in U.S. Pat. No. 3.892,878, herein incorporated by
reference, wherein it is stated that certain alkane thiols and alkane mercapto sulfides alter the
flavor of foodstuff to provide a roasted meat taste for humans.
[0008] Interestingly, notwithstanding the alleged success of these various artificial meat
flavors, many human foods still rely on a combination of natural flavors and yeast.
Furthermore, there has been no successful development of an artificial meal flavorant which
has demonstrated success in meeting the particular and unique palatability demands of
domestic animals.
[0009] Therefore, it would be desirable in the art of animal feed, to have available a meat
flavorant which is easily storable, preservable and relatively inexpensive yet provides a
savory meat-type flavor.
SUMMARY OF THE INVENTION
[0010] This need is met by the present invention.
[0011] A method for producing a palatability enhancer for a companion animal food
product is presented. The method includes combining at least one aroma chemical selected
from 2-methylfuran, 2-methylpyrrole, 2-methyl-thiophene and dimethyl disulfide with an
animal or vegetarian digest composition. In one embodiment, the method further includes (a)
combining at least one reducing sugar with said at least one aroma chemicai and said digest

composition to form a mixture; and (b) heating the mixture to initiate a reaction process. In
another embodiment, the mixture further includes at least one reducing sugar is selected from
xylose, rhamnose, glucose, fructose, and ribose. An additional embodiment includes adding
at least one sulfur-containing compound selected from cysteine. cystine, glutathione.
methionine, thiamine, sodium sulfide, and ammonium sulfide lo the mixture.
[0012] In one embodiment, the aroma chemical is added to the mixture prior to or following
heating. In another embodiment, the mixture is heated to between about 60° and about 180°C.
In yet another embodiment, mixture is heated to between about 90 °C and about 130 °C. In
one embodiment, the mixture is heated for a period of about 1 minute to about 4 days. In
another embodiment, the reaction process is performed at a pH of between 2.5 and 10. In yet
another embodiment, the reaction process is performed at a pH of between 6 and 9.
[0013] In another embodiment, the method further includes applying the palatability
enhancer to a pork base, a chicken base, a vegetable base, a fish base, or a mixture thereof. In
a further embodiment, the animal digest composition includes viscera selected from pork
viscera, chicken viscera, and a combination thereof.
[0014] An additional embodiment further includes combining the palatability enhancer with
a basal composition containing organosulfite salts formed by contacting unsaturated fatty
acids that oxidize to form aldehydes or ketones in the basal composition with a source of
bisulfite anions.
[0015] In yet another embodiment, the method further includes extruding the palatability
enhancer with a basal composition to form a dry or semi-dry kibble. Another embodiment
includes applying the palatability enhancer to the surface of a kibble after the kibble is
extruded.
[0016] Also provided is a method for improving the palatability of a cooked moist
companion animal food product wherein the food product is contacted with the palatability
enhancer. In one embodiment, the palatability enhancer is conlacted with said food product
prior to cooking.
[0017] In another embodiment, the food product includes an additional palatability
enhancing composition. In yet another embodiment, the additional palatability enhancing
composition includes a palatability enhancing quantity of one or more compounds selected

from pyrophosphoric acid, polyphosphoric acid salts, phosphoric acid, phosphoric acid salts,
acid tripolyphosphate, tripolyphosphate salts, acid hexapolyphosphate, hexapolyphosphate
salts, citric acid, citric acid salts, tartaric acid, tartaric acid salts, fumaric acid, fumaric acid
salts, lactic acid, lactic acid salts, acetic acid, acetic acid salts, formic acid, formic acid salts,
hexamic acid and hexamic acid salts.
[0018] In one embodiment, the food product includes a food-grade raw meat or meat by-
product. In another embodiment, the meat or meat by-product is selected from meat and
meat by-products derived from beef, pork, sheep, lamb, poultry, duck. tuna, salmon, cod.
whitefish and shrimp.
[0019] In yet another embodiment, the food product includes an animal or vegetable fat or
oil.
[0020] In one embodiment, the method is a batch process. In another embodiment, the
method is a continuous process.
[0021] Also provided is an extruded companion animal food composition containing the
palatability enhancer. In another embodiment, a moist cooked companion animal food
composition containing the palatability enhancer is also provided.
[0022] Other features of the present invention will be pointed out in the following
description and claims, which disclose the principles of the present invention, and the best
modes which are presently contemplated for carrying them out.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG.l depicts the structures of representative aroma chemicals for use in the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is directed to a method for producing and the resultant palatability
enhancer, which provides an enhanced meaty flavor to dry or high moisture content animal
feed.

[0024] Due to the lack of direct feedback from animal test subjects, the prevailing
measurement of pet food flavor performance in the pet food industry is a two bowl, free
choice methodology based on individual animal feed intake ratio with a minimum of 20
animals (dogs or cats) per test for two day duration as described in Palatability Testing: Two-
Part Tests. Methods and Data Analysis Techniques; Griffin. R., September/October Pet Food
Industry. 1996. Moreover, the complexities associated with the food evaluation process can
be reduced by dealing fundamentally with the behavior of the animals. Specifically, it is
assumed that the greater the food intake, the more palatable the food is. Such an assumption
allows conclusions or inferences to be made about the animal's cognitive evaluation of the
food.
[0025] The present invention involves combining at least one aroma chemical with an
animal or vegetarian digest composition to generate a flavorant that can significantly improve
the palatability performance of pet foods. The aroma chemical and digest composition can be
further combined with at least one reducing sugar to form a mixture, which is then heated to
initiate a reaction process for producing the flavorant. The mixture may further contain at
least one sulfur-containing compound. The methods of the present invention are typically
carried out in a batch or a continuous process.
[0026] Further, the methods of the present invention are typically carried out at elevated
temperatures. The range of reaction temperatures is generally from about 60 to about 18O°C.
preferably about 90 °C to about 130 °C, under a pressure in the range of about 100 to about
280 Kpa. The reaction process is typically conducted at a pH between 2.5 and 10, preferably
at a pH between 6 and 9.
[0027] The reaction can take place over any suitable period of time, such as, for example, 1
minute to several days. Ten minutes to 5 hours is a typical reaction time. More specifically,
the time of the reaction is often more dependant on the amount of time it takes to heat up the
mixture to the desired final temperature and the time it takes to cool the reaction down
sufficiently to terminate reactive mechanisms. However, the reaction time is recognized to
impact on what reaction products are obtained.

[0028] The digest can be an animal digest or a vegetarian digest. Preferred animal digest
compositions contain viscera, such as offal from pigs, chickens, cattle, lamb, or fish.
Preferred viscera includes poultry heart. The animal digest composition may further contain
non-visceral tissues, such as liver.
[0029] Preferred sulfur-containing compounds include cysteine. cystine, glutathione.
methionine, thiamine, sodium sulfide, and ammonium sulfide. However, any sulfur-
containing compounds could be used in the process provided that the desired reaction
products are obtained. A typical amount of the sulfur-containing compound is from about 0.1
to about 10%, preferably from about 0.2 to about 2% by weight of the animal digest.
[0030] Suitable reducing sugars include xylose, rhamnose, glucose, fructose, and ribose. A
typical amount of the reducing sugar is from about 0.1 to aboul 20%, preferably from about 1
to about 10% by weight of the animal digest.
[0031] The method includes adding an aroma chemical selected from 2-methylfuran.
dimethyl disulfide, 2-methylthiophene, 2-methyl pyrrole or a combination thereof to the
animal digest composition prior to heating the composition. Alternatively, 2-methylfuran,
dimethyl disulfide, 2-methylthiophene. 2-methylpyrrole or a combination thereof may be
added to the composition after heating. When added, a typical amount of the aroma chemical
is from about 5 parts-per-billion (ppb) to about 500 parts-per-million (ppm), preferably from
about 20 ppb to about 300 ppm based upon the weight of the animal digest. A preferred
amount of 2-methylfuran is from aboul 2 to about J 000 ppm. A preferred amount of 2-
methylthiophene is from about 0.2 to about 1000 ppm. A preferred amount of dimethyl
disulfide is from about 0.2 to about 1000 ppm.
[0032] The palatability enhancers produced by the above-discussed methods can be used in
the produced form or can be blended with other ingredients to form a blended flavor. The
palatability enhancers may also be combined with an additional palatability enhancing
composition containing a palatability enhancing quantity of one or more compounds, such as
pyrophosphoric acid, polyphosphoric acid salts, phosphoric acid, phosphoric acid salts, acid
tripolyphosphate, tripolyphosphate salts, acid hexapolyphosphate. hexapolyphosphate salts.
citric acid, citric acid salts, tartaric acid, tartaric acid salts, fumaric acid, fumaric acid salts,
lactic acid, lactic acid salts, acetic acid, acetic acid salts, formic acid, formic acid salts.
hexamic acid or hexamic acid salts.

[0033] Methods according to the present invention also include adding the palatability
enhancer to a basal composition containing organosulfite salts, which were formed by
contacting unsaturated fatty acids that oxidize to form aldehydes or ketones in the basal
composition with a source of bisulfite anion.s. Methods for treating a basal composition to
form organosulfite salts are described in United States Patent Application Serial No.
60/692,035 filed on June 17. 2005, the disclosure of which is incorporated herein by
reference in its entirety.
[0034] The present invention also includes methods of preparing dry or semi-dry kibble and
moist cooked companion animal foods containing the palatability enhancer prepared as
disclosed above. Compositions containing the palatability enhancer, such as dry or semi-dry
kibble and moist cooked companion animal foods containing the palatability enhancer are
also provided.
[0035] As referred to within this description, dry and semi-dry companion animal foods
generally relate to a nutritionally balanced mixture of proteinaceous and farinaceous
materials having moisture contents of about 50% or less by weight. Moist companion animal
food products generally relate to a nutritionally balanced mixture of proteinaceous and
farinaceous materials having moisture contents above 50% by weight.
[0036] In moist food products, the proteinaceous and farinaceous materials are typically
formed into a solid mass with a hydrocolloid such as gelatin. The meat in rnoist food
products can be supplied by chunks of actual meat or by re-formed emulsified meat and meat
by-products. Moist companion animal food may also optionally include a gravy component
prepared from hydrocolloids and flavorings.

[0037] The companion animal food compositions described herein are not intended to he
limited to a specific listing of ingredients because such ingredients will depend on such
factors as, for example, the desired nutritional balance for the specific type of companion
animal, and availability of ingredients to the manufacturer. In addition to the proteinaceous
and farinaceous materials, the companion animal food composition may include vitamins,
minerals, and other additives such as flavorings, preservatives, emulsifiers and humectants.
The nutritional balance, including the relative proportions of vitamins, minerals, fat, protein
and carbohydrate, is determined according to dietary standards known in the veterinary art.
For example, the nutritional balance of a cat food composition is determined according to the
known dietary requirements for cats.
[0038] Suitable proteinaceous material may include any material having a protein content of
at least about 15% by weight including vegetable proteins such as soybean, cotton seed, and
peanut; animal proteins such as casein, albumin, and fresh animal tissue including fresh meat
tissue and fresh fish tissue; and dried or rendered meals such as fish meal, poultry meal, meat
meal, bone meal and the like. Other types of suitable proteinaceous materials include wheat
gluten or corn gluten, and microbial proteins such as yeast.
[0039] Suitable farinaceous material may comprise any material having a protein content of
less than about 15% by weight and containing a substantial proportion of starches or
carbohydrates, including grains such as corn, milo, alfalfa, wheat, barley, rice, soy hulls, and
other grains having low protein content. In addition to the proteinaceous and farinaceous
materials, other materials such as whey and other dairy by-products, as well as other
carbohydrates may be added, In addition, known flavorings including, for example, corn
syrup or molasses, may be added.
[0040] Generally, the term companion animal food product as used herein apply to
commercially sold, nutritionally balanced compositions that are intended to provide
substantially the sole diet for companion animals. Thus, such compositions may be described
as having minimum protein contents at which companion animal health is maintained.
However, the minimum protein content of the food varies according to the age and breeding
status for the animal.

[0041] For example, a nutritionally balanced cat food composition for breeding females and
kittens requires a minimum protein content of at least about 28% by weight on a dry matter
basis. A nutritionally balanced cat food composition for non-breeding and adult cats requires
a minimum protein content of about 26% by weight on a dry matter basis. More typically, the
protein content of commercially available cat food compositions for adult, non-breeding cats
is about 30% by weight on a dry matter basis, to insure that the food meets the nutritional
requirements of any cat.
[0042] Additionally, vitamins and minerals are added according to known American
Association of Feed Control Officials (AAFCO) guidelines. Such AAFCO profiles include
calcium carbonate, potassium chloride, sodium chloride, choline chloride, taurine, zinc oxide,
ferrous sulfate, vitamin E, vitamin A. vitamin B12, vitamin D3, riboflavin, niacin, calcium
pantothenate, biotin, thiamine mononitrate, copper sulfate, folic acid, and pyroxidine.
[0043] Dry and semi-dry companion animal foods may be prepared by a variety of methods.
One such method that is widely used on commercial basis is the cooker-extruder method. In
the cooker-extruder method, dry ingredients are first blended together to form an admixture.
This admixture is transferred into a steam conditioner where it is sufficiently moistened to
become extrudable. The admixture then enters a cooker/extruder where it is cooked at an
elevated temperature and pressure for a short period of time and then forced out of the
apparatus through a die. This die forms the extruded product into a specific shape.
[0044] Individual pieces of product are created by periodically slicing off the end of the
extruded stream of product. The individual pieces, or kibbles, are then dried in a hot air
dryer. Generally, the product is dried until it contains less man about 15 percent moisture,
and preferably about 5 to 12 percent moisture. The resulting pebbles or kibbles constitute the
food composition.
[0045] With dry and semi-dry companion animal food products, the dried particles or pieces
are then transferred by bulk conveyor to a coating drum and sprayed with animal fat. Other
liquids such as, for example, citric acid or phosphoric acid may alternatively be applied to the
pieces, or applied with or in addition to the animal fat, during or after which a coating of the
palatability enhancer is typically applied.

[0046] The coating need not be a continuous layer, but preferably is uniform. After the fat
cools, if not included with the fat coating, the palatability enhancer may be applied as either a
dry power or a liquid, or both, while the product is mixing. A liquid palatability enhancer is
typically sprayed on while a dry palatability enhancer is typically dusted on, preferably
through a mesh screen to make the application more uniform on the particles or pieces.
Alternatively, a palatability enhancer can be mixed with the fat and applied concurrently.
Note that multiple coatings may be applied to achieve uniformity of the coating.
[0047] For extruded products, the palatability enhancer may be contacted with the livestock
feed or companion animal food ingredients before extrusion by adding dry palatability
enhancer to the ingredients during blending or steam conditioning, or adding aqueous
palatability enhancer solution to the cooker/extruder. Aqueous palatability enhancer solution
may also be applied to the extruded particles or pieces.
[0048] Moist companion animal food products that are gravy based are prepared by
grinding meat, meat mimetics or meat by-products and then forming the ground mixture via
low pressure extrusion through a steaming tunnel where it is cooked. Starch and binders are
then added, after which the mixture is cut into pieces, mixed with water or gravy, sealed in
cans and cooked in a hydrostat, continuous retort or rotary steritort
[0049] Moist companion animal food products that are not gravy based are prepared by
macerating meat, meat mimetics or meat by-products and re-forming the macerated materials
with water, starch and binders. The mixture is then sealed in cans and cooked in a hydrostat,
continuous retort or rotary steritort.
[0050] Semi-moist products are prepared by macerating and mixing meat, meat by-products
or meat mimetics, precooking the mixture, and then mixing the product with humectants such
as glycerol, polysorbate, tween, and spans to hold water. The resulting mixture can be formed
and put into a can or pouch for retorting or press-formed and cooked or retorted in a pouch.

[0051] For purposes of the present invention meat and meat by-products are defined as
including meat and meat by-products from animal species and fish species. Examples of
animal meat and meat by-products for which palatability can be improved by the method of
the present invention include, but are not limited meat and meat by-products derived from
beef, pork, sheep or lamb, poultry, duck, and the like. Examples of fish products and fish by-
products that can be used include, but are not limited to. products and by-products derived
from tuna, salmon, cod, whitefish. shrimp, and the like.
[0052] Examples of unsaturated animal fats and oils and vegetable oils for which palatability
can be improved by the present invention include animal fats such as tallow, chicken fat and
lard and vegetable oils such as canola oil, sunflower oil. safflower oil, cotton seed oil, canola
oil, linseed oil, soybean oil, olive oil. corn oil, and the like, and byproducts thereof. Examples
of animal oils include marine oils and byproducts thereof, such as marine oils from sources
such as menhaden, herring, mackerel, caplan, tilapia, tuna, sardine, Pacific saury, krill,
salmon, anchovy, skate, whale, seal, crab, shrimp, lobster, eel, mollusk, and the like. Vege-
table oils also include oils derived from marine vegetation such as algae, kelp and the like.
[0053] The methods and compositions of the present invention optionally include one or
more additional palatability enhancing compounds, examples of which include
pyrophosphoric acid and the sodium, potassium, calcium and magnesium salts thereof,
phosphoric acid and the sodium, potassium, calcium and magnesium salts thereof, sodium,
potassium, calcium and magnesium tripoly-phosphate salts, potassium, calcium and
magnesium hexapolyphosphate salts, or organic acids such as citric, tartaric, fumaric, lactic,
acetic, formic and hexamic acids and the sodium, potassium, calcium and magnesium salts
thereof, and the like. Examples of suitable palatability enhancing compositions are disclosed
in U.S. Pat. App. Publication No. 2005/0106285 published May 19. 2005, the disclosure of
which is incorporated herein by reference.
[0054] Moist companion animal food compositions are also included that have been
contacted with a palatability enhancer, preferably prior to cooking. Preferred products are
contacted with a palatability enhancer by contacting raw materials before such raw materials
are added to the food product.

[0055] The palatability enhancers of the present invention contain from about 0.1% to 80%
by weight of one or more palatability enhancing compounds, examples of which are listed
above. Palatability enhancing compound levels between aboul 5 and about 50% by weight
are preferred, with levels between about 10 and about 35% by weight more preferred, and
levels between about 15 and about 30% by weight even more preferred.
[0056] The palatability enhancers are formulated and applied so that the one or more
palatability enhancing compounds constitute from about 0.01 to about 500 ppm by weight of"
the finished pet food product. Preferably, the palatability enhancers are formulated so that
the one or more palatability enhancing compounds constitute from about 0.1 ppm to about
0.05% by weight of the finished pet food product, more preferably between about I to about
100 ppm by weight, and even more preferably between about 2 and about 40 ppm.
[0057] Among the preferred palatability enhancers according to the present invention are
palatability enhancers containing from about 5 to about 99 wt.% of one or more products or
by-products selected from the above described meat products, meat by-products, meat
mimetics, dairy products and dairy by-products. Examples of dairy products and dairy by-
products that can be used include, but are not limited to, products and by-products derived
from cheese, milk protein, whey, and the like.
[0058] Preferred products and by-products that may be present alone or in combination
include products and by-products of beef and poultry. Fish products and by-products are also
preferred. A product or by-product level between about 20 and about 70 wt.% is preferred.
[0059] Among the same or other preferred palatability enhancers according to the present
invention are palatability enhancers containing from about 0.01 to about 60 wt.% of one or
more amino acids. Examples of amino acids that can be used include, but are not limited to,
alanine, glycine, cysteine. and the like. Preferred amino acids that may be present alone or in
combination include glycine, L-alanine, and the like. An amino acid level between about 0.1
and about 4.0 wt.% is preferred.

[0060] Among the same or other preferred palatability enhancers according to the present
invention are palatability enhancers containing from about 5 to about 70 wt.% of one or more
microbial or vegetable proteins. Examples of microbial proteins that can be used include, but
are not limited to. brewer's yeast, baker's yeast, and the like. Examples of vegetable proteins
that can be used include, but are not limited to. corn gluten, soy protein, soy flour, hydrolyzed
vegetable protein (HVP), and the like. Microbial or vegetable protein levels from about 10 to
about 40 wt.% are preferred.
[0061] Among the same or other preferred palatability enhancers according to the present
invention are palatability enhancers containing from about 0.01 to about 50 wt.% of one or
more carbohydrates. Examples of carbohydrates that can be used include, but are not limited
to, glucose, xylose, fructose, starch hydrolysates. and the like. A carbohydrate level between
about 10 and about 30 wt.% is preferred.
[0062] One example of a preferred formulation has a solids content of from about 10 to
about 40 wt.% of one or more palatability enhancing compounds; about 30 to about 60 wt.%
of one or more products or by-products selected from animal products, animal by-products,
fish products, fish by-products, dairy products and dairy by-products; from about 25 to about
35 wt.% of one or more sources of microbial proteins; from about 1 to about 9 wt.% by
weight bisulfite; from about 0.1 to about 1.0 wt.% of one or more anti-oxidants; from about 2
to about 4 wt.% of one or more amino acids; and from about 0.5 to about 60 wt% of one or
more carbohydrates.
[0063] Dry formulations have a solids content of about 96 wt%. Liquid formulations may be
diluted to a total solids content as low as about 10 wt% with water and preferably to a solids
content no more than about 50 wt% to obtain a viscosity and rheology suitable for spray
application.
[0064] The water content may also be supplied by moisture-containing or liquid components
such as aqueous bisulfite solutions, the amounts of which are selected by well-known
techniques to maintain the solids content of the product. Liquid formulations according to
the present invention have a pH between about 2 and about 9. Preferred liquid formulations
have a pH between about 2 and about 3.
[0065] For example, a fonnula for a palatability enhancer derived from chicken byproducts
according to the present invention is as follows:

10 to 90% by weight chicken byproducts digest;
2 to 15% by weight phosphoric acid, 75%;
0 to 10% by weight expansion water:
1 to 7% by weight sodium hydroxide. 50%;
0.5 to 10% by weight xylose 40% solution;
0 to 5% by weight 1-cysteine hydrochloride;
0.34% by weight sorbic acid 20% solution:
0 to 2% by weight thiamine; and
0.01% by weight mixed tocopherols, 50%.
[0066] To make a liquid palatability enhancer formulation according to the present
invention, for example, commercially available liquid ingredients are combined in a mixer.
Wet ingredients are ground or emulsified to a slurry and the liquid ingredients are combined
therewith. A commercially available protease may be added to the slurry to hydrolyze
proteins, and later inactivated with heat, acid or another method. Preservatives such as sorbic
acid can also be added. Water is added to adjust the viscosity and the solids content of the
slurry to facilitate spray application. The wet palatability enhancer is sprayed onto the
product so as to achieve a uniform coating and permitted to dry.
[0067] A dry formulation of the palatability enhancer is prepared according to one
embodiment of the present invention, by combining commercially available dry ingredients,
including the palatability enhancing compound, dry metabisulfite, amino acids, inorganic-
salts and organic materials in the desired proportions in a batch mixer and blending to
homogeneity prior to drying.
[0068] According to another dry formulation embodiment, wet and dry ingredients are
combined by mixing the wet ingredients with all or some of the dry ingredients in a mixer
until a homogenous mixture is formed. The mixture is dried by evaporation or lyophilization,
for example, to form a dry, powdery product that is then blended with any remaining dry
ingredients in a tumbler until a homogeneous mixture is formed.

[0069] The following non-limiting examples set forth below illustrate certain aspects of the
invention. These examples are not intended to limit the scope, but rather to exemplify
preferred embodiments. All parts and percentages are by weight unless otherwise noted and
all temperatures are in degrees Celsius.
EXAMPLES
Example 1: Preparation of a Chicken Byproducts-Derived Palatability Enhancer
[0100] A reaction mixture of chicken byproducts digest, xylose solution, 1-cysteine
hydrochloride, and thiamine was prepared using the following amounts:

The pH of the mixture was adjusted to 8 using the sodium hydroxide solution.
[0101] The reaction mixture was then steam heated to a temperature between 90 °C and 100
°C to initiate the reaction. Steam contributed to the formula weight in the form of condensed
expansion water. The reaction mixture was held at the target temperature for 90 minutes for
the development of desirable meaty aromas. The resulting palatability enhancer was
preserved using the formulated amounts of phosphoric acid, sorbic acid solution, and the
mixed tocopherols.
Example 2: Palatability Testing of Byproducts-Derived Enhancer vs. Liver-Derived Enhancer
[0102] In a first formulation, a commercially-available standard dry dog food (Crosswind
Industries. Kansas) was coated with 2% (wt/wt) of the palatability enhancer prepared

according to Example 1. In a second formulation, the standard dry dog food was coated with
2% (wt/wt) of a commercial palatability enhancer derived from poultry liver.
[0103] A panel of approximately 20 dogs was presented with the two formulations in a
standard two-bowl, two-day, free choice method. The consumption by the subject dogs was
at parity for the two formulations.
Example 3: Palatability Testing of Byproducts-Derived Enhancer vs. Byproducts Digest
[0104] In a first formulation, a commercially-available standard dry dog food (Crosswind
Industries, Kansas) was coated with 29c (wt/wt) of the chicken byproducts digest used as the
starting material for preparing the palatability enhancer described in Example 1. In a second
formulation, the standard dry dog food was coated with 2% (wl/wt) of a commercial
palatability enhancer derived from poultry liver.
[0105] The palatability testing was conducted as described in Example 2. The subject dogs
preferred the liver-derived control flavor to the byproducts digest with a consumption ratio
of about 2.8 to 1 and a first-choice ratio of about 5.3 to 1.
Example 4: Palatability Testing of Byproducts-Derived Enhancer with 2ppm 2-Methyl Furan
vs. Liver-Derived Enhancer
[0106] In a first formulation, a commercially-available standard dry dog food (Crosswind
Industries, Kansas) was coated with 2% (wt/wt) of the palatability enhancer prepared
according to Example 1, which had been spiked with 2 ppm 2-methyl furan. In a second
formulation, the standard dry dog food was coated with 2% (wt/wt) of a commercial
palatability enhancer derived from poultry liver.
[0107] The palatability testing was conducted as described in Example 2. The subject dogs
preferred the 2-methyl furan/byproducts-derived flavor with a consumption ratio of about 1.7
to 1 and a first choice ratio of about 2 to 1.
Example 5: Palatability Testing of Byproducts-Derived Enhancer with 0.02ppm 2-Methyl
Furan vs. Liver-Derived Enhancer
[0108] In a first formulation, a commercially-available standard dry dog food (Crosswind
Industries, Kansas) was coated with 29c (wt/wt) of the palatability enhancer prepared
according to Example 1, which had been spiked with 0.02 ppm 2-methyl furan. In a second

formulation, the standard dry dog food was coated with 2% (wt/wt) of a commercial
palatability enhancer derived from poultry liver.
[0109] The palatability testing was conducted as described in Example 2. The subject dogs
again preferred the 2-methyl furan/byproducts-derived flavor with a consumption ratio of
about 1.4 to 1 and a first choice ratio of about 2 to 1.
[0110] From the preceding description of various embodiments of the present invention, it
is evident that the objects of the invention are attained. Although the invention has been
described and illustrated in detail, it is to be clearly understood that the same is intended by
way of illustration and example only and is not to be taken by way of limitation. Accordingly,
the spirit and scope of the invention are to be limited only by the terms of the appended
claims.

WHAT IS CLAIMED:
1. A method for producing a palatability enhancer for a companion animal food
product comprising combining at least one aroma chemical selected from the group
consisting of 2-methylfuran, 2-methylpyrrole, 2-methyl-thiophene and dimethyl disulfide
with an animal or vegetarian digest composition.
2. The method of claim 1, further comprising (a) combining at least one reducing
sugar with said at least one aroma chemical and said digest composition to form a mixture;
and (b) heating the mixture to initiate a reaction process.
3. The method of claim 2 wherein said aroma chemical is added to the mixture
prior to or following heating.
4. The method of claim 1 or 2 further comprising applying said palatability
enhancer to a pork base, a chicken base, a vegetable base, a fish base, or a mixture thereof.
5. The method of claim 1 or 2, wherein said animal digest composition
comprises viscera selected from the group consisting of pork viscera, chicken viscera, and a
combination thereof.
6. The method of claim 2. further comprising at least one sulfur-containing
compound selected from the group consisting of cysteinc. cystinc, glutathione, methioninc,
thiamine, sodium sulfide. and ammonium sulfide.
7. The method of claim 2. wherein said at least one reducing sugar is selected
from the group consisting of xylose, rhamnose, glucose, fructose, and ribose.
8. The method of claim 2, wheiein said mixture is heated to between about 60 °C
and about 180 °C.
9. The method of claim 8. wheiein said mixture is heated to between about 90 °C
and about 130 °C.
10. The method of claim 2. wheiein said mixture is heated for a period of about 1
minute to about 4 days.
11. The method of claim 2. wherein said reaction process is performed at a pH of
between 2.5 and 10.
12. The method of claim 11, wherein said reaction process is performed at a pH of
between 6 and 9.

13. The method of claim 1. further comprising combining said palatability
enhancer with a basal composition containing organosulfite salts formed by contacting
unsaturated fatty acids that oxidize to form aldehydes or ketones in the basal composition
with a source of bisulfite anions.
14. The method of claim 1 further comprising extruding said palatability enhancer
with a basal composition to form a dry or semi-dry kibble.
15. The method of claim 1 further comprising applying said palatability enhancer
to the surface of a kibble after the kibble is extruded.
16. A method for improving the palatability of a cooked moist companion animal
food product comprising contacting said food product with a palatability enhancer prepared
according to the method of claim 1.
17. The method of claim 16, wherein said palatability enhancer is contacted with
said food product prior to cooking.
18. The method of claim 1, wherein said food product further comprises an
additional palatability enhancing composition.
19. The method of claim 18. wherein said additional palatability enhancing
composition comprises a palatability enhancing quantity of one or more compounds selected
from the group consisting of pyrophosphoric acid, polyphosphoric acid salts, phosphoric acid,
phosphoric acid salts, acid tripolyphosphate, tripolyphosphate salts, acid hexapolyphosphate,
hexapolyphosphate salts, citric acid, citric acid salts, tartaric acid, tartaric acid salts, fumaric
acid, fumaric acid salts, lactic acid, lactic acid salts, acetic acid, acetic acid salts, formic acid,
formic acid salts, hexamic acid and hexamic acid salts.
20. The method of claim 1, wherein said food product comprises a food-grade raw
meat or meat by-product.
2 1. The method of claim 20, wherein said meat or meat by-product is selected
from the group consisting of meat and meat by-products derived from beef, pork, sheep,
lamb, poultry, duck, tuna, salmon, cod. whitefish and shrimp.
22. The method of claim 1. wherein said food product comprises an animal or
vegetable fat or oil.

23. The method of claim l, wherein said method is a batch process.
24. The method of claim 1. wherein said method is a continuous process.
25. An extruded companion animal food composition comprising the palatability
enhancer prepared according to the method of claim 1.
26. A moist cooked companion animal food composition comprising the
palatability enhancer prepared according to the method of claim 1.

A method for producing a palatability enhancer for a companion animal food product, wherein the method includes combining at leasl one aroma chemical selected from 2-methylfuran, 2-methylpyrrcle, 2-methyl-thicphene and dimethyl disulfide with an animal or vegetarian digest composition. Companion animal food products containing the palatability enhancer arc also
disclosed.