Note: Descriptions are shown in the official language in which they were submitted.
~ 1 72092
Case 2854
DESCRIPTION
PALATABILITY OF DOG FOOD INCREASED BY
SELECTIVE TREATMENT OF MEAT MEAL
Technical Field
05 The present invention relates to dog food;
particularly, to an improved process for preparing
dog foods which may contain corn, wheat, soybean oil
meal or meat meal and to the product of that process
Because of its nutritional value and relative
economy, corn and soy have been widely employed as
an ingredient in pet foods, particularly dog foods.
Despite their advantages, however, the amount of
corn or soy which could practically be employed in a
dog food composition has been limited because they
tended to reduce overall palatability. Some dog
foods attempted to gain palatability using larger
amounts of more costly ingredients such as whole
grain wheat or meat meal. But these ingredients
have limitations as to their relative amounts that
may be employed in a pet food. For example, meat
meal~cannot exceed a certain limit because the ash
content becomes too high which results in the cal-
cium and phosphorous levels not being properly
balanced in the dog food. This has imposed a major
constraint in dog foods because, despite the ability
of pet food formulators to prepare nutritionally-
balanced rations containing lower costing ingre-
~k
~ 1 72092
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dients, the rations must be sufficiently palatableto assure that the dogs will consume enough to
provide normal growth and maintenance. There is a
present need for an improved process for preparing
05 dog foods containing corn, soy, wheat or meat meal
which is capable of increasing the overall palata-
bility of the dog foods.
Background Art
A number of prior art patents describe dog food
formulations containing corn, soy, meat meal, or
wheat. These products are typically expanded by the
use of an extruder to obtain a porous structure
caused by the combined gelatinization of the starch
and the release of steam upon extrusion. The condi-
tions are typically chosen to assure sufficientstarch gelatinization to achieve the desired expan-
slon .
In U.S. Patent 3,119,691 to Ludington et al, a
uniform dry mix of farinaceous and proteinaceous
ingredients are pretreated by injecting steam to
obtain a mixture temperature of from 200F to 220F
and vigorously agitating the mixture to achieve at
least partial gelatinization of the starch granules
in the farinaceous materials. It is indicated that
the partial gelatinization causes the starch gran-
ules within the mixture to swell under the influence
of increased moisture and heat. The course of the
partial gelatinization can be followed by observing
the individual starch granules when illuminated by
polarized light and viewed through a microscope. As
the reaction proceeds, the granules swell and it can
be noted that the so-called maltese-cross configura-
tions within the granules substantially disappear.
The partial gelatinization does not, however, cause
rupturing of a substantial percentage of the indivi-
! 1 720~ 2
dual starch cells. Following this pretreatment, themixture is subjected to mechanical working under
elevated temperature and pressure, such as in a
screw-fed extruder, and is then discharged through a
OS die to ef~ect the final shaping and expansion of the
product wherein all of the materials have been
subjected to essentially the same conditions of heat
and moisture.
According to another prior art procedure,
Linskey in U.S. Patent 3,139,342 prepares a uniform
mixture of raw wheat grains and other dog food
components such as meat meal, and again subjects the
entire mixture to essentially the same conditions of
heat and moisture. However, according to this
procedure, the materials are simply moistened and
blended prior to feeding them into an extruder.
Heat is not overtly added prior to the extruder
stage, and the starch is therefore not gelatinized.
To achieve proper gelatinization to assure uniform
expansion, an extruder is employed which provides
for a residence time of about 2 minutes during which
the uniform admixture of ingredients is heated to a
temperature of above 212F at a pressure of from
about 100 to 200 psi at a moisture content of from
about 13% to 32%. Again here, the corn is subjected
to the same duration of exposure to heat, moisture
and pressure as are the other ingredients of the
mix.
In U.S. Patent 4,190,679 to Coffee et al, there
is disclosed the production of a dual-textured pet
food containing both a soft portion and a hard,
crunchy portion. Both of these portions preferably
contain corn, wheat, soybean oil meal and meat meal,
and subject the entire mixture to the same condi-
tions of moisture and heat. A pretreatment process
--- ! 172092
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of the type described by Ludington et al may be
employed or the ingredients can be subjected to heat
in the extruder only. It has been our experience
with products of this type, that increasing the
05 amount of corn or soy at the expense of removal of
wheat or proteinaceous materials such as meat and
meat meal, has the effect of decreasing the palat-
ability of the pet food. It would be desirable to
add increased levels of corn or soy bean oil meal
without the expected adverse effect.
It would also be desireable to attain an in-
crease in the level of palatability of the dog food
by treating the wheat, or meat meal.
Disclosure of Invention
The present invention is directed to providing
an improved process for preparing a dog food of
increased palatability.
One part of this invention is achieved accord-
ing to an improved process for the preparation of anutritionally-balanced dog food comprising from 20~
to 80% farinaceous ingredients comprising corn and
at least one additional starch-containing ingredient
and 20% to 80% proteinaceous ingredients, wherein
these ingredients are vigorously mixed under condi-
tions of moisture, elevated temperature, time and
pressure to form an extrudable mass, and the result-
ing extrudable mass is forced from an area of elevat-
ed pressure through an orifice into an area of
sufficiently lower pressure to cause expansion of
the mass and formation of a cohesive product, where-
in the improvement comprises: hydrating a first
portion of ingredients comprising at least a portion
of the farinaceous material, other than a major
portion of the corn, to between 20% to 50% moisture;
~ 1 72~92
heating said first portion of ingredients to between
100F to 190F prior to the addition oE said major
portion of corn; and then adrnixing a second portion
of ingredients, comprising said major portion of the
05 corn, with the first portion for a period of time
sufficient to provide a uniform admixture prior to
extrusion.
The present invention also provides an improved
nutritionally-balanced dog food prepared according
to the above process. According to a preferred
embodiment, the first portion of ingredients will
include ingredients selected from the group consist-
ing of wheat, meat meal, soy bean oil meal and
combinations thereof in an amount of at least 10%,
lS of the product formula and corn in an amount of from
0% to 25% of the total amount of corn in the pro-
duct. More preferrably at least 51% of the total
amount of the soybean oil meal, wheat, or meat meal
will be added to the first portion of ingredients.
20Another embodiment of this invention is achiev-
ed according to an improved process for the prepara-
tion of a nutritionally-balanced dog food comprising
from 20% to 80% farinaceous ingredients and 20% to
80% proteinaceous ingredients, comprising meat meal
and other proteinaceous ingredients, wherein these
ingredients are vigorously mixed under conditions of
moisture, elevated temperature, time and pressure to
orm an extrudable mass, and the resulting extrud-
able mass is forced from an area of elevated pres-
sure through an orifice into an area of sufficiently
lower pressure to cause expansion of the mass and
the formation of a cohesive product, wherein the
improvement comprises: hydrating a first portion of
ingredients comprising meat meal that is to be used
in the dog food to between 20% to 50% moisture,
` ~ ~72092
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heating said first portion of ingredients to between
100F to 190F prior to the addition of other ingre-
dients of the dog food and then, admixing the remain-
ing ingredients, with the first portion for a period
05 of time sufficient to provide a uniform admixture
prior to extrusion.
The present invention also provides an improved
nutritionally-balanced dog food prepared according
to the above process. According to a preferred
embodiment, at least 51% of the total amount of the
soybean oil meal, wheat or combinations thereof will
be added to the meat meal in the first portion of
ingredients.
An additional embodiment of this invention is
achieved according to an improved process for the
preparation of a nutritionally-balanced dog food
comprising from 20% to 80% farinaceous ingredients
comprising wheat and other farinaceous ingredients
and 20% to 80% proteinaceous ingredients, wherein
these ingredients are vigorously mixed under condi-
tions of moisture, elevated termperature, time and
pressure to form an extrudable mass, and the result-
ing extrudable mass is forced from an area of elevat-
ed pressure through an orifice into an area of
sufficiently lower pressure to cause expansion of
the mass and the formation of a cohesive product,
wherein the improvement comprises: hydrating a first
portion of ingredients comprising wheat that is to
be used in the dog food to between 20% to 50% mois-
ture, and heating said first portion of ingredientsto between 100F and 190F prior to the addition of
other ingredients of the dog food, and then admixing
the remaining other ingredients, with the first
portion for a period of time sufficient to provide a
uniform admixture prior to extrusion.
' ~72~9~
The present invention also provides an improved
nutritionally-balanced dog food prepared according
to the above process. According to a preferred
embodiment, at least 51% of the total amount of
05 soybean oil meal will be added to the wheat in the
first portion of ingredients.
Another part of this invention is achieved
according to an improved process for the preparation
of a nutritionally-balanced dog food comprising from
20% to 80% farinaceuos ingredients and 20% to 80%
proteinaceous ingredients, comprising soy bean oil
meal and other proteinaceous ingredients wherein
these ingredients are vigorously mixed under condi-
tions of moisture, elevated termperature, time and
pressure to form an extrudable mass, and the result-
ing extrudable mass is forced from an area of elevat-
ed pressure through an orifice into an area of
sufficiently lower pressure to cause expansion of
the mass and the formation of a cohesive product,
wherein the improvement comprises: hydrating a first
portion of ingredients comprising soy bean oil meal
that is to be used in the dog food to between 20% to
50% moisture, heating said first portion of ingre-
dients between 100F and 190F prior to the addition
of other ingredients of the dog food and then admix-
ing the remaining other ingredients, comprising
corn, meat meal and wheat with the first portion for
a period of time sufficient to provide a uniform
admixture prior to extrusion.
The present invention also provides an improved
nutritionally-balanced dog food prepared according
to the above process. According to a preferred
embodiment, at least 51% of the total amount of the
soy bean oil meal used in the dog food will be in
the first portion of ingredients.
~ 1 720~2
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Based on our experience with the preparation of
starch-based pet foods, we had theorized that there
might be some optimum degree of treatment to which
each of the various ingredients which makes up the
05 pet food should be processed to provide the optimum
degree of cook. For example, we had noticed that
some of the starchy materials were fully gelatin-
ized, while others were not. We believed that it
might be necessary to subject some of the materials
to more controlled gelatinization conditions than
current practice suggested.
To avoid the need to process all of the mater-
ials under most severe conditions at the expense of
large amounts of energy, it was determined that the
most energy-efficient course would be to examine
each of the materials independently to determine the
extent of treatment necessary to gelatinize each of
the individual starch-bearing components. To test
this hypothesis, and the effect of the various
treatments on the palatability of the final products
when fed to dogs, each of several major ingredients
was subjected to processing conditions varying from
no treatment to more extensive treatment than is
typical. Surprisingly, we found that while palat-
ability was improved by treating individual ingre-
dients such as soybean oil meal, meat meal, and
wheat, palatability was decreased as the severity of
the corn processing conditions was increased.
The decrease in palatability caused by the
presence of corn is most pronounced in products
prepared by extruder expansion, such as those dis-
closed in the above identified patents to Coffee et
al, Linskey and Ludington et al. This is apparently
due to the normal tendency of those skilled in the
art to subject the mixture of ingredients uniformly
! 1 7~0~2
g
to quite severe starch gelatinizing conditions. The
finding that palatability is improved by lowering
the severity o treatment of corn as opposed to
these other ingredients could not have been predict-
05 ed on the basis of current knowledge. In addition,the data shown in the examples below shows that when
only moderate heat and moisture treatments of wheat,
meat meal and soybean oil meal occurs, palatability
improves.
The usual designations of pet foods as dry or
intermediate moisture are not of special signifi-
cance to this invention. The products can have any
desired moisture so long as sufficient levels of
preservatives are employed to stabilize them against
microbiological deterioration.
For the sake of conciseness in description, the
entire description contained in the Coffee et al
u.S~ Patent will
not be repeated herein. The following
description will center upon the preparation of a
dry, crunchy, expanded dog food generally in accord-
ance with the description of Coffee et al but improv-
ed according to the present invention. Also, while
not repeating this entire description with regard to
a soft, meat-containing dog food, products of this
type can also be prepared. A combination of the
soft and hard portions is suitable for use as a
dual-textured dog food of the type described by
Coffee et al.
The dog foods of the present invention are
nutritionally balanced. It is important that each
ration be nutritionally complete. Where this can be
assured by the manufacturer, it is not necessary for
the dog owner to balance the guantities of different
foods supplied. The nutritional intake of the dog
A
! t 72Q92
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is then assured so along as it intakes a minimum
amount of food. Nutritionally-balanced foods will
contain protein, carbohydrates, fats, vitamins and
minerals in amounts established by feeding tests to
05 be sufficient for proper growth and maintenance. A
preferred product of the invention will meet the
nutritional requirements as set forth in Handbook
Number 8, entitled, Nutrient Requirement of Dogs,
which is published and amended by the National
Research Council of the National Academy of
Sciences.
To assure that the dog actually consumes the
minimum required amount of food over a period of
time, it is essential that the food be palatable.
The nutritionally-balanced dog foods prepared accord-
ing to the present invention will be prepared by
expansion from an extruder to obtain a porous tex-
ture which, when dried to a moisture content of less
than about 10%, provides a hard, crunchy texture;
but when not dried to this extent or when infused
with a plasticizing agent such as propylene glycol
can provide a meat-like texture. The meaty texture
can be further enhanced by the presence of function-
al proteins to provide more resilience. The foods
will also preferably have a coating of a gravy-
forming material or a fat-based palatant.
Among the farinaceous materials which can be
employed according to this invention are wheat,
corn, barley, oats, etc. and their usual milling
forms and derivatives. The term corn is meant to
encompass all of those varieties of corn typically
employed in animal food compositions as are des-
cribed in the official publication of the Associ-
ation of American Feed Control Officials, Incorpor-
ated. Among these are those varieties known by the
! 1 72092
scientific names Zea mays, including the variety
known as white corn; Zea mays indentata, also known
as dent yellow corn; and Zea mays indurata, also
known as flint corn.
05 Because the finding that minimizing the extent
of corn processing prior to extrusion improves the
palatability of the final product as p~rceived by
dogs, the corn employed according to the invention
should be essentially raw and uncooked. Corn which
has undergone treatment which would tend to gelatin-
ize the starch to any significant degree cannot be
effectively improved by the process of the present
invention. Similarly excluded from the term corn
are derivative products such as corn germ meal, corn
gluten, corn syrup, or the like. The corn and other
farinaceous ingredients can be employed as flours,
meal, and other whole ground grains.
Typically, the total amount of farinaceous
ingredients based on the weight of the total dog
food is between 20% and 80%, preferably 35% and 75%,
by weight, with the corn comprising from about 50%
to about 80% of the weight of the farinaceous ingre-
dients, and from 15% to 60% of the weight of the
total product. Because the corn is preferably
treated to an extent which does not permit signifi-
cant starch gelatinization, it is necessary to
employ sufficient other binding agents, such as
starch-containing materials or functional protein
ingredients, which are capable of providing the
desired cohesiveness in the overall product. Wheat,
for example, is preferably employed at a level of at
least 10% of the total product weight.
The proteinaceous ingredients used may be of
vegetable, animal or fish origin, and typically
comprise soybean oil meal, soy grits, soy flour meat
~ 1 7209~
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meal or fish scrap. Where a soft, cohesive product
ls desired, the prot~inaceous ingredients will
typically comprise various meaty materials including
meat and meat by-products as set forth in the noted
05 Coffee et al patent and as defined in the official
publication of the Association of American Feed
Control Officials, Incorporated. Typically, the
proteinaceous ingredients will comprise from 20% to
80%, preferably from 25% to 55%, of the weight of
the final product.
In addition to these materials, the preferred
formulations will also contain vitamin and mineral
supplements necessary to provide balanced nutrition.
Additionally, where moisture contents in excess of
about 10% axe desired, various osmotic and anti-
mycotic agents will be employed in effective amounts
to assure stability against microbial growth in
accordance with the teachings of the Coffee et al
patent as well as U.S. Patent 3,202,514 to Burgess
et al, and Franzen et al in U.S. Patent 4,212,894.
In processing the formulation according to theinvention to form a dry, crunchy product, a pre-
ferred procedure would be that described by Coffeeet al but modified according to the teachings of
this invention. A major portion for meat meal,
wheat, corn, and soybean oil meal is defined as
greater than 51% of the amount of the respective
component to be used in the total product.
one aspect of this modification, amounts to
withholding at least a major portion of the corn
from the process until a first portion of the ingre-
dients comprising at least ~he farinaceous material
other than the major portion of corn is heated to
,?`~
-
I 1 72092
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between lOO~F to 190F and hydrated to between 20%
to 50% moisture. Then, a second portion of ingre-
dients, comprising the major portion of corn, is
admixed with the first portion to provide a uniform
05 admixture prior to extrusion.
It is preferred that the second portion will
comprise substantially all of the corn. If desired,
a small amount of the corn, amounting to from about
5% to about 30% of the total weight of the corn, can
be enzymatically digested by reacting it with amy-
lase under conditions effective to convert some of
this portion into glucose and oligosaccharides.
Additionally it is desired to enzymatically react a
blend of farinaceous materials, typically corn and
wheat, at a weight ratio of from about 4:1 to about
3:2. It has been discovered that at this particu~ar
preferred b~ending of farinaceous ingredients,
higher than expected palatability is derived than
when these individual ingredients are separately
treated and then combined. These ratios require the
corn to be present from 60-80% and the wheat to be
present from 20-40% by weight on a solids basis of
the farinaceous ingredients to be enzyme treated.
This enzymatically-digested portion can then be
combined with the first portion prior to further
processing.
The proteinaceous ingredients can be added to
the first portion in their dry form and therewith
subjected to moist heat. However, it is preferred
where dry meat meal is employed to enzymatically
react the meat meal. Likewise, the soybean oil meal
may also be enzymatically reacted prior to incorpora-
tion into the first portion.
Another preferred modification is a procedure
to selectively treat meat meal with heat and mois-
1 1 72092
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ture. More specifically, at least 51% of the meat
meal should be hydrated to between 20% to 50% mois-
ture by weight and heated from 100F to 190F. More
pre~errably, greater than 70% of the meat meal is
05 hydrated to between 35% to 50% moisture and heated
to 110F to 180F. It is essential that the meat
meal not be heated over 190F because to do so would
detract from the palatability of the resulting dog
food.
Another embodiment of this aspect is to combine
a major portion of the meat meal with a major por-
tion of the soybean oil meal, wheat or combinations
thereof. The selective treatment of the meat meal
and soybean oil meal, or meat meal and wheat mixture
is hydrated from between 20% to 50% moisture by
weight and heated from 100F to 190F. More prefer-
ably said mixture is heated to 110F to 180F and
hydrated to between 35% to 50% moisture by weight.
More preferrably the three-component mixture of meat
meal, soybean oil meal, and wheat is heated to 110F
to 180~F and hydrated to between 35% to 45% moisture
by weight. If desired, the meat meal can be enzymat-
ically reacted with a protease under conditions
effective to convert a portion to peptides. It is
further desireable to perform a partial proteolytic
digestion of a portion of the meat meal in the
presence of a farinaceous enzymatic reaction slurry.
This enzymatically digested protion can then be
combined with the first portion prior to further
processing.
An additional aspect of the modification would
entail a preferred procedure of selectively pre-
treating wheat with heat and moisture. More speci-
fically, at least 51% of the wheat should be hy-
drated to between 20% and 50% moisture by weight and
! 1 72092
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heated from lOO~F to 190F. More preferrably,greater than 70% of the wheat is hydrated to between
35% to 50% moisture and heated to between 110F to
180~F. It is essential that the wheat not be heated
05 over 190F because doing so detracts from the palat-
ability of the resulting pet food product.
Another embodiment of this aspect is to combine
a major portion of the wheat with a major portion of
the soybean oil meal. The selective treatment of
the wheat and soybean oil meal mixture is hydrated
to between 20% to 50% moisture by weight and heated
from lOOeF to 190~F. More preferrably, said mixture
is heated to llODF to 180~F and hydrated to between
35% to 50% moisture by weight. The selective treat-
ment for the combined wheat and soybean oil meal isto hydrate to between 20% to 50% moisture by weight
and heated to between lOOdF to l90~F. If desired,
the portion of the wheat can be enzymatically re-
acted with a amylase under conditions effective to
convert a portion into glucose and oligosaccharides.
It is fur~her desireable to perform an amylolytic
digestion of from about 10% to 35% of the total
weight of the wheat. This enzymatically-digested
portion can then be combined with the first portion
i 2S prior to further processing.
Another preferred modification is a procedure
to selectively treat a major portion of the soy with
heat and moisture. More specifically, at least 51%
of the soy to be used in the dog food should be
hydrated to between 20% to 50% moisture by weight
and heated from lOO~F to 1906F. More preferrably,
greater than 70% of the soy is hydrated to between
35% to 50% moisture and heated to llO~F to 180~F.
It is essential that the soy not be heated over
l90~F because to do so would detract from the palat-
E 1 72Q92
- 16 -
ability of the resulting dog food. If desired, a
portion of the soy can be enzymatically reacted with
a protease under conditions effective to convert it
into peptides. This enzymatically-digested portion
05 can then be combined with the first portion prior to
processing.
The precise mechanism which is responsible for
the improvements is not fully understood at this
time.
Some of the data suggests a correlation between
the achievement of the improved results and the
maintenance of the corn in a substantially ungela-
tinized state throughout the process. While it is
not known whether the mechanism responsible for
gelatinization is also directly involved in the
palatability improvement achieved, it is consisten-t
with the data to maintain the major portion of the
corn separate from the other farinaceous ingredients
and the proteinaceous ingredients during the initial
stages of gelatinization of the other farinaceous
ingredients. This is shown in Table III, wherein
corn receiving no selective treatment had an average
consumption difference of 4.18 compared with the
control. By comparison, there was only a 0.70
average consumption difference between corn receiv-
ing a selective treatment as compared with the
control. It is also shown in Table IV wherein corn
receiving no selective treatment and wheat receiving
a selective treatment resulted in an average consump-
tion difference of 6.41; whereas when both corn andwheat received a selective treatment the average
consumption difference was only 0.26. It is also
consistent with the data to maintain the corn sepa-
rate from various other ingredients such as wheat,
soybean oil meal and meat meal during the period of
~ 172~92
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time that they take on the majority of final process
water, thereby making them water-rich while main-
taining the corn water poor. This is shown in Table
II wherein the product in which corn received no
05 selective treatment was better in palatability than
the product which contained corn which had been pre-
treated.
Parts of the data presented in tables II, III,
and IV suggest that selectively treating the meat
meal will increase the palatability of the dog food.
This is clearly shown in Table III, wherein the meat
meal receiving a selective treatment had an average
consumption difference of 3.62 compared with the
control. By comparison, there was only a 1.26
average consumption difference between meat meal not
having a selective treatment as compared wlth the
control. It is also shown in Table IV, wherein meat
meal receiving a selective treatment and corn having
no selective treatment resulted in an average con-
sumption difference of 5.54; whereas when both cornand meat meal did not have a selective treatment,
the average consumption difference was only 2.83.
These findings are completely unexpected because the
commercial production of the meat meal re~uires that
ground meat and bone meal be heat treated and it is
not obvious to further treat the meat meal by a
further moderate heat treatment and moisture. The
prior art as represented by Ludington et al, teach
that the meat meal should be combined with the other
components of the pet food and sub;ected to severe
heat and moisture treatment. Ludington et al do not
suggest or teach that palatability may be improved
by treating the individual ingredients with a moder-
ate heat and moisture treatment.
~ 17209~
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Other parts of the data presented in Tables II,
III, and IV suggest that selectively treating the
wheat will increase the palatability of the dog
food. It is ~hought that selectively treating the
05 wheat component will better allow for its hydration.
Normally the wheat would be in competition with the
other hydroscopic ingredients when mixed in combina-
tion with all ingredients as taught by Ludington et
al. It is hypothesized that when the wheat receives
a controlled hydration of temperature and moisture,
the enzymes naturally present in the wheat may
affect it both chemically and physically and/or a
more controlled gelatinization may occur which may
be involved in the palatability improvement. It is
consistent with the data to maintain the wheat in
combination with meat meal and/or soybean oil meal
so long as the mixture of wheat and soybean oil meal
or wheat and meat meal or wheat, meat meal and
soybean oil meal receives the selective treatment of
molsture and heat. In Table II, it is shown that
when only wheat and meat meal receive a selective
treatment the resu~ting average consumption differ-
ence from the control is 7.97. Likewise when only
wheat and soybean oil meal receive a selective
treatment, the resulting average consumption differ-
ence from the control is 7.47. The palatability
preference is not as strong when wheat, soybean oil
meal and meat meal are combined together and select-
ively treated. This is shown in Table II wherein
such mixture is shown to have an average consumption
difference of 5.28 from the control. In Table IV,
the average of all test samples that have both wheat
and meat meal selectively treated, regardless of the
teratments to the other ingredients of soybean oil
meal and corn, resulted in an average consumption
difference of 3.47.
' 172092
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Also in Table IV, the average of ali test
samples that have both wheat and soybean oil meal
selectively treated, regardless of the treatments to
the other ingredients of meat meal and corn, result-
05 ed in an average consumption difference of 4.95.
Additional data presented in Tables II, III,and IV suggests that selectively treating soybean
oil meal will increase the palatability of the dog
food. Again, this is shown in Table III, wherein
soybean oil meal receiving a selective treatment had
an average consumption difference from control of
3.87 as compared to 1.01 average consumption differ-
ence from control for soybean oil meal having no
selective treatment. It is presently not known why
one obtains this increase in consumption of the dog
food.
These comments are offered for the purpose of
explaining the phenomenon to the greatest extent
possible by applicants; however, applicants do not
wish to be bound to any particular theory or mechan-
ism by which the invention provides its unexpected
results.
Typically, all of the major dry farinaceous and
proteinaceous ingredients are ground and stored
separately for blending in the desired ratios.
While the exact grind size is not critical, it has
been found that grinding the ingredients to a size
that at least 80%, and preferably when at least 85%
passes through a 20 mesh U.S. Standard Sieve, pro-
vides a desirable balance between raw materialhandling and final product performance character-
istics. Grind sizes substantially larger than this
cause products that have visually discrete par-
ticles, and also processing is sometimes more diffi-
cult due to less effective hydration of the largerparticles.
t 1 72092
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From their individua~ storage bins, it is
preferred to feed substantially al~ of the farina-
ceous materials and 0% to 49% of the corn along with
the proteinaceous materials such as soybean oil meal
05 and meat meal to a dry batching apparatus wherein
~he ingredients are agitated sufficiently to provide
a uniform dry blend, designated herein as a first
portion of ingredients. ~ore preferrably 0% to 25%
of the corn to be used in the process will be added
to the first portion of ingredients. As noted
above, however, it may be desirable to enzymatically
treat a small portion of the corn and any desired
amount of the meat meal prior to combining them with
dry materials to form the first portion of ingre-
dients.
The first portion of ingredients is then pre-
ferrably sub;ected to a selective treatment wherein
the moisture content is increased to within the
range of from about 20~ to about 50%. More preferr-
ably, the moisture content is increased to withinthe range of from 35% to 50% by weight. In addition
to increasing the moisture content of the first
portion of ingredients, the first portion is heated
to a temperature which typically falls within the
range of from about lOO~F to about l90~F, prefer-
rably within the range of from about llO~F to about
180~F. This selective treatment rapidly hydrates
the first portion and can partially gelatinize the
starch granules within the farinaceous materials.
The step of treating the first portion of
ingredients in the presence of moisture and heat can
be wholly accomplished within the barrel of an
device such as a Wenger mixer. The basic nature of
the process is not altered simply by the fact that
one piece of equipment is employed as opposed to two
1 1 72092
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or more pieces. The corn is subject to less severe
processing in terms of moisture and heat exposure
than is necessary for the other ingredients. ~here
the meat meal and/or a portion of ~he corn or possi-
bly another part of the farinaceous ingredients is
05 enzymatically reacted prior to admixture to form the
first ingredient portion, sufficient water for
forming an extrudable mass may be provided by these
materials alone. If not, the additional moisture
can be added either in the preconditioner or in the
subsequent plasticizing and extrusion stages by the
addition of water or steam.
The major portion of the corn which has been
withheld from processing in the first portion of
ingredients is then admixed with the first portion
for a period of time sufficient to provide a uniform
admixture prior to extrusion from the die plate into
the zone of lower pressure.
In the extruder, which may be a Wenger cooker-
extruder or an Anderson expander, the combined
admixture of the first and second portions of ingre-
dlents is subjected to mechanical working under
pressure at elevated temperatures, generally above
212F and typically between 240F to 300bF. Where
necessary to achieve the proper plastic consistency
within the extrudable mass, additional moisture can
be added in the form of heated water or steam.
Preferably the moisture content of the extrudable
mass just prior to extrusion will be within the
range of from about 20% to about 30%.
After a residence time within the screw-fed
extruder of from about 15 to about 120 seconds,
typically from about 30 to about 60 seconds, the
extrudable mass is forced from the area of elevated
pressure within the extruder through an orifice into
! 1 72092
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an area of sufficiently lower pressure to cause
expansion of the mass and the ~ormation of a cohe-
sive product. The product exits the extruder
through a suitable die of desired size and shape to
OS form what is known in the art as an expanded rope
structure havlng a moisture content reduced from
that present in the extruder due to flashing off of
moisture as steam. The flashing of moisture is also
responsible for the expanded texture of the product.
The product will typically be severed as it is
extruded and will then be dried to the desired
moisture content. For a dry product which does not
re~uire any preservatives, moisture contents Q~ less
than about 10%, typically 8% to 9%, are preferred.
lS Where suitable osmotic and anti-microbial agents are
employed, moisture contents may be selected as
desired, typically from 10% to about 25% by weight,
and preferably from about 12% to about 20% by weight
The expanded products will normally have bulk densi-
ties within the range of from about 18 to 30, andpreferably from about 20 to 24, pounds per cubic
foot.
Where desired, these products can be coa~ed
with palatants, such as those which are based upon
fat and or protein, or they can be coated with
various gravy formers as are known to the art.
Best Mode for Carrying Out the Invention
The following examples are presented for the
purpose of further illustratlng and explaining the
present invention and to describe the best mode
presently known for carrying it out. These examples
are not intended to be taken as llmitlng in any
regard. ~nless otherwise indicated, all parts and
' t 72092
- 23 -
percentages are based upon the weight of the product
or portion at the indicated stage in processing.
Example I
This example describes the preparation o~
05 a number of test products, wherein each of the major
proteinaceous and farinaceous ingredients are sub-
jected to a contro~led selective conditioning treat-
ment, and a single test product wherein none of the
farinaceous or proteinaceous ingredients are su~-
jected to a selective conditioning treatment, and~2) a control product of the same formulation, but
inc~uding no selective conditioning. A~l test
products are then fed to a canine testing pane~ ~n a
controlled test versus the control product to deter-
mine their relative palatabilities. The controlproduct contains the following formu~ation and is
prepared according to the followlng process:
Ingredients Parts by weight
Wheat Middllngs 20
Who~e Ground Corn 40
Soybean Oil ~eal 20
~eat Meal 10
~itamin and Mineral Premix 6
Coating 4
The ingredients, with the exception of the
coating ingredients, are mixed and fed to the en-
trance of an Anderson expander operating at temper-
atures up to 280bF. The moisture within the expan-
der is adjusted to a~out 30%. After a residence
time of a~out 120 seconds the mixture exits through
a circu~ar extruder die orifice at a temperature of
about 210~F and a moisture of about 26%. The pres-
sure ~ust before the die orifice ls about 150 psig.
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The now-expanded porous mixture is cut into kibs
a~out 3/4 inch long, 1/2 inch wide, and 5/8 inches
thick, using a cutting knife :rotated in front of the
extruder orifice. The kibs are then placed on a
05 drying belt and dried a~ 250F, and one cooling zone
at ambient air conditions, with the dried kibs
exiting the drier at about 80~F and 10~ moisture.
The coating mixture comprising liquified tallow is
then applied to kibs by mixing and spray-
ing in a fine mist onto the kibs.
The various test products are prepared bytreating each of the ma;or farinaceous and protein-
aceous materials separately and in various combina-
tions in a Wenger mixer at 190F and hydrating the
material to 30% moisture over a time period of 3
minutes prior ~o admixing them and and subjecting
them to extrusion under the same conditions as
~or the contro~.
Tab~e I depicts the design of this study, each
variable having been fed versus a no-treatment
control.
TABLE I
Grid Design
Number of
25 Components Soybean
Pretreated Corn Wheat Oil Meal Meat Mea~
X O O O
O X O O
O O X O
0 0 0 X
X X O O
X O X O
2 X 0 0 X
O X X O
0 X 0 X
O O X X
X X X O
3 X X 0 X
X O X X
O X X X
~ 1 72092
- 2$ -
TABLE I (Cont'd)
Grid Design
Number of
Components Soybean
OS Pretreated Corn Wheat Oil Meal Meat Mea~
All X X X X
None 0 0 0 0
0 = No Pretreatment
X = Pretreatment
The feeding design consisted of two series each
of eight, two-product, 15-dog tests. Overall re
sults of this study are summarized in Tables II, III
and IV, indicated:
. Selective treatment of corn reduced palatabillty.
. Se~ective treatment of meat meal, soybean oil
meal, and wheat increased palatability.
. When the proteinaceous ingredients were treated
along with the wheat, a posltive effect existed
over the treated protein alone.
TABLE II
Individual Variable Palatability Averages
(Note: Ta~le entries are average consumption dif-
ferences over Control (g/kg.-dry). ~0~ refers to no
treatment and '1' refers to treatment). This Table
results ~rom the overall design in Table I wherein
each sample is fed against the control. Pa~atabil-
ity results of greater than 2.5 are considered to be
a preference for the test product.
Soybean
3~ Corn Wheat Oil Mea~ Meat Meal alatability
O O O O -1 . 0
0 0 0 1 4.06
0 0 1 0 - .02
0 0 1 1 4.85
~ 1 7209,~
- 26 -
Soybean
Corn Wheat Oil Meal Meat Meal Palatability
0 1 0 0 4.94
0 1 0 1 7.97
0g 0 1 1 0 7.47
0 1 1 1 5.28
1 0 o 0 -3.68
1 0 0 1 1.83
1 0 1 0 2.04
1 0 1 1 4.34
1 1 0 0 -1.02
1 1 0 1 -4.g8
1 1 1 0 1.43
1 1 1 1 5.61
TABLES III AND IV
Main Effect & 2 Factor Interaction Averages
20(Note: Table entries are average consumption
differences over Control ~g/kg.-dry). i0' refers to
no pretreatment and '1' refers to pretreatment).
The main effect entries are the average of all
tests in which the maln component with the treatment
indicated was compared to a~l other samples, whether
or not the other ingredients in the test samples had
treatments too. Thus, in the case of corn having no
treatment, the average consumption differences of
the eight samples in Table II indicating no treat-
ment, is 4.18 grams per kilogram. Likewise, the 2
factor interaction entries are the average of all
tests which the two components being analyzed re-
ceived the treatment noted whether or not the other
ingredients in the samples had treatments too.
Thus, in the case of wheat and soy both having a
treatm~ent, the average consumption difference of the
four samples in Table I~ indicating treatment for
~oth wheat and soy components results in an average
consumption difference of 4.95 grams per kilogram.
1 172092
- 27 -
TABLE III
Main Effect Averages
Corn 0 = 4.18
1 = .70 (Difference at 9~.5~ confidence
05 leve~)
Soy O = 1.01
1 = 3.37 (Difference at 95% confidence
~eve~)
Wheat 0 = 1.55
1~ 1 = 3.33
Meat 0 = 1.26
Mea~ 1 = 3.52 (Dlfference at 90% confidence
leve~)
TABLE IV
Two Factor Interaction Averages
Wheat
0
Corn a 1 . 96 6.41
1 1.13 .26
20 (Interaction significance at 95% Con~idence Leve~)
Meat Meal
0
Corn 02.83 5.54
1- .31 1.~0
Meat Meal
Wheat 0- .68 3.77
13.20 3.4~
1 t 720~2
- 28 -
Soybean Oil Mea~
O
Corn 03.98 ~.39
1-l.g6 3.36
05 (Interaction slgnificance at 90% Confidence Level)
Soybean Oil Meal
0
Wheat 0 .29 2.80
11.72 4.95
Meat Meal
0
Soybean 0 - .21 2.22
oil mea~1 2.73 5.02
Example II
Based on the results indicated in Example I, a
second grid is designed taking the best and worst
combinatlons of the grid ln Table I in terms of
palatabi~ity results from Table II and varying the
processing conditions to determine the effect on
palatabi~ity. Thls study involves the treatment of
a wheat, meat meal and soybean oil meal combination
and the selective treatment of corn alone. The
parameters lnclude low, medlum, high moisture condi-
tions, as well as, low, and high time-temperatures.
The various samples are outlined in Tables V and ~I.
- 1 172092
~9
- TABLE V
Se~ective Treatment Times at Various Water
Levels for Wheat-Soybean-Oil-Meal ~eat Meal
Temp. _20% 30% 40%
05 l~aF 3 minutes 3 minutes 3 minutes
190F 3 mlnutes 3 mlnutes 3 minutes
190~F lS mlnutes 1~ minutes 15 minutes
Results of this study indicate that the carnine
testlng panel had a hlgher than average preference
for those test samples whereln the wheat, soybean
oil meal and meat meal mixture had been hydrated to
40% over the control of Example I. There are no
signlflcant differences among the three time-temper-
ature ~evels. The interaction is slgnificant at the
1~ 9g% confidence level. The palatability preference
results suggests that at 20% molsture, the cook
appears best at 3 minutes at 190F, whereas at
30-40% moisture the 3 mlnute cook at 170~F ls op-
timal. The averages show there is a possibi~ity of
20 being better than control - the best combinations
being low cook (17~F) and 30-40% moisture.
TABLE VI
Selective Treatment at Various Water Levels
Water Levels for Corn
2~ Temp. 20% 30% 40%
170~ 3 minutes No Sample 3 minutes
19aF No Samp~e 3 minutes No Sample
190F 15 mlnutes No Sample 1~ minutes
All samples lost to control at the 99% confi-
dence level and fell in the "moderatel' loss range.There are no significant differences among any of
the ~ treatment combinations and none of the factor
effects are slgnificant. Thus, selective condl-
tioning adversely affects corn.
~ 1 ~2092
- 3~ -
Example III
To illustrate one preferred method for prepar-
ing a dog food according to the present invention,
the followin~ formulatlon is processed as described
05 below:
HARD, C~UNCHY PORTION
Parts by
Ingredient Welght
Whole Ground Corn 54.~
~0 Whole Ground Wheat 15.0
Meat & Bone Mea~ 14.8
Scybean Meal, 44~ protein 12.0
~itamin and Mineral Premix 2.1
Liquid ~lant Protease 0.15
15 Bacterial Amylase 0.002
Fungal Amy~ase 0.00
Color System 0.02
Liquid Coating 5.0
A dry blend of 44~ soybean meal and the whole
ground wheat is prepared in a mixer. Simultaneously
with the preparation of this dry blend, 4 pounds of
the approximately 54 pounds of corn is fe~ with an
equal weight of water and the bacteria~ and fungal
amylases into a stirred reactor. The reaction
mixture is heated to l406F and held at that temper-
ature for about 30 minutes. To this farinaceous
reaction s~urry, about 55% of the meat and bone meal
is added along with an equal amount of water. The
resulting combined reaction slurry is again heated
to 140~F, and one half of the liquid plant protease
ls added at this temperature. After a reaction time
of about 20 minutes, the other half of the liquid
protease and the remaining meat and bone meal are
added for a second period of reaction of about 2~
minutes at 1406~. Thereafter, the reaction mixture
~ 1 7209~
is heated to 170~F and held there for three minutes
to inactivate the enzymes. At this stage, the
combined reaction slurry has a moisture content of
about 50%.
~5 The resulting combined reaction slurry is then
fed from reactor into a Wenger-mixer precondltioner
wherein it is combined with the dry blend from dry
mixer. The majority of the corn is withheld from
treatment at this stage in processing. After a
residence time of about 45 seconds at a temperature
of about 130F in the preconditioner, this first
portion of ingredients is then fed to an Anderson
expander. A~so fed to the expander is a second
portion of ingredients whlch comprises the remainder
lS of the who~e ground corn. ~ithin the expander, a~
of the ingredients are mechanica~ly worked under
heat and pressure to provide a uniform extruda~e
mass. The temperature within the expander is main-
tained at about 2~0DF and the mixture is extruded
through an arc-shaped orifice to expand to just ~ess
than twice its initial vo~ume while curving in the
direction of extrusion as well as transverse~y
thereto.
A ~lade positioned in scraping contact with the
2~ die p~ate, intermittent~y passes the opening in the
die plate and severs the produc~ into c~amshel~-
shaped pieces havlng approximate~y the fo~lowing
dimensions: one-half inch ~y three-fourths inch ~y
one inch dried to a moisture content of about 9% in
a single pass continuous belt drier, and then the
produc~ is coo~ed to a temperature of about 80~F
passed into coating a ree~ wherein it is sprayed
with ~ pounds of a ~iquid coating comprising beef
tal~ow and enzymatical~y reacted fat and proteln.
3~ From the coating ree~, the resulting dog food pieces
are co~ected for packaglng.
1 1 7209~
- 32 -
The above descriptlon is for the purpose of
teaching those skil~ed in the art how to practlce
the lnventlon and is not lntended to recite all the
possible modlficatlons and variations thereof whlch
05 wl~ become apparent to the ski~led worker upon
reading. It is intended, however, that al~ such
modifications and variations be included within the
scope of the invention which is defined by the
fo~lowlng claims.
