Glazed Liver Coated Biscuit or Kibble for Pets

The field of art to which the invention pertains includes the field of edible material, particularly pet food in the form of bone-shaped biscuits, cookies or kibbles.

This invention relates to novel foods for animals and to methods of making the same. More particularly, it relates to dried farinaceous and proteinaceous meaty products having a substantially higher palatibility than other coated products presently used in the trade. It also has a high nutritional and caloric value and may be used as a maintenance food, stored and marketed in nonrefrigerated containers without the need of hermetically sealed containers. The product can be provided in the form of small kibbles or, as preferred, in greater than bite-size, for example in the form of large, molded bone-shaped pieces. Particularly in the latter form, the product has a uniformly palatable taste throughout, that is, the biscuit is palatable when bitten into as well as when first taken into the pet's mouth. The products do not become mushy when served with liquid but retain their dry, solid characteristics and retain their meaty characteristic.

Dog and cat foods are commonly prepared as either meal-type rations or canned-type rations and are commonly formulated from a combination of proteinaceous and farinaceous materials. The proteinaceous material is derived from either vegetable protein sources or from meat and/or meat by-products, and nutritional supplements are often added. Meal-type animal foods have a dry, cereal-like texture and low moisture content, typically about 10%. They usually have a very high nutritional and caloric value providing a complete balanced diet for the animal, and excellent storage characteristics, thus permitting the use of relatively inexpensive packaging techniques. However, the palatability of many dry meal-type animal foods is poor and, in many cases, the animal will not eat them at all in dry form, necessitating the addition of liquids prior to their consumption. Liquid addition can cause the products to become mushy and on that basis could be rejected by the animal.

Canned-type animal foods having a meat-like texture and high-moisture content are generally received quite favorably by animals, apparently due in part to their meaty-texture, consistency and aroma. However, the elevated moisture content of such products requires thermal processing in sealed containers to obtain a commercially sterile product, thereby adding considerably to product costs. Furthermore, once such a can is opened, it must be quickly consumed since the product is quite conducive to supporting microbiological growth and hence will deteriorate very rapidly unless stored under refrigeration.

In addition to the two foregoing general types of animal foods, intermediate moisture products, having a moisture content in the range of about 15%-30%, have also been made available. In order to avoid microbiological decomposition, such products must be specially processed, e.g. by thorough pasturization, and/or by being packaged in hermetically sealed containers and commercially sterilized, or maintained in a frozen or refrigerated state. Another approach is to disperse an aqueous phase of water soluble solids uniformly throughout the product, the soluble solids being principally sugar at a level high enough to exert a bacteriostatic effect sufficient to stabilize the animal food. Such a product is illustrated by H. M. Burgess U.S. Pat. No. 3,202,514. The high sugar content of such products is not palatable to all animals, nor is it nutritionally sound.

Thus, there has not been provided an animal food product which has the high palatability associated with the meaty texture of canned food and the convenience and high nutritional value associated with meal-type foods. The present invention provides such products. In particular, there is provided a dried cereal based pet food composed of farinaceous and proteinaceous materials encapsulated within a glazed coating composed of liver and farinaceous material, the combination of which has a synergistic effect that excites the taste buds of the pet more than either of the highly palatable ingredients taken separately. In a preferred form, the matrix of farinaceous and proteinaceous material is formed to provide a core of desired shape and baked to less than 18% moisture by weight. While the shaped matrix is extremely hot, i.e. having an internal temperature in excess of 200.degree. F., the product is immersed in a meaty coating of farinaceous material and liver having a lower temperature, causing a sudden drop in temperature which creates a partial vacuum in the inner core of the shaped matrix, drawing the aroma and flavor of the coatng material into the matrix, which is then trapped within the core by a second baking that forms a hard crust of dried meaty substance on the exterior to encapsulate the matrix. More specifically, liver constitutes at least 50% of the coating formulation by weight, exclusive of water. Such a coating not only provides a meaty taste, but also enables formation of a hard, glazed crust, greatly enhancing the product's attractiveness to pets. The liver should be comminuted to form a slurry which can be maintained by the addition of vegetable enzymes as described hereafter.

In a further preferred embodiment, prior to baking the cores are formed from a combination of uncooked farinaceous material and meat by-product in a particular form. Specifically, the meat or meat by-product is uncooked and in the form of finely cut flakes. This is combined with the uncooked farinaceous material, such as wheat, and blended to form a pasty dough which is molded into discrete pieces. The pieces are then baked at a temperature sufficiently high, e.g. 350.degree.-650.degree. F. to provide dry, solid cores having a moisture content of less than 18% by weight. The baked cores are coated with the high liver content coating, as above, then subjected to a second baking step, again at a preferred temperature of about 350.degree.-650.degree. F., to reduce the moisture content, also to less than 18% by weight, preferably to a range between 8% and 18% by weight. The result is a product having high palatability throughout, and having a surface which does not become mushy when immersed in water or other liquid. The product is hard and solid, yet meaty in taste. With the simple addition to the core formulation of an antioxidant and an antimycotic agent, the product can be packaged using relatively inexpensive techniques and stored without spoilage.

It is particularly advantageous for the core to be formed of uncooked (that is other than as a result of the baking step) meat or meat by-product which is in the form of finely cut flakes, preferably having its largest dimension in the range of 15/1000 inch to 250/1000 inch. The flakes are blended with farinaceous material, such as wheat, serving as an adhesive to form a pasty dough, preferably without adding water. In addition, one can add a small amount of a source of edible oil, such as soy oil or soybeans, which not only adds protein but also serves to bring out the meaty flavor and helps with molded pieces in release of the product from the mold. One can also add other ingredients such as ground corn, for example in the form of flour, to add additional flavor and aroma to the biscuit. The following ranges of core ingredients, wherein percentages are by weight, are suitable.

The components are blended to form a pasty dough. To obtain molded biscuits, the dough is fed into a pair of opposing plates defining cavities in the desired shape, such as bones, and then molded therein. The molded pieces are then baked under time and temperature conditions sufficient to form the desired dry, solid, molded product. For example, the pieces can be baked at a temperature of about 350.degree.-600.degree. F. for five minutes to an hour, conveniently in a continuous oven to reduce moisture content to less than 18% by weight, preferably to a range between 8% and 18%. The high temperature used in the baking step is particularly important to achieving a dry solid surface that resists mushing, whereas the prior art has found that palatability suffers when such high temperatures are used (e.g. Ludington et al U.s. Pat. No. 3,119,691). Products of the present inventions have a high degree of palatability perhaps as a result of combining such a high temperature in the baking step with the use of finely cut flakes of meat or meat by-product.

Critical to successful coating in accordance with the present invention is the use of a slurry of comminuted liver, preferably beef liver, in sufficient concentration, at least 50% by weight of the slurry, exclusive of moisture to provide a glazed, encapsulating coating when baked. Vegetable enzyme is preferably added to the coating formulation. Up to about 3% by weight is useful to keep the liver in a liquid state, prevent coagulation and keep it non-fibrous. The enzyme becomes active at 86.degree. F. and deteriorates at 122.degree. F. so that it is lost in baking. One can also add ground whole wheat which acts as a binder to hold the coating together. Various colors and flavoring can be added to simulate different meat flavors and appearances. Antioxidant and antimycotic agents can be added and sufficient water is added to achieve the desired viscosity.

Whether being applied to kibble-like pieces or to the preferred baked combination of uncooked farinaceous material and finely cut flakes of uncooked meat or meat by-product, the combination of high liver content and high temperature baking provides a glazed encapsulation presenting to the animal a highly attractive textural, olfactory and visual combination. Particularly, the preferred double baked product has high palatability throughout. Accordingly, large sized pieces can be provided, greater than bite-size (4 cm. long or larger) which can be bitten into by the animal without loss of palatability.

In its more general form, the product has as its core any dry biscuit, expanded or compressed, obtained by molding, by cold extrusion or by cooking expansion, or otherwise. In the general form of the invention, the core can be meaty or entirely cereal in composition. Central to this general embodiment is the provision of a continuous glazed liver coating, baked to less than 18% moisture by weight, liver preferably constituting at least 50% by weight of the coating, exclusive of moisture. Again in the general form, the cores can be made of any known material and when it is in the form of kibble-like pieces, it can be made entirely of farinaceous materials. See for example the core materials of U.S. Pat. No. 3,808,340, incorporated herein by reference. Preferably, even when in kibble form, the core material is obtained by blending farinaceous material and meat or meat by-product described hereafter. Kibble can be prepared by extrusion through conventional cold forming extrusion equipment to form pieces, for example one inch long and 1/4 inch cross sectional diameter. The extruded pieces can be tumbled to round the edges and then dried by heating in a conventional hot air oven to reduce the moisture content to less than 18% by weight.

In a preferred form of the invention, the product is double baked, the core materials being formed with a combination of (a) uncooked farinaceous material and (b) meat or meat by-product which is uncooked and in the form of finely cut flakes. Meat or meat by-product in this form is to be contrasted with meat or meat by-product which is comminuted by grinding or other such process. The meat or meat by-product can be cut into flakes by processing through a cutting screen wherein pieces are fed by a revolving impeller into contact with sharp vertical knives separated one from another by a distance which provides the preferred size range of 15/1000 inch to 250/1000 inch. Such processing equipment is commercially available, for example, as sold under the trademark "Comitrol" by Urschel Laboratories, Incorporated, Valparaiso, Ind. Such processing is distinct from conventional comminuting apparatus which grinds, crushes, hammers, mashes, tears or rips.

The meat or meat by-product is fed fresh or frozen in small pieces (generally five or six inches or smaller when fresh and two to three inches or smaller when frozen). The output can then be blended directly with various farinaceous and vegetable proteinaceous material without the addition of water.

As meat, one can use any boneless beef, pork, veal, lamb, poultry or fish, either fresh or frozen. Thus, the term "meat" is understood to apply not only to the flesh of cattle, swine, sheep and goats, but also to horses, whales, and other mammals, poultry and fish. The term "meat by-products" refers to those non-rendered parts of the carcasses of slaughtered animals, including but not restricted to mammals, poultry and the like, and including such constituents as liver, kidney, heart, spleen, tongue, trimmings, lungs and skins, embraced by the term "meat by-product" in the Definition of Feed Ingredients published by the Association of American Feed Control Officials, Inc.

It is important that the meat or meat by-product be subjected to a pure cutting action as above referred to rather than to grinding, crushing, hammering, mashing, tearing or ripping. It is the division into finely cut flakes, together with the adhesiveness of the farinaceous material, which provides the unique characteristics giving rise to the resultant high palatability properties of the product.

After the meat or meat by-product is cut into fine flakes, it is blended with the other ingredients, principally with farinaceous material. By "farinaceous material" is meant those foodstuffs containing a preponderance of starch and/or starch-like material. Examples are cereal grains and meals or flours obtained upon grinding cereal grains such as corn, oats, wheat, milo, barley, rice and the various milling by-products of the cereal grains, such as wheat feed flour, wheat middlings, wheat mixed feed, wheat shorts, wheat red dog, oat groats, hominy feed, and any other such material. Also included as sources of farinaceous ingredients are the tuberous foodstuffs such as potatoes, tapioca, or the like. Preferably, the farinaceous material is glutenous such as wheat and serves as an adhesive for the dough, the gluten component providing a tenaceous elastic protein that gives cohesiveness to the dough and enhances the elasticity of the mixture. In addition to wheat, corn flour is an advantageous, inexpensive source of flavoring and aroma which enhances the flavor imparted to the product by the meat or meat by-product. The corn flour also provides additional protein and serves as an additional source of edible oil.

In addition to the farinaceous material, there is added a source of edible oil to enhance the baking of the biscuit and to aid in releasing molded dough from the die. One could use soybean oil, cottonseed oil, corn oil, or other vegetable oil, or one can use a source of such oil such as soybeans which release oil during the molding process. Soy oil or soybeans are preferred as bringing out the flavor of the meat or meat by-product as well as serving as a releasing agent for the molded product.

In addition to the foregoing ingredients, one can advantageously add effective amounts of an antioxidant as normally used in the food industry. For example, one can utilize butylated hydroxytoulene (BHT), butylated hydroxyanisole (BHA), ethoxyquin, or the like, in an amount sufficient to effect the desired antioxidant properties in the product, generally less than 1.0% by weight of the product. In addition to an antioxidant, one may also use an effective amount of an antimycotic as a preservative and mold inhibitor. Examples of such materials include the edible benzoates or propionates, such as sodium benzoate and calcium propionate, as well as sorbate salts, such as potassium sorbate, in an amount sufficient to prevent mold and bacterial growth within the product, each generally less than 1.0% by weight of the product. Salt can be added, e.g. about 0.5-4%, as a natural source of chlorine, to bring out the flavor of the finished product and to aid in preserving the product. Up to 20% animal fat can be added if desired. Additives such as vitamins, minerals and coloring matter may be added at the blending stage although as a result of using the meat or meat by-product and farinaceous and proteinaceous material referred to above, such supplementation is not necessary with the present product.

The ingredients can be blended to a pasty dough, placed into the cavities of a mold and pressed into the desired shape. The shaped product is then placed on the conveyor belt of a continuous oven and passed through a heating zone at 350.degree.-600.degree. F. for a time sufficient to reduce the moisture content to less than 18% by weight, preferably to a range of between 8%-18%.

The core material, whether kibble-like in size and form or whether molded as biscuits, is coated with a slurry of comminuted liver. In this regard, the slurry contains liver, preferably beef liver, as its key and major component. The liver is comminuted which can be conveniently carried out in the Comitrol described above or by any other process. It is suspended in a solution of water to form a slurry and may be supplemented by a variety of other ingredients. For example, other meat or meat by-product components, such as spleen or the like can be added. One can add meat tenderizer to soften the fibrous material in the liver. Soy oil can be added to contribute to gloss and sheen. One can add ground broken cores obtained from prior processing, as well as food colors of various types to simulate the visual appearance of various meat coatings. Antioxidants and antimycotic agents can also be added. One can also add such ingredients as whole egg or glycerine to provide additional glazing. Condiments such as garlic and onion can be added as can charcoal flavoring or the like.

The cores are dipped into the liver slurry by being carried therethrough on a porous belt but other methods could be used such as tumbling or the like. Preferably, particularly when the cores are formed of the aforenoted combination of cut flakes of uncooked meat and uncooked farinaceous material, the cores are dipped into the cooler coating liquid while the cores are at a temperature greater than 200.degree. F. preferably while the cores are hot from the prior baking step. This serves to cause a sudden drop in temperature of the outer surfaces of the cores extending into the cores and creating a partial vacuum in the matrix of each core, drawing the aroma and flavor of the coating material into the matrix. This flavor and aroma is trapped within the cores by the subsequent baking step which forms a hard crust of glazed, dried meaty substance on the exterior to encapsulate the matrix. Following application of the coating, the product is baked for a time and temperature sufficient to reduce the moisture content to less than 18% by weight. Thus the product can be placed on the conveyor belt of a continuous oven and passed through a heating zone at 350.degree.-600.degree. F. In the preferred form of the invention, when a double baking cycle is used, the coating can be applied as the molded cores are emerging from a first continuous baking oven and then fed into a continuing section of the oven to complete the second baking step. The coating constitutes about 2-20% by weight of the product.

The following specific examples, in which all percentages are by weight, will further illustrate the invention:

The following ingredients are blended to form a pasty dough:

The uncooked beef spleen is fed into a Comitrol 2100 meat processing machine equipped with a cutting head in which the separation of the vertical blades is 90/1000 inch to yield cut flakes of the meat by-product 90/1000 inch in their largest dimension. The wheat is ground in a Prater Pav 10C rotary centrifugal mill with a 2 mm. screen. The soybean meal is ground through a 30/1000 inch screen in the Comitrol. The above ingredients are then placed in a mixer and blended to a pasty dough which is placed into a mold and shaped into bones about 4 inches long. The bones are then baked in a continuous oven 150 feet long at 500.degree. F. for 17 minutes to yield dry solid molded pieces having a moisture content of less than 18 weight percent and having high palatability throughout.

While still hot, the molded pieces are led immediately into a slurry bath containing the following ingredients:

The beef liver constitutes 60.7% of the coating formulation, exclusive of moisture. It is ground through a 3-K 30030-D screen in a Comitrol. The ground beef liver and water are then put in a high speed mixer and mixed for 2 minutes. The vegetable enzyme is then added to the mixture which is then mixed again for 2 minutes at high speed. The remaining materials are added and the combination is mixed at high speed for 3 minutes to obtain a slurry. The resulting bath is maintained above 80.degree. F., the activation temperature of the enzyme, but below 122.degree. F., the enzyme deterioration temperature.

The molded pieces as they emerge from the 150 foot oven are led through a bath containing the above slurry and then led into another section of continuous oven 50 feet long and baked at 460.degree. F. for six minutes. The product is then cooled in a cooling tower to a temperature of 70.degree. F. to 90.degree. F. and then packaged. The product is of high palatability throughout and has a continuous glaze with the appearance and flavor of glazed beef. The uncoated "bones" weight about one ounce each, the coating adding about 10% by weight.

The procedure of Example 1 is repeated except that the slurry has the following ingredients:

The beef liver constitutes 60.2% of the coating formulation, exclusive of moisture. The product obtained has the visual surface appearance and flavor of glazed liver.

The procedure for Example 1 is followed except that the slurry has the following ingredients:

The beef liver constitutes 62.0% of the coating formulation, exclusive of moisture. The product has the surface appearance and flavor of glazed chicken.

The following ingredients are blended to form a pasty dough:

The beef liver is ground through a 30/100 inch screen in a Comitrol 2100 meat processor. The wheat and milo are ground in a Prater Pav 10C centrifugal mill with a 2 mm. screen. The soybean meal is ground through the 30/100 screen of the Comitrol. The ingredients are placed in the mixer and blended into a pasty dough. After mixing thoroughly, a moisture run on the product is found to be between 32% and 33%. The product is placed in a mold and shaped into bones which are then baked in a continuous oven at 500.degree. F. for 17 minutes to yield cores having a moisture content of less than 18%.

While still hot the molded pieces are led into a slurry bath containing the following ingredients:

The beef liver constitutes 67.8% of the coating formulation, exclusive of moisture. The slurry is prepared and applied, and the product is baked and packaged, following the procedure of Example 1. The result is a product having the surface appearance and flavor of glazed beef.

The procedure of Example 4 is followed except that the slurry has the following ingredients:

The beef liver constitutes 68.5% of the coating formulation, exclusive of moisture. The product has the surface flavor of bacon and egg.

The procedure of Example 4 is followed except that the slurry contains the following ingredients:

The beef liver constitutes 67.0% of the coating formulation, exclusive of moisture. The product has the surface appearance and flavor of beef.

Cores are prepared from the following ingredients:

The core material is blended and then extruded through conventional cold forming extrusion equipment to form small pieces approximately one inch long and 1/4 inch cross sectional diameter. The extruded pieces are then tumbled to round the edges and then dried by heating in a convectional hot air oven at 250.degree. F. for 30 minutes. The pieces are then tumbled in a pan-coating machine containing a slurry having the following ingredients:

The beef liver constitutes 68.6% of the formulation, exclusive of moisture. The cores and slurry are tumbled together for approximately 3 minutes so the coating is dispersed evenly over the surface of the core material. The coated cores are then baked at 450.degree. F. for 6 minutes in a continuous oven to produce a product having a glazed liver coating.

The procedure of Example 7 can be repeated substituting the core material of Example 1 for that used in Example 7.

The procedure of Example 1 can be repeated substituting horse meat, deboned chicken and deboned fish, respectively, for the beef spleen.