Note: Descriptions are shown in the official language in which they were submitted.
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This fnvention relates to a process for i~proving
the palatability of dry pet food. More particularly, this
invention relates to a process for enhancing the flavour of dry
pet food so that the acceptance thereof by cats is increased.
It should be understood that the expression "dry
pet food", as used herein, includes such foods having low or
intermediate moisture contents as distinguished from pet foods
having relatively high moisture contents which are generally
packaged in containers impervious to liquids.
Dry pet foods exhibit a number of advantages over
pet foods having higher moisture contents. The dry foods are
generally more nutritious on an e~ual weight basis, require less
expensive packaging, have better keeping ~ualities and are more
convenient to use.
Domestic animals, particularly cats, are notoriously
fickle in their food preferences. As a result, their owners
frequently change types and brands of cat food in order to main-
tain their pets in a healthy and contented condition. For the
most part, the only way to determine the gastronomic preferences
~f cats is by trial and error.
There are a-number of processes disclosed in the
art for improving the palatability and other characteristics
of dry pet food. U.S. Patent 3,115,409 to Ballinan et al, is
directed to pet foods having a high acid content for improved
palatability and to impart stability to elevated processing
temperatures. The hydrogen ion concentration of the food is
adjusted by incorporatlng therein an edible acid or acid salt.
U.S. Patent 3,139,342 to Linskey relates to an animal food pro- -
cess wherein the food is produced in the form of pellets which
may be coated with various taste enhancing and/or nutrition
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supplementing materials, e.g., fat and vit~min A. U.S. Patent
3,203,806 to Youn~ relates to a pet food having acetamida and
acetic acid incorporated therein for improved palatability.
The palatability improvers may be a~ded to dry or semi-dry pet
foods by being sprayed thereon. U.S. Patent 3,615,647 to
Kessens is directed to a porous, expanded animal food in the
form of chunks coated with fat which coating is, in turn, over-
laid with a coa~ing of dextrin. U.S. Patent 3,679,429 to
Mohrman et al relates to a method for improving the palatability
of dry cat food by coating particles of the food with fat and a
flavour enhancing acid, specifically, citric, phosphoric or
hexamic acid. U.S. Patent 3,708,306 to Appleman relates to a
pet food containing psyllium by products wherein dicalcium phosph-
ate is incorporated. The dicalcium phosphate is blended into
the pet food together with other ingredients in the form of a
batter which is then baked. U.S. Patent 3,930,031 to Kealy is
directed to a cat food composition having a coating comprising a
flavour enhancing mixture of phosphoric and citric acids.
In general, cats seem to exhibit a preference for
foods having an acidic reaction. The degree of acceptance of a
food is apparently determined largely through the cats highly
developed sense of smell. Materials applied to the surface of
dry pet food affect its acceptance by cats to a greater degree
than do the same materials incorporated into the body of the
food. Presumably, this is due to the fact that the cats' --
olfactory organs can more readily detect the smell of these - ~ -
materials when such are on the surface of the food.
The application of certain acids to the surface of ;
~ dry cat food, while apparently having a positive effect on
palatability, is not entirely =atisfactory. Such acids present
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handling problems and, since they are corrosive, expensive
equipment must be used in processes employing -the same. More-
over, since the acids are applied in liquld ~orm they may dif-
fuse into the body of the food upon storage, thus reducing their
effect on palatability and acceptance.
Accordingly~ it is a principal object of the present
invention to provide a process ~or improving the palatability of
dry pet food.
It is yet another object of the present invention
to provide a process for lmproving the palatability of pet food
to cats which does not requlre expensive processing equipment.
It is still another object of the present invention
to provide a pet food having improved palatability to cats.
These ob~ects and other objects which will be appar-
ent from the following description and claims~ are achieved by
providing on the surface of the pet food a sufficient amount of
a salt of phosphoric acid to enhance the ~lavour of the food and
increase the acceptance thereo~ by cats.
According to one aspect of the invention there is
provided a process for improving the palatability of dry pet
food comprising providing on the surface of the food a sufficient
amount of a salt of phosphoric acid to enhance the ~lavour of
the food and increase the acceptance thereof by cats. -
Accordlng to another aspect of the invention there
is provided pet food having enhanced palatability of cats com-
prising dry pet food having a salt o~ phosphoric acid applied
to the surface of the ~ood.
Salts of phosphoric acid which may be used to advan-
tage in the present process are those having an acidic reaction.
Examplary of such salts are the monoalkali metal and monalkaline
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earth metal salts of phospho,rlc acid,
The salt of phosphoric acid may be applied as such
directly to the surface of the pet food. ~lternatively, the
salt may be formed on the surface o the pet food in sitù by
applying thereto salt forming materialsr e,g.~ alkali and phos-
phoric acid, and adjusting the acidity thereof as desired.
The amount of the salt of phosphoric acid applied
to the surface of the pet food to enhance the flavour thereof
will vary depending, inter alia~ on the composition of the food
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and the par~icular salt utilized. Typically, the amount used is
such that a 10 percent aqueous slurry of the food will have a pH
in the range of from about 4.5 to about 5.5. The preferred pH
is about 5.2. While the present invention is not limited to the
application of any specific amount of a salt of phosphoric acid,
it is contemplated that not more than about 5 percent of the salt,
based on the weight of the food, will be applied since larger
amounts do not appear to provide any additional benefits. The
preferred amount is in the range of from about 0.25 to about 2.0
percent and the most preferred amount is about 0.75 percent.
It is contemplated that the food to which the salt of
phosphoric acid is applied will most suitably be in bite size,
particulate form, such as pellets and the like. The salt may be
applied to dry pet food having any shape or form. However, the only
requirement being that at least a portion of the surEaces of the
food have the salt applied thereto. Although the present invention
is principally directed to the use of salts of phosphoric acid to
improve the palatability of dry pet food and increase its accept-
ance by cats, other materials which together with the phosphoric
acid salts impart the set forth acidity may be used. Such materials
include acids such as phosphoric and citric acids and various
other edible acid salts.
The surfaces o~ the pet food may also be treated with
other flavor enhancing materials. Typically, the pet food will be
coated with fat, e.g., animal tallow, or with flavourings, e.g.,
meat or cheese flavors and the like, colorants, etc.
Dry pet foods may be prepared by a variety of methods.
One such method which is widely used on a commercial basis is the -
~- cooker-extruder method wherein the ingredients are first blended
and moistened to provide an extrudable mixture. The mixture is
then fed into an apparatus wherein it is heated and extruded in
the form of particulates which are then dried. Any of the materials ;~
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conventionally used to prepare pet foods may be used. Typically,
these include sources of proteln, carbohydrate, and fat, which are
generally derived from both animal and vegetable sources, minerals,
vitamins, flavorants, colorants, preservatives, etc.
The sal~ of phosphoric acid may be applied to the surface of
the pet food in any convenient manner, such as spraying, dustiny
and the like, so that the ~alt is applied to at leas-t a portion of
the food. Generally, the acid salt will be applied to the pet food
after such is coated with a fat so the desired degree of adhesion
will be obtained. A solution of the salt may be utilized and, in
thi$ case, the solution can he sprayed onto the pet food. Convenient-
ly, the food, carried on a moving belt, passes beneath a hopper
from which metered amounts of the salt are deposited on the surface
of the food. The process of the present invention may be carried
out in a batch or continuous manner.
In order to more clearly describe the nature of the present
invention, specific examples will hereinafter be described. It
should be understood, however, that this is done solely by way of
example and is intended neither to delineate the scope of the inven-
tion nor limit the ambit of the appended claims. -~
Example 1
This example illustrates a continuous process for producing
dry pet food having enhanced palatability to cats by applving to
the surface of the food a salt of phosphoric acid.
Dry pet food ingredients comprising poultry by-products,
ground corn, wheat flour, fat, corn gluten meal, salt, cheese powder,
whole egg, dried milk, organ meats and vitamin and mineral supple-
ments were blended. The blended ingredients were mois~urized and
steam conditioned to a moisture content of about 30 percent in the
pre-cooker section of an expander cooker-extruder. The moisturized
pet f~od was then metered into the cooker-extruder and extruded
through appropriately shaped dies to provide pieces having the
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desired shape and size. The shaped pieees were dried to a mois~ure
content of less than about 12 percent, eoolecl and spray-eoated with
a fat in a revolving cylinder. The fat coated pieces were then
plaeed on a moving belt which passed beneath a hopper containing
crystalline monosodium phosphate from which a sufficient amount
of the phosphate salt was deposited onto the surfaee of the food
to provide a coneentration thereon of about 0.5 pereent monosodium
phosphate based on the weight of the food.
Example II
This Example illustrates the effeet on aeeeptability by
eats of applying a-salt of phosphorie aeid to the surfaee of dry
pet food and eompares the aeeeptability of such food with that of
a commercial dry cat food having phosphoric aeid on its surface.
Dry pe-t food was prepared as shown in Example ~ but with
suffieient amounts of salts of phosphoric acid applied to the
surfaee of portions thereof to provide the following, based on
the weight of the food:
A - 0.25 percent monosodium phosphate
B - 0.5 percent monosodium phospha-te
C - l.O percent monocalcium phosphate
Groups of 8 to lO cats were individually housed and pro-
vided with separate feed pans eontaining weighed amounts of -the
eo~ereial cat food and one of the phosphate salt treated cat
feeds enumerated above. The cats were allowed free choice of the
eat foods for a period of 24 hours. The pans were then removed
from the eages and the amounts of eaeh food eonsume~ by eaeh
eat were determined. The above proeedure was then repeated for
a seeond 24 hour period. The eombined results of the two day
feeding tests are shown in Table I below:
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The data in the above Table show~ that, in
general, the cats in the paired feedlng tests showed a pre-
ference for the pet food prepared by the process of the
present invention,
Example III
This Example illustrates the storage stability
of dry pet food which has been surface treated with a salt
of phosphoric acid and compares said storage stability with
tha-t of a commercial pet food which had been surface trea-ted
with phosphoric acid.
Twenty cats were individually housed and pxovided
with separate feed pans containing weighed amount~ of dry
pet food coated with sufficient sodium acid phosphate to
provide 1.0 percent thereof on the surface of the food and a
commercial dry pet food, respectively. The cats were allowed
free choice of the pet foods for a period of 24 hours. The
pans were then removed from the cages and the amounts of
each food consumed by each cat were determined. The above
procedure was then repeated for a second 24 hour period.
The test pet foods were stored for two months at
a temperature of 85F and then presented to 19 of the cats in
two 24 hours feeding periods identical to those described
above. The results are shown in Table II below:
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From -the above table, it is apparent that the cats
showed a strong preference for the sodium acid phosphate
treated food. This preference is even more dramatically
evidenced when the cats were provided with the two foods
following storage thereof at two months at 85F.
The terms and expressions which have been employed
are used as terms of description and not of limitation. It
is not intended, in the use of such terms and expressions to
exclude any equivalents of the features shown and described
or portions thereof, since it is recognized that various modi-
fications are possible within the scope of the invention
claimed.
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