IES79062B2 - A mouldable dog food ingredient - Google Patents

Abstract

A mouldable dog food which eliminates the need to use gelatin, has a pH adjusting step and forms a stable food product which maintains its shape, is prepared from a nutritionally balanced mixture of casein, starch, fat, vitamins and minerals, a pH adjusting agent, a phosphate and sufficient water to bring the water content within the range 5 to 20% w/w so as to be easily handled within an extruder and moulding machine, wherein it is heated to approximately I00‹C to fully cook and gelatinise the food ingredient. It is then extruded under high pressure conditions injected into a mould and coated to form an easily digestible, nutritious, stable food product which is cohesive and maintains its shape. The extruder comprises a feed screw 20 with a check ring 22 adjacent the injector nozzle and the diameter of the screw D1 increases D2 adjacent the check ring for smooth transition of the feed to the injector nozzle.

Description

The present invention relates to a dog food and in particular to a mouldable dog food.

There are considerable advantages in preparing a dog food by extrusion and injection moulding. For example, typically an extrusion and injection moulding process comprises preparing a premix having a heat sensitive binding agent and gelatin, delivering the premix to a feed screw, subsequently injecting the mix into a mould and then moulding the product. For example U.K. Patent Specification No. 2 179 589 discloses such an extrusion process where the barrel is cooled and the heat sensitive binding agent remains substantially inactivated and is only activated either on injection or in the mould.

Indeed many food extrusion processes are well known and it has been appreciated for some time that there is a need for a mouldable food product, which is relatively hard such that a dog, for example, can chew it. It is known to provide all sorts of indigestible materials for dogs to chew, even plastics materials. Unfortunately while dogs may enjoy chewing these relatively indigestible products, they are not necessarily good for the dog.

European Patent Specification No. 0 562 193 describes one particular dog food that it is claimed can be extruded and moulded successfully. This dog food it is claimed is of a modifiable hardness and comprises a homogenous mixture of casein and gelatin having a total moisture content of 10-15% and sealed within moisture-proof packaging such that upon removal from the said package and upon exposure to heat the dog chew may be caused to expand and decrease - 2 in hardness. The particular novel feature claimed for this invention is that the dog chew additionally comprises poultry meal and said homogenous mixture comprises 1571.25% poultry meal, 15-71.25% casein and 5-40% gelatin, the combination of the poultry meal and casein amounting to 60-95%. The specification further goes on to explain that in order to cause the ingredients to be intimately combined with one another, the mixture is heated to the components' melting temperatures under pressure and the mixture's moisture content is adjusted by either heating to drive off excess moisture or steam injection to increase the moisture, at which time the material is either extruded or it is suggested preferably moulded into pre-selected shapes. It is also suggested that a standard injection moulding machine is the preferred method for producing the chews.

It is already well known, for example from WO-A-91/16825, for a high protein meal of animal origin to be added as a filler to a casein-gelatin combination and this European Patent No. 0 562 193 suggests that the use of poultry meal is particularly advantageous in that the dog food does not dry out as quickly, as would be expected, and it has an exceedingly extended shelf-life.

U.S. Patent Specification No. 5,480,673 describes a relatively complex way of providing an extruded cooked product while maintaining a high level of desirable soluble protein.

U.S. Patent Specification No. 4,251,556 describes a pet food in which a caseinate binder is partially replaced by a vegetable protein and an amylaceous material.

U.S. Patent Specification No. 4,127,678 describes another way of replacing sodium caseinate again using a vegetable protein.

However, there are still problems in extruding and forming such products and unfortunately the ingredients described in this European Patent Specification No. 0 562 193 are relatively expensive.

The present applicants have found that preferably gelatin should not be used and further it is preferable to alter the pH of the material in the mixture if successful binding is to occur. This is also particularly the case when gelatin is omitted from the mixture. It has long been realised that starches on the application of heat can be gelatinised, but the problem then is they are very difficult to handle in the extruder and in the mould. Further it is known that the solubility properties of casein and its salts are poor in acidic environments, and that the pH should be altered to fall within the range of 6.0 - 8.0 in order to achieve a good degree of mixing. Further it becomes advantageous to alter the pH of the material, in particular where the water activity is above approximately 0.85. Reducing the pH value improves the stability of the food composition where this water activity is high, however a balance must be struck between stability and acceptable pH values for consumption. Indeed it is further known that acidic foods increase plaque and accelerates tooth decay and thus while many of the food products produced for dogs appear of their nature to be suitable, they are in fact too acidic and thus cause increased tooth decay.

A further problem that has become apparent in the moulding of these products is to ensure that there is no clogging within the screw and the basic raw ingredients, when mixed, can be handled in the extruder and can be successfully injected into the mould. Thus, there is a need for producing a product that can be gelatinised without the addition of gelatin and at the same time can be handled in the extruder in such a way as not to cause the build up of materials within the extruder and further to ensure that the premix is adequately mixed and handled within the extruder so as to provide a coherent and cohesive product.

The present invention is directed towards providing a mouldable dog food ingredient and thus a dog food that can be relatively easily handled within an extruder and moulding machine, that incorporates a pH adjusting step which solves the problems caused by high acidity, will not use added gelatin and finally can be efficiently handled within the extruder and mould.

Statements of Invention According to the invention there is provided a mouldable dog food ingredient comprising: % - 84% w/w Starches 0% - 10% w/w Fat 0% - 5% w/w Glycol 15% - 25% w/w Casein 0% - 5% w/w Meat digests 0% - 2% w/w Additives 0% - 1.0% w/w Vitamins 0.5% - 8% w/w Phosphate 0% - 5% w/w Flavouring 0.5% - 5% w/w pH Adjusting agent incorporating calcium and sufficient water to bring the water content of the ingredient within the range 15 to 20% w/w.

This ingredient can be relatively easily handled within an extruder and moulding machine, eliminates the need to use gelatin, has a pH adjusting step, and forms a stable food piece which maintains its shape.

Preferably the water content of the ingredient is brought within the range 16 to 18% w/w.

Further the invention provides a food ingredient comprising: 45% - 55% w/w Starches 2% - 5% w/w Fat 2% - 3% w/w Glycol 18% - 23% w/w Casein 0.1% - 0.5% w/w Vitamins 1% - 3% w/w Phosphates 1% - 3% w/w Flavouring 1.0% - 3% w/w pH Adjusting agent incorporating calcium.

Calcium carbonate is employed as a pH adjusting agent. The advantage of using calcium carbonate is that it provides a good and simple way of altering the pH value and keeping the pH of the mixture within desired levels and has the added advantage of adding calcium to the dog's diet to strengthen bones and teeth. Surprisingly, calcium carbonate appears to prevent clogging within the screw and also provides for improved mixing of the ingredients. Also, it has been found that calcium carbonate improves the hydration properties of the product providing for a wider range in texture of the final product, while at the same time, when subject to elevated pressures, imparts a sturdier structure giving it a higher degree of firmness or chewiness. It has also been found particularly important to ensure that the total water content of the ingredients when they are extruded and thus heated that the water is within this range of 15-20% weight by weight. Another advantage of the present invention is that in many instances the casein content of the product can be kept low and since casein will allow the product to harden and thus provide a sufficiently good chew for the dog it is a vital ingredient. At the same time as casein is relatively expensive ideally it should be used as sparingly as possible while achieving the required hardness .

Further the starches are a mixture of proteinaceous and farinaceous materials in the ratio 1:1.5 and preferably are chosen from: Tapioca Corn Broken rice Wheat flour Potato Rice flour Corn flour Oat flour Sugar beet.

The prior art, US 4,904,495, shows that at a pH above 6, the combination of gelatin and various starches can cause sticking in the mixer. It was found that, without gelatin, this effect was greatly reduced. Also employing potato starch as an inert diluent helps reduce sticking in the extrusion process and overall increases the flowability of the process stream.

Preferably the pH correcting agent is CaCO3.

The fat is preferably an edible oil extracted from meat, fish or a vegetable. Edible oil has been found to be a suitable fat to use for moulding and corn oil, fish oil and wheat germ oil particularly so. They also have the added advantage that they are widely known to be used in the treatment of Vitamin A and E deficiencies.

Preferably additional food preservatives 0-5% w/w are added and these may be chosen from: Potassium sorbate Sodium priopionate Sodium chloride Sorbic acid Glycol.

The phosphates may be chosen from: Monobasic sodium phosphate Monocalcium phosphate Sodium Tripolyphosphate Calcium phosphate Sodium Glycerophosphate Sodium biphosphate.

Desirable food flavourings are chosen from: Meat Digest Cheese Powder Chocolate Chlorophyll Honey Vegetable Propylene glycol Monosodium glutamate Sodium chloride.

Detailed Description of the Invention The invention will be more clearly understood from the following description of some embodiments thereof given by way of example only with reference to the accompanying drawings in which:Fig. 1 is an outline drawing showing an injection moulding apparatus according to the invention, Fig. 2 is a side view of an outline of portion of the mould and barrel housing a feed screw according to the invention, Fig. 3 is a side view of a screw, Fig. 4 is a typical section through part of the screw, and Fig. 5 is a sectional view in the direction of the arrows V-V of Fig. 4.

Referring to Fig. 1 there is provided a moulding apparatus indicated generally by the reference numeral 1 comprising a cooking and feed barrel not shown on this drawing housed within heating bands 2 a food hopper 3 adjacent one end of the feed barrel forming a feed inlet, an injector nozzle 4 at the other end of the feed barrel 2, a mould indicated generally by the reference numeral 5 comprising a fixed platen 6 and a moving platen 7 operated by a locking cylinder 8. An injection cylinder 9 is also provided. All this in general outline is conventional.

Referring now specifically to Fig. 2, it will be noted that each mould platen 6 and 7 is provided with cold water chambers 10 and 11 respectively fed by cold water feed and return pipes 12 and 13 respectively.

Referring now specifically to Figs. 2 to 5 there is illustrated a screw indicted generally by the reference numeral 20 mounted within a feed barrel 30. The screw 20 has a conical head 21 and check ring 22 and threads 23. Three axially arranged slots 24 are formed in the conical head 21. The root diameter is identified by the reference letters DI and D2 and it will be noted that the root diameter increases gradually from the back or entrance of the feed screw 20 towards the head 21 and further the pitch of the screw identified by the letters Pj and P2 decreases in the same direction. Further it will be noted that there is a smooth transition between the last thread and the check ring 22 at 23.

Referring now specifically to Fig. 4 it will be noted that each thread 23 has a leading face 25 which is substantially perpendicular to the longitudinal axis of the screw and a trailing face 26 which forms a smooth inclined surface between the root of the thread identified by the reference numeral 27 and its tip 28. This smooth transition surface subtends a mean angle a in this embodiment of approximately 45° between the screw axis. This angle can be anything from between 30 and 60°, but ideally is between 40° and 50°.

It is envisaged that the mould surface area shall generally speaking be large relative to the mould volume and ideally is in the ratio 3:1. Preferably it is in the range 1.5:1.

In operation a premix as will be described hereinafter is formulated and tested sufficiently to find the approximate water content when cooked. Then sufficient water is added to the ingredient to ensure that the total water content of the ingredient namely the actual water added and the water that will be released during the cooking process is within the range 15 to 20% by weight. The ingredient is then placed in the feed hopper and delivered to the feed screw where it is heated to approximately 100° to fully cook and gelatinise the food ingredient as it progresses down the feed screw. The temperature generally is of around 100°, but may vary depending on the ingredients to between 75° to 125°C, but is more often within the range 95° to 105°C. As the ingredient mixture moves along the feed screw, it is progressively pressurised until all the starches have been gelatinised and the mixture totally cooked, when it forms a liquid which is then injected at a pressure of between 500,000 kp/cm2 to 1,600,000 kp/cm2 and preferably within the range 600,000 kp/cm2 to 1,000,000 kp/cm2 into the mould. The mould which is cold ensures that as the mixture expands into the mould, it also hits a relatively cold mould surface where the product shrinks slightly thus making the product much easier to eject after moulding.

The examples which follow give some samples of the range of ingredients used and some preferred mixes. While the mixes are given as a mouldable dog food ingredient, it will be appreciated that the final product will also have the same ingredient in the same respective ratios by weight, but the final percent of the weight of the total food product will depend on the cooking process and the amount of water evaporated, during the moulding.

TABLE 1 RANGE OF DOG FOOD INGREDIENTS - SOLIDS - 30% weight by weight Protein - 84% weight by weight Starches 0 10% weight by weight Fat % weight by weight Glycol 3% weight by weight additives (including vitamins) % weight by weight Ph Adjusting Agent - 10% (including glycol) weight by weight Flavourings 0-5% weight by weight Phosphates - 5% weight by weight preservatives - 20% weight by weight Water.

TABLE 2 PROTEIN Meat Digest Casein.

TABLE 3 STARCHES Sugar Beet Tapioca Corn Broken rice Wheat flour Potato Rice flour Corn flour Oat flour.

TABLE 4 PRESERVATIVES Potassium sorbate Sodium priopionate Sodium chloride Sorbic acid Propylene glycol.

TABLE 5 PHOSPHATES Monobasic sodium phosphate Monocalcium phosphate Sodium Tripolyphosphate Calcium phosphate Sodium Glycerophosphate Sodium biphosphate.

TABLE 6 FLAVOURINGS Monosodium glutamate Sodium chloride Meat digest Cheese Powder Chocolate Chlorophyll Honey Vegetable.

TABLE 7 FATS Corn oil Fish oil Animal fat Edible oil generally Wheat germ oil.

TABLE 8 ADDITIVES Choline chloride Absorbic acid Vitamin mix Potassium chloride.

TABLE 9 pH ADJUSTING AGENT Calcium carbonate The following table gives details of three specific mixes.

TABLE 10 MIXES Mix 1 Mix 2 Mix 3 Water 7% 8.1% 6% PROTEIN Meat Digest 5% 2.0% 3% Sodium Caseinate 16% 22% 20% STARCHES Potato 16.25% 15% Rice Flour 13% 9% 12% Tapioca 13.5% 9.6% 19.5% 10 Broken Rice 13% 31% 7% PRESERVATIVES Potassium Sorbate 0.5% 0.3% 0.5% Potassium Propionate 0.25% 0.3% 0.75% Sodium Chloride 2% - Propylene Glycol 2.5% 3.6% 3.0% 15 PHOSPHATES Sodium Tripolyphosphate 0.5% 1.6% 1.0% Calcium Phosphate 0.25% 2.6% 1.05% Sodium Glycerophosphate 0.25% 0.5% Sodium Biphosphate 0.5% - FLAVOURINGS Monosodium Glutamate 3% 3.0% 20 FATS Corn Oil - 3.1% - Animal Fat 1% - ADDITIVES Bran - 2% 1.0% Choline Chloride 0.5% 0.8% Vitamin Premix 0.5% 0.6% 0.7% 25 Absorbic Acid 1.5% 1.2% Potassium Chloride - 1.6% - pH ADJUSTING AGENT Calcium Carbonate 3% 2.6% 4.0%

Claims (5)

1. A mouldable dog food ingredient comprising: 35% - 84% w/w Starches including some proteinaceous and farinaceous materials in 5 0% - 10% w/w ratio 1:2 Fat 0% - 5% w/w Glycol 15% - 25% w/w Casein 0% - 5% w/w Meat digests 10 0% - 2% w/w Additives 0% - 5% w/w Preservatives 0% - 1.0% w/w Vitamins 0.5% - 8% w/w Phosphate 0% - 5% w/w Flavouring 15 0.5% - 5% w/w CaCO 3 and sufficient water to bring the water content of the ingredient within the range 15 to 20% w/w, most ideally within the range 16 to 18%.

2. A mouldable dog food ingredient as claimed in claim 20 1 in which the ratio of proteinaceous to farinaceous material is 1:1.5.

3. A mouldable dog food ingredient as claimed in claim 1 in which the starches are chosen from: Tapioca 25 Corn Broken rice Wheat flour Potato Rice flour - 16 Corn flour Oat flour Sugar beet. (

4. A mouldable dog food ingredient as claimed in any preceding claim in which the phosphates are chosen from: Monobasic sodium phosphate Monocalcium phosphate Sodium Tripolyphosphate Calcium phosphate Sodium Glycerophosphate Sodium biphosphate and the food flavourings are chosen from: Meat Digest Cheese Powder Chocolate Chlorophyll Honey Vegetable Propylene glycol Monosodium glutamate Sodium chloride.

5. A mouldable dog food ingredient substantially as described herein with reference to and as illustrated in the accompanying examples.