IES990688A2 - A process for the preparation of pet food - Google Patents

Abstract

Grinding (12) fresh and frozen protein source material to form a ground protein source, mixing (21) the ground protein source with dry ingredients and water to form a mixture, emulsifying (26) the mixture by cutting in a microcutter under vacuum, extruding (32) the emulsion under vacuum to form a uniform extrudate, conditioning the extrudate by conveying into a steam tunnel (33) and applying turbulent steam to the extrudate, cutting (34) the conditioned extrudate into discrete chunks of predetermined length, delivering a predetermined amount of discrete chunks into cans, delivering a predetermined amount of filler into cans (42) and sealing (44) and retorting (48) the cans to cook the pet food. <Figure 1>

Description

The present invention relates to a process for the preparation of pet food and particularly to moist pet food produced by emulsion and extrusion and more particularly to the process of making the pet food.

Within the class of pet foods, there are three basic sub-divisions:--Ί Ο’' · *»· ·. Ί3 co m T ··*$ Λ ϋ Ti n • 0 .--0 2: co ΓΠ m co o δ 2$ —-n.„ (1) dry pet food containing up to 15% moisture, (2) semi-moist pet food usually containing about 15% to 50% moisture, and ?=> 22 N —ι ί C-) Γ “-Μ d ύ s, i c' K? (3) moist pet foods containing above 50% moisture.

The moisture content of the product is determined by the water content of the ingredients and the water combined with various ingredients which make the final product. In general, dry pet foods are more stable primarily because of the low moisture content which does not support microbiological growth. The moist pet foods have a high nutritional and caloric value and have a higher degree of palatability due to their meat-like texture, consistency and aroma. However, the elevated moisture content of such products provides ideal conditions during the process of manufacture for the growth of such organisms as yeast, moulds and bacteria.

The moisture content of the product functions to permit the product to be readily deformed by pressure and retain the shape imparted to it by such pressure deformation. The water content of the product may be provided by the addition of water, although water is inherent in the components of the mixture such as meat or meat by-products or protein. The water content of the final product may contain 70% moisture.

It is therefore necessary to take precautions, considering the high moisture content of -2IE990688 the food, to ensure that microbiological decomposition does not occur particularly during the stages of manufacture of the product Should microbiological growth occur, the surviving organisms can be destroyed by a sterilisation or pasteurisation process. However, the organisms could taint the product resulting in the production of offodours and effecting the taste and can also cause the production of obnoxious gas pockets within the product. Then the desirable nutritional characteristics of the moist pet food would be defeated by its poor payability. Therefore, there is a need to minimise microbiological growth during the production process.

Moist pet foods are very nutritious for the animal because of the high meat content. However, it is expensive to include high quality and quantity meat in a pet food. Many attempts have been made in the past to assimilate moist meat chunks, and thus maintaining the nutritional requirements of the animal whilst maintaining low cost Previously the meat protein was replaced by soya protein. This resulted in chunks that did not have the appearance of meat, and in the soya protein becoming lumpy following heating to cook. Animals additionally find soya protein difficult to digest with flatulence being a major side effect. Sodium alginate is another substance that has been used to replace meat proteins. This also is not ideal. Sodium alginate contains calcium which when displaced is unpalatable to the animal. It is also very difficult to make a pet food that contains the complete nutritional requirements for a pet from the formulations with the meat protein replaced.

WO 9805224 is directed to a process for the production of a room temperature, shelf stable, cased meat product for animal and human consumption. A mixed meat emulsion is forced into a plastic casing and cooked at 121°C under pressure. The proteins in the meat coagulate at the high temperature. The plastic casing prevents the meat product from loosing moisture. However, in the absence of the covering the meat product would become hard. US 5792504 is directed to a process for the production of a formulated emulsion product which has a meat-like appearance for use as a pet food. The protein source is emulsified and alkali is added to raise the pH to above 8. The emulsion is then rapidly heated above 100°C causing the protein in the heated emulsion to partially coagulate. The problem with raising the emulsion temperature to above 100°C is that when emulsified protein is heated too high, the -3IE990688 emulsion becomes hard and crumbly, no longer resembling fresh meat pieces.

It is an object of the present invention to provide a moist pet food of desirable nutritional characteristics, which is microbiologically stable without the addition of excessive antimicrobial agents for product sterility. It is an object of the invention to provide an environment during the process for the preparation of the pet food such that microbiological growth is minimised.

It is an additional object of the present invention to provide a moist pet food with 10 chunks that simulate fresh pieces, have higher palatability, nutritional quality and digestibility.

Statements of Invention This invention relates to a process for the preparation of a moist pet food comprising chunks, fillers and often gravy often containing a protein source of at least 40% w/w of the chunks poultry and 5 -10% w/w of the chunks meat materials.

The poultry and meat materials are added fresh or frozen or a combination of both to form a starting product within a period of 10 to 50 minutes. The poultry and meat materials are initially pre-broken into smaller more manageable pieces. The advantages of mixing fresh and frozen poultry and meat materials in the optimum ratio ensures a minimal temperature rise in the pre-broken starting product.

The starting product is then ground at a controlled rate for a period of 10 to 50 minutes to form a ground protein source, such that the temperature of the ground protein source is in the range of -8 to +8°C. The advantage of grinding at a controlled rate is that the resultant ground protein source is ground gently, thus minimising shear stress and thereby minimising temperature rise.

The ground protein source is weighed within a period of 10 to 50 minutes and pumped to a double shaft mixer. 0.01 - 40% w/w of the chunks dry ingredients are weighed within a period of 10 to 50 IE990688 -4minutes and transferred to a holding hopper above the double shaft mixer containing the ground protein source. The dry ingredients are chosen from one or more of the following and subsequently added to the double shaft mixer up to 20% w/w farinaceous starch; 0.01 to 4% w/w salt; up to 2% w/w colouring agent; 0.01 to 3.5% w/w additional protein; up to 3% w/w additional fats; up to 3% w/w flavouring agent; and up to 3% w/w vitamins and minerals The selection of dry ingredients enables the production of a moist pet food that resembles fresh meat pieces, but with minimum meat content The salts are added at sufficiently high ionic strength to enable moisture absorption and therefore achieve swelling of the myofibrillar proteins of the muscle. The advantage of adding additional protein is that it overcomes the problem of the presence of low myofibrillar protein in the meat added. The further addition of vitamins and minerals helps to enhance the nutritional requirement of the pet food ensuring that an animal’s complete diet can be obtained from the food.

Water is then added to the double shaft mixer until a water content in the range of 60 to 90% w/w of the chunks is achieved. The addition of water to achieve a water content in this range in combination with the dry ingredients, poultry and meat materials enables the production of a moist pet food resembling the texture and strength of fresh meat pieces. The ground protein source, dry ingredients and water are then mixed under vacuum, over a period of 10 to 50 minutes, at a controlled rate to form a mixture. Steam is optionally injected into the double shaft mixer, containing the mixture, to maintain the temperature in the range of-5 to 10°C. The protein binds the moisture in combination with the salts to form a good quality meat-like moist pet food. Unless the correct combination of ingredients are chosen, it is difficult to get a consistency resembling meat. The amount of water is added according to the nature and quality of the poultry and meat materials. The moisture content endogenous in poultry material ranges form 55 to 80% w/w of the chunks and this determines the -5ΙΕ99068» amount of water that needs to be added.

The mixture is subsequently emulsified, by grinding the mixture at a controlled rate for a period of 10 to 50 minutes. The formed emulsion ranges in temperature from 0 to 25°C. It is important that the temperature of the emulsion does not exceed 25°C for several reasons. If the temperature of the emulsion gets too hot, the emulsion breaks down. The added poultry and meat materials have a normal bacterial content. By keeping the temperature below 25°C, a system is created that minimises bacterial growth. This process for preparing moist pet food has the advantage of minimising microbial proliferation by strictly controlling the temperature of the ingredients and the emulsifying rate. The mixture is then extruded in a split head extruder to form two uniform extrudates. The moisture content of the mixture permits the extrudate to be readily deformed by pressure and to retain the shape imparted to it by such pressure deformation.

The extrudate is then conditioned and pasteurised for a period of 70 to 150 seconds by applying turbulent steam to the extrudate such that the core temperature of the extrudate is heated between 75 and 95°C. The advantage of conditioning the extrudate in the steam tunnel is that the core temperature of the extrudate enables the heat setting of the proteins, while minimising the hardness of the extrudate. Over heating effects the texture of the extrudate by making it too hard, crumbly and liable to fracture easily. Thus, the resultant extrudate has the look and feel of a high meat content moist pet food.

The extrudate is cut into discrete chunks of predetermined length and with or without additional filler are added simultaneously in a predetermined amount into cans. The additional filler can include pasta and/or vegetables. The further addition of additional filler into the cans increases the nutritional content and organoleptic quality of the resultant moist pet food.

Depending on the product required gravy may then be added to fill the cans, at a temperature of 10 to 90°C under vacuum. The gravy at this temperature range has a viscosity such that it is easily poured. As the temperature decreases the viscosity increases due to the nature of the ingredients. The gravy is added quickly to minimise -6IE990688 bacterial proliferation.

The cans are sealed and retorted for a period up to 120 minutes to cook the pet food. The advantage of this is that if any microbial infection has occurred, by retorting for this period of time ensures that they do not survive and the resultant product is commercially sterile. However if microbial infestation has occurred, despite the fact that they have been subsequently destroyed, their original presence may have resulted in the production of off odours, making the pet food unpalatable for the animal. Thus the controls inherent in this process to minimise bacterial proliferation are very important to avoid spoilage. Destruction of any microbial infestation ensures a safe product but is not the answer to the problem.

Thus, the various steps of the process are controlled such that the overall time from the initial pre-breaking and weighing of the poultry and meat material, to the initiation of the step of retorting the cans does not exceed 140 minutes. The speed of the process and the tight control of the temperature leads to minimal microbial infection and rancidity. The ingredients are specifically chosen to assume a nutritionally high quality moist pet food. The ingredients interact and absorb sufficient moisture to provide a moist pet food resembling fresh meat pieces.

In one embodiment of the invention the time of the process from pre-breaking the poultry and meat materials to the initiation of the retorting step does not exceed 100 minutes.

Ideally the temperature of the poultry and meat materials added fresh does not exceed 10°C and the temperature of the poultry and meat materials added frozen exceeds 14°C. By combining fresh and frozen poultry and meat materials, at specific temperature ranges, it is possible to control the temperature of the resultant products.

In a preferred embodiment of the invention the temperature of the ground protein source is approximately 2°C and the temperature of the emulsion is approximately 18°C. By controlling the temperature of the initial ingredients and the speed of the process it is possible to control the temperature of the resultant product at each stage.

IE990688 -7In one embodiment of the invention the core temperature of the extrudate is between 85 and 88°C. At this temperature the proteins set, while forming a stable extrudate.

In another embodiment of the invention, the gravy is added at a temperature of 30°C.

In a preferred embodiment of the invention, the poultry material is selected from any part of the animal. In another embodiment of the invention the meat materials are selected from the group comprising poultry, domestic and wild, mammals, shell fish and fish.

In another embodiment, the additional protein is selected from the group comprising meat, meat by-products, coaguable and non-coaguable proteins. The further addition of additional protein overcomes the problem of the low levels of myofibrillar proteins in the poultry and meat materials.

In another embodiment the gravy can be selected from the group comprising carrageenan, locust bean gum, guar gum, xanthan gum, cassia, starch, agar, gellan and pectin.

In a further embodiment additional fillers are selected from the group comprising pasta and vegetables.

Detailed Description of the Invention The invention will be more clearly understood from the following description given by way of the accompanying layout drawing and various examples.

Referring to Figure 1, there is illustrated a layout of the plant for carrying out most of the process for carrying out the present invention. In Figures 1 and 2, there is provided a lifting bay storage area indicated generally by the reference numeral 1 for fresh and frozen raw material bins 2. A bin lifter 3 is mounted beside a hopper 4 above a screw conveyor 5 which feeds a metal detector 6 above a conveyor belt 7 feeding a prebreaker 8 above a pump 9. The conveyor 7 is also fed by a further pallet lifter 10. The pump 9 is connected by a pipe 11 to a grinder 12 which feeds by a conveyor 13 a ΙΕ990&Β» -8hopper 14 above a weigh screw conveyor 15 which is simply a screw conveyor mounted on load cells. An excess feed hopper 16 is mounted beneath the conveyor 13 remote from the feed hopper 14 as is evident in Figures 1 and 3. The pipe 11 has connected thereto a compressed air source (not shown) as well as heating facilities. The grinder 12 is simply a mincer having a double knife set with a fine hole plate in the order of 5mm diameter. The screw weigh conveyor 15 feeds a cross conveyor 20 which in tum feeds a double shaft mixer 21 having a vacuum source (not shown) and steam injector.

A dry ingredient storage hopper 22 feeds the double shaft mixer 21 through an overhead vacuum pipe 23. The mixer 21, in tum, feeds a pump 25 which feeds a final emulsifier 26 through a pipe 27. The final emulsifier 26 is a micro-cutter equipped with a double knife set and in tum discharges through a pipe 28 into buffer tanks 29. The buffer tanks 29 deliver through piping 30 and a pump 31 to an extruder 32 feeding a steam tunnel 33 which in tum is connected to a cutter 34. The extruder 32 is a split head extruder with two extruder heads with a closed pressure hopper for the in-feed of the emulsified mixture. The extruder 32 is sited at the inlet to the steam tunnel 33 which comprises a hood mounted over a conveyor belt. The top of the hood of the steam tunnel is set down close to the extrudate travelling thereon to ensure correct turbulent flow of steam. In Figures 1 and 4, the cutter 34 comprises a series of cutter blades and slitters for both longitudinal and transverse cutting of extrudate.

The cutter 34 is connected by conveyors 35,36 and 37 to a rotary pocket filler 40. The pocket filler 40 is connected by a conveyor 41 to a vacuum filling machine 42 for gravy filling which delivers through a seamer 44 to a discharge conveyor 45 to a can washer 46 through a filled can conveyor 47 to cooking retorts 48. A tank 52 feeds through a mixer 51 to a storage tank 50 which in turns feeds through a pipe 53 to the vacuum filling machine 42.

In operation, fresh material at an optimum temperature of 1 to 8°C is carried out in the raw material bins 1 and placed on the bin lifter 3 where it is raised and tipped into the hopper 4. Then it is delivered into the screw conveyor 5 to the metal detector 6 which will reject fresh material containing metal in the conventional manner. The fresh material is then delivered to the conveyor 7, to the pre-breaker 8 of the pump 9 and IE990688 -9then through the pipe 11 to the grinder 12. Similarly, frozen material at an optimum temperature of -14 to -1°C usually on pallets will be placed on the pallet lifter 10 and raised up onto the conveyor 7 where it will be delivered under the metal detector 6. In the case of metal being discovered in the frozen material the conveyor 7 will stop and the contaminated frozen material will be removed. Similar rejection occurs of fresh material containing metal. After going through the metal detector 6 the frozen material is delivered on the conveyor 7, to the pre-breaker where the material is broken and then again delivered by the pump 9 to the grinder 12. As the material is being ground and all the material from the grinder 12 is placed in the mixer 21 it will have a temperature in the range of -2 to +5°C depending on the amount of frozen material and/or chilling of the material which has to take place to achieve this after all the ingredients are added. Pre-breaking, weighing and grinding the fresh and frozen material takes from 10 to 50 minutes, 1 for each individual step of the process. The grinder 12 will pre-comminute the raw material down to approximately 5mm size. The ground material is then delivered through the conveyor 13 to the hopper 14 onto the weigh screw conveyor 15 which will then deliver it to the conveyor 20 and then into the mixer 21. When sufficient of the particular material has been delivered to the weigh screw conveyor 15, air is then introduced into the pipe 11 at the outlet of the pump 9 and all surplus raw material will be delivered onto the cross conveyor 13 which will be reversed to return any surplus material for later reuse through 16. For example, if there were four materials in a particular recipe, one material at a time will be introduced and weighed on the weigh conveyor 15. It is also possible to pre-weigh all materials and run through the system using weigh screw conveyor 15 to control total final batch weight. When the full amount of material has been delivered into the weigh screw conveyor 15 the mixer 21 is loaded via conveyor 20 and water and dry ingredients and added to the mixer. Dry ingredients are delivered by being blown through the pipe 23 to the mixer 21. The water is taken from a local well, so the temperature of the water is seasonally dependent. A vacuum is formed on the mixer 21 and the mixing is conducted in such a way as to ensure that the temperature of the pre-emulsified mixture and the dry ingredients does not exceed 15°C this takes from 10 to 40 minutes. The mixture is then delivered out of the mixer 25 through the pipe 27 to the emulsifier 26. The rate of feed to the emulsifier 26 is such as to ensure that the temperature of the emulsion does not exceed 25°C and this process takes from 5 to 20 minutes. Thus, depending on the raw material, the rate of feed can be changed. ¢990688 -10After emulsification, the material is held in the two buffer tanks 29 until it is delivered to the split head extruder 32.

The emulsion in the buffer tanks 29 is transported at controlled pressure by the pump 31 to the extruder 32 which will ensure a forced in-feed into the extruder 32. The material will be extruded either in the form of a continuous slab of extrudate onto the conveyor forming part of the steam tunnel 33 or in the form of discrete strips and this process takes from 70 to 150 seconds. The extrudate when extruded will have at least 60% water content and on delivery to the steam tunnel 33 will be conditioned by applying turbulent steam such that the core temperature of the extrudate is heated to greater than 75°C. Generally, the extrudate will be heated to at least 80°C and optionally 85 to 88°C. The cutter unit 34 will then cut the extrudate as required. If the extrudate has been extruded in a continuous slab it will be necessary first to slit the extrudate longitudinally and then to chop the extrudate transversely. The extrudate can be chopped into regular lumps or irregular chunks or any other particular shape required. The extrudate which has now been conditioned is then delivered to the pocket filler 40 where open cans are fed into the machine and the chunks are metered into the cans other. Other ingredients such as vegetables, pasta and meats etc. can be added also. The chunk-filled cans are then passed to the vacuum filler 42 through the conveyor 41. The filling machine is designed to fill free-flowing and high viscosity liquids at high speeds into cans, jars and rigid containers. The necessary filler is delivered through the pipe 53 to the vacuum filler 42. When the filling phase has been completed the containers are discharged to the seamer 44 where lids are placed in position in the conventional manner and the cans are delivered to the conveyor 45 and washer 46 to conveyors 47 to conventional retorts 48 where the final cooking takes place for up to 180 minutes. The entire process does not take longer than 260 minutes. The process can be described as continuous, however, lay times do exist for critical additives for example the poultry and meat materials. Certain of the ingredients are stored in hoppers. When they cannot be delivered immediately. However, the process is never stopped and left overnight as the key objective of the process is controlling time and temperature to minimise spoilage.

The following tables list some of the materials used. - 11 IE990688 TABLE 1 Farinaceous starch can be selected from the group comprising: Wheat flour Oat flour Rice flour Com flour Ground wheat Maize TABLE 2 Additional protein can be selected from the group comprising: Soya bean Oil seed Rape seed Wheat gluten Com gluten Blood plasma TABLE 3 Additional fats can be selected from the group comprising: Sunflower oil Flax oil Primrose oil Soya oil Rape seed oil Fish oil Omega-3 containing oil Vegetable oil -12IE990688 TABLE 4 Salt can be selected from the group comprising: Sodium chloride Polyphosphate Tri polyphosphate TABLE 5 Colouring agent can be selected from the group comprising: Caramel Titanium oxide Red oxide Brown oxide Any EEC permitted colouring agent TABLE 6 Vitamins and minerals can be selected from the group comprising: Vitamin A; Vitamin B1; Vitamin B2; Vitamin B6; Vitamin B12; Vitamin D3; Vitamin E; Vitamin K; Vitamin 92; Nicotinic acid; Calcium Pantothenate; Potassium iodide; IE990688 -13Pantothenate acid; Selenium; Alpha tocopherol; Thiamine; Biotin; Iodine; Iron; Zinc; Zincoxide; Copper; Manganese; Calcium; Sodium; Protein; Fibre; Choline Chloride; Rovimix B1; BHT; Butylated L Leucine Taurine; Ash; Oil; Acid insoluble ash; Category 2 Category 14 Carriers (hyprofod grade) Limestone Irish TABLE 7 Gravy can be selected from the group comprising: Carrageenan Locust bean gum IE990688 -14Guar gum Xanthan gum Cassia Starch Gellan Agar Pectin TABLE 8 Poultry material can be selected from the group comprising: Carcass Necks Drumsticks Viscarae Feet Skin Flesh TABLE 9 Meat materials can be selected from the group comprising: Duck Liver Heart Kidneys Rabbit Beef Pork Tripe Fish Turkey Lamb IE990688 -15Tuna Salmon Plaice Mackeral Prawn White fish Cod Haddock Crab meat Veal Venison Ham Game Trout Bacon Herring Referring to the examples, examples 1 to 3 include three different formulations to make chunks simulating fresh meat pieces, made according to the above process.

The process involves finely mincing fresh and frozen meat materials in the optimum ratio to ensure minimal temperature increase. Dry ingredients and water are added to the mixture and the mixture is subsequently vacuumed.

The mixture is emulsified ensuring that the temperature does not exceed 20°C as this can result in emulsion breakdown. The mixture is pumped through the extruder into the steam tunnel, where a degree of cooking is carried out and the core temperature of the extrudate reaches between 80 and 92°C to maximize the heat setting of the proteins.

The extrudate is cut into chunks, which are conveyed to the pocket filler. The chunks and gravy are filled separately in stages. The gravy is filled using the vacuum filler and fills the cans prior to the cans being sealed and retorted.

The entire process, up to sealing and retorting the cans does not take more than IE990688 -16140 minute.

EXAMPLE 1 Product: Chunks in Gravy Variety: Chicken INGREDIENT % RECIPE W/W Chicken 65.0000 Meat materials 7.0000 Gluten dry 1.6317 Cereals dry 6.9958 Vitamins and minerals dry 0.3512 Salt dry 0.9918 Colouring agent dry 0.8912 Water 17.1383 TOTALS 100.0000 EXAMPLE 2 Product: Chunks in Gravy Variety: Chicken INGREDIENT % RECIPE W/W Chicken 79.2800 Meat materials 7.4826 Salt dry 0.8921 Vitamins and minerals dry 0.6312 Colouring agent dry 0.5233 Flavouring agent 0.6212 Water 10.5642 TOTALS 100.0000 -17IE990688 EXAMPLE 3 Product: Chunks in Gravy Variety: Chicken INGREDIENT % RECIPE Chicken 48.7109 Pork 13.2145 Meat materials 7.1264 Salt dry 1.5212 10 Cereal dry 13.1264 Colouring agent dry 0.5212 Vitamins and minerals dry 0.3716 Water 15.4078 15 TOTALS 100.0000 In the specification the terms “comprise, comprises, comprised and comprising” or any variation thereof and the terms “include, includes, included and including or any 0 variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

The invention is not limited to the embodiment hereinbefore described, but may be varied in both construction and detail.

Claims (5)

1. A process for the preparation of a moist pet food comprising chunks and fillers, the chunks containing a protein source of poultry and meat materials comprising the steps of initially preparing the chunks by: pre-breaking, then grinding fresh and frozen protein source to form a ground protein source, such that the temperature of the ground protein source does not exceed 8°C; mixing the ground protein source with dry ingredients and water to form a mixture, having a water content of at least 60%, such that the temperature of the mixture does not exceed 8°C; emulsifying the mixture by cutting under vacuum such that the temperature of the mixture does not exceed 25°C; extruding the emulsion in an extruder to form an extrudate; conditioning the extrudate by applying turbulent steam to the extrudate such that the core temperature of the extrudate is heated to greater than 75°C; cutting the conditioned extrudate into discrete chunks of predetermined length; and then carrying out the subsequent steps of filling a predetermined amount of additional filler and discrete chunks simultaneously into cans; and sealing and retorting the cans to cook the pet food.

2. A process for the production of a moist pet food as claimed in claim 1, in which the dry ingredients are selected from the group:farinaceous starch; -19IE990688 salt; colouring agent; additional protein; additional fats; 5 flavouring agent; and vitamins and minerals.

3. A process for the production of a moist pet food as claimed in claims 1 or 2, in which the poultry material is selected from any part of the animal. --

4. -.-A-process-for-the-productionof-a moist pet food as claimedHn^any-preceding claim in which gravy is added subsequent to the placing of additional filler and discrete chunks into the cans to fill the cans, the gravy being added under vacuum at a temperature between 10 and 90°C.

5. A process for the preparation of a moist pet food substantially as hereinbefore described with reference to the accompanying drawings, tables and/or examples.