RETORTED PET FOOD IN A FIBRE-BASED CONTAINER

Abstract: A retorted pet food product. The product is a pet food composition packed within a container formed of a laminated material having a fibre-based base layer. The pet food composition is a wet product which has a moisture content above about 40% by weight. The retorting of the pet food product increases its palatability.

Description: Retorted pet food in a fibre-based container Field of the Invention This invention relates to a retorted pet food in a fibre-based container. The invention also relates to a process for improving the palatability of a pet food in a fibre-based container. Background to the Invention Pet foods are commonly classified as wet, semi-moist or dry. Wet pet foods are traditionally available as meat loafs, chunk-type products, and mixtures of meat loafs and chunk-type products. They are usually available in cans and are highly palatable to pets. While cans are an excellent form of container for wet pet foods, they do have some disadvantages. For example, unless they are equipped with an opening system, the pet owner must have a can opener to open the can. However, equipping cans with opening systems increases the cost. Also, many people, especially elderly people, find it difficult prise lose the opening system to use it. Further, sealing problems have occurred with certain opening systems leading to spoilage of the pet food. Also, used cans take up more space in waste disposal systems. Wet pet foods are also available in aseptically filled pouches. These pouches are extremely convenient for consumers because they are easy to open and dispose of. However, the foods in these pouches are not always as palatable to pets as are canned pet foods. Therefore there is a need for pet foods in container systems which are convenient for consumers and where the pet food retains good palatability. Summary of the Invention Accordingly, in one aspect, this invention provides a retorted pet food product, the product comprising a container formed of a laminated material having a fibre-based base layer, and a pet food composition within the container. It is surprisingly found that the retorting of a pet food composition in a container formed of a laminated material having a fibre-based base layer increases the palatability of the pet food composition as compared to non-retorted pet food compositions. In certain cases, the palatability may be better than that of similar pet food compositions which are in cans and which have been retorted. Preferably, the pet food product contains a wet pet food composition which has a moisture content above about 40% by weight; for example about 45% to about 85% by weight. Preferably, at least a portion of the pet food composition is solid or substantially solid. The pet food may be a cat food. It is found that the pet food products are highly palatable to cats. However, the pet food composition may also be a dog food. The pet food composition preferably comprises a gelatinised, solid food composition. For example, the food composition may be in the form of a thermally gelled emulsion or pieces of a thermally gelled matrix. Preferably, the pet food product is retorted to a C 0 value of at least about 100 minutes; for example about 120 minutes to about 180 minutes. The pet food is preferably retorted to a F 0 value of about 15 minutes to about 30 minutes. In a further aspect, this invention provides a retorted pet food product the product comprising a container formed of a laminated material having a fibre- based base layer, and a pet food composition within the container, the pet food product being produced by filling pet food composition into the container, sealing the container, and retorting the container to a C 0 value of at least about 100 minutes. In another aspect, this invention provides a process for improving the palatability of a pet food composition in a container formed of a laminated material having a fibre-based base layer, the process comprising retorting the container to reach a C G value of at least about 100 minutes. The invention also provides a pet food product produced by the process defined above. Detailed Description of the Preferred Embodiments Embodiments of the invention are now described by way of example only. In this specification, the term "F 0 " means the equivalent time in minutes that the product would be held at a reference temperature of 121.1°C to achieve the same level of sterility. Ordinarily, the F 0 value is approximated by the equation:- F 0 = t antilog((T-T ref )/Z) where:- t is the cooking time in minutes, T is the temperature in °C; T ref is l21.1°C; and Z is a value related to a particular organism and is usually approximated as 10°C (which is the value for Clostidium botulinum). The term "C 0 " means the cooking value and is the equivalent time in minutes that the product would be held at a reference temperature of 100°C to achieve the same level of cooking impact on all ingredients. Ordinarily, the C 0 value is approximated by the equation:- C 0 = t a tilogC T-T ref yZ) where:- t is the cooking time in minutes, T is the temperature in °C; T ref is 100°C; and Z is a parameter related to a sugar/Maillard reaction and is usually approximated as 33°C. This invention relates to a retorted pet food product in which a pet food composition is within a container formed of a laminated material having a fibre- based base layer. The pet food composition is found to be highly palatable to pets. The laminated material forming the container comprise at least a base layer and an inner layer. The material may also have an outer layer. The material must be moisture and heat resistant to a degree sufficient such that it is suitable for retorting. The base layer is a fibre-based layer; for example or paper or cardboard layer. The base layer provides the laminated material with mechanical strength and dimensional stability. The inner coating should be constructed of a moisture and heat resistant material. If an outer coating is used, it is preferably constructed of a moisture and heat resistant material. The laminated material may also include one or more barrier layers. The laminated material may also include further layers as desired; for example adhesives, primers, lacquers, and the like. Suitable laminated materials are commercially available. Further, suitable laminated materials are described in US patent 3322318, WO 97/02140, WO 97/02182 and WO 97/02181; the disclosures of which are incorporated by reference. The container may be provided with suitable lines of weakness to enable the container to be torn open. This may be done as is conventional with this type of laminated material. The pet food composition within the container may be any suitable pet food which is solid or includes solid pieces. One suitable composition is a thermally gelled emulsion which sets upon cooling. A gelled meat loaf is an especially preferred example of a thermally gelled emulsion. The thermally gelled emulsion may be prepared by comminuting a suitable meat material to produce a meat batter. The meat material may be any suitable meat source, for example, muscular or skeletal meat, meat by-products, meat meals or a mixture of these sources. The meat source may be of any suitable animal, bird or fish. The exact composition of the meat source may be selected according to cost and the desired flavour. Suitable gelling agents, for example starches and gums such as kappa-carrageenan, locust bean gum, guar gum, and xanthan gum may be added to the meat batter. Usually no more than about 1% by weight of gum is needed. Additional ingredients such as sugars, salts, spices, seasonings, flavouring agents, minerals, vitamins, and the like may also be added to the meat batter. The amount of additional ingredients used is preferably such that they make up about 0.25% to about 3% by weight of the meat batter. Water may also be added the meat batter to provide from about 70% to about 85% by weight of moisture. If sufficient moisture is present in the meat material, water need not be added. The meat batter is then heated to a temperature suitable to initiate thermal gelling of the mixture; for example a temperature of about 40°C to about 65°C in a mixer-cooker. Steam may be injected into the meat batter if desired. The heated meat batter may be emulsified if desired. The meat batter is then maintained at a temperature of about 40°C to about 65 °C until needed. After retorting and cooling to room temperature, the meat batter forms a thermally gelled emulsion which is substantially solid or at least holds its form. Another suitable pet food composition may be solid food pieces in gravy or gel. The mixture of solid food pieces in a gravy may be prepared by simply mixing together solid pieces of meat or other material, or both, and a gravy. The meat material may be any suitable meat source as described above. The meat material may be in the form of chunks or may be in the form of flakes. Solid pieces of other materials may also be used; such as rice grains, pasta or noodles, vegetable pieces, and the like. However, it is preferred that the solid food pieces be in the form of pieces of a thermally gelled matrix. The pieces of the thermally gelled matrix may be produced by any suitable procedure, for example the procedures described in US patents 4,781,939, 5,132,137 and 5,567,466 and PCT application WO 97/02760; the disclosures of which are incorporated by reference. In these procedures, a meat material is formed into a meat batter; usually by grinding and then emulsifying blocks of the meat material. Usually a protein source is added to the emulsion to improve emulsion stability and binding. The protein source may be a vegetable or animal protein source; for example plasma, wheat gluten, soy flour, soy protein concentrates, soy protein isolates, egg proteins, whey, casein, etc. If desired or required, fats may be added to the emulsion. If added, the fats may be any suitable animal fats; for example tallow, or may be vegetable fats. Additional ingredients such as sugars, salts, spices, seasonings, flavouring agents, minerals, vitamins, and the like may also be added to the emulsion. Water may also be added to provide from about 45% to 80% by weight moisture in the emulsion. If sufficient moisture is present in the meat material, water need not be added. The emulsion may then be processed in suitable equipment such as an emulsion mill or an extruder to form pieces or chunks. If an extruder is used, the emulsion may be forced through an orifice to provide the emulsion with a desired shape; for example of oval, square or rectangular cross-section. The extrudate may then be cooked in a suitable continuous cooking system; for example a tunnel oven using hot air, steam, mixtures of hot air and steam, or microwaves as the heating medium. The core temperature ofthe extrudate is raised such that the extrudate undergoes thermal gelling. For example, the core temperature may be raised to at least about 80°C; for example about 85°C to about 95°C. The gelled extrudate may then be cut into pieces and the pieces cooled to provide pieces of a thermally gelled matrix. The pieces may be subjected to flaking if desired. The cooling may be carried out by spraying water on the pieces. Alternatively, other cooling media may be used. If a gravy is used with the solid food pieces, it may be produced from water, one or more starch or gums, and suitable flavouring agents. The gravy preferably comprises about 20% to about 80% by weight of the mixture of solid pieces and gravy. Suitable gums are kappa-carrageenan, locust bean gum, guar gum and xanthan gum. If a gel is used with the solid food pieces, it may be produced from a suitable gelling agent, water and suitable flavouring agents. The gel preferably comprises about 20% to about 80% by weight of the mixture of solid pieces and gravy. Suitable gelling agents are proteins such as gelatine; gums such as alginates, kappa-carrageenan, locust bean gum, guar gum and xanthan gum, and the like. The gel or aspic may be prepared as is conventional. Another suitable pet food composition may be solid food pieces in a thermally gelled emulsion. The thermally gelled emulsion may be prepared as described above. The solid food pieces may be pieces of a thermally gelled matrix, meat peices, vegetable pieces, combinations of these pieces, and the like. The pieces of the thermally gelled matrix may be produced as described above. As a further alternative, combinations of thermally gelled emulsions and solid food pieces in gravy or gel, may be used. Suitable combinations are described in WO 98/05218 and WO 98/05219; the disclosures of which are incorporated by reference. The containers are formed and the pet food composition is filled into the containers as is conventional with this type of container or in accordance with instructions provided by the manufacturer of the filling apparatus. Further, a suitable forming and filling procedure is described in WO 97/02182. The containers are sealed as part of the filling procedure. The sealed containers are then subjected to retorting; usually in an autoclave. A suitable retorting procedure is described in WO 98/16431; the disclosure of which is incorporated by reference. In general, the sealed containers are heated to a temperature in the range of about 70°C to about 128°C. The retorting time, including the time to raise the temperature and lower the temperature, should be sufficient to provide the contents of the container with a C 0 value of at least about 100 minutes. Preferably, the retorting time should be sufficient to provide the contents of the container with a C 0 value of about 120 minutes to about 180 minutes; for example about 150 minutes. A retort time of about 120 minutes to about 150 minutes should be sufficient in most cases. It is found that the palatability of the pet food composition is related to the C 0 value. As the C 0 value increases to the region of 100 minutes and above, the palatability of the pet food composition increases. In fact, for certain pet food compositions, the palatability in a fibre-based container may be better than that of similar pet food compositions in cans. Further, the retorting time should be sufficient to sterilise the contents of the container; for example to a F 0 value of at least about 15 minutes. Preferably the F 0 value is about 20 minutes to about 30 minutes. The pet food product is preferably cooled in two stages to terminate the retorting. In a first stage, the pet food product may be cooled with air or a suitable dry gas. Thereafter, in a second stage, the pet food may be cooled with water or other liquid in the normal manner. A suitable procedure is described in WO 98/16431. It will be appreciated that numerous modifications may be made to the embodiments described above without departing from the scope of the invention as set out in the claims. For example, it is not necessary for the entire container to be made of the laminated material. If desired, certain portions of the container, for example the lid, may be made from metal sheets. Specific examples of the invention are described for further illustration. Example 1 A chunk in jelly pet food composition is filled into containers made of laminated material. The laminated material comprises a polypropylene inner layer, an aluminium barrier layer, a cardboard base layer and a polypropylene outer layer. The laminated material is obtained from Tetra Pak International AB of Sweden. The forming, filling and retorting line is also obtained from Tetra Pak International AB. The containers are formed, filled and sealed in accordance with the manufacturer's instructions. The containers are then subjected to a retort reaching about 128°C for a time of about 2 hours. The C 0 value is 150 minutes and the F 0 value is 25 minutes. During cooling, the containers are first cooled with air to a core temperature of about 90°C and then cooled with water. The pet food product is labelled as sample 1. For comparison, the chunk in jelly product is aseptically filled into containers of the same laminated material. The containers are formed, filled and sealed in accordance with the manufacturer's instructions. The product is not retorted. The pet food product is labelled as sample A. Similarly for comparison, the chunk in jelly product is filled into cans in the normal manner. The cans are retorted to a C 0 value of 100 minutes and a F c value of 40 minutes. The pet food product is labelled as sample B. The pet food products are then fed to a panel of cats. The cats have free access to three bowls; one containing food from Sample 1, one containing food from Sample A, and one containing food from Sample B. The amount of each food each cat consumes is monitored. The cats consume substantially equal amounts of food from Samples 1 and B. However, the cats consume significantly less food from Sample A. Therefore retorting of the pet food product in containers made of laminated material increases palatability. Example 2 Example 1 is repeated except mat the containers and cans are filled with a meat loaf. The retorted food product in containers made of laminated material is labelled as Sample 2. The cats consume significantly more of food from Sample 2 than the canned product and the aseptically filled product. The retorting of the pet food product in containers made of laminated material increases palatability. Example 3 Cats are fed food from Samples 1 and B of example 1 after 2 days, 15 days, 3 months, 6 months and 1 year's storage. The cats consume substantially equal amounts of food from Samples 1 and B at each time point. Therefore the food of Sample 1 stores as well as food in a can.

Claims: Claims 1. A retorted pet food product, the product comprising a container formed of a laminated material having a fibre-based base layer, and a pet food composition within the container. 2. A retorted pet food product, the product comprising a container formed of a laminated material having a fibre-based base layer, and a pet food composition within the container, the pet food product being produced by filling pet food composition into the container, sealing the container, and retorting the container to a C 0 value of at least about 100 minutes. 3. A retorted pet food product according to claim 1 or claim 2 in which the pet food composition has a moisture content of about 40% to about 85% by weight. 4. A retorted pet food product according to any of claims 1 to 3 in which the pet food composition comprises a gelatinised, solid food composition. 5. A retorted pet food product according to claim 5 in which the gelatinised, solid food composition is a thermally gelled emulsion. 6. A retorted pet food product according to claim 5 in which the gelatinised, solid food composition is in the form of pieces of a thermally gelled matrix. 7. A retorted pet food product according to any of claims 1 to 6 in which the pet food product is retorted to a C 0 value of about 120 minutes to about 180 minutes. 8. A retorted pet food product according to any of claims 1 to 7 in which the pet food product is retorted to a F 0 value of about 15 minutes to about 30 minutes. 9. A process for improving the palatability of a pet food composition in a container formed of a laminated material having a fibre-based base layer, the process comprising retorting the container to reach a C 0 value of at least about 100 minutes. 10. A process according to any of claims 1 to 9 in which the pet food product is retorted to a C 0 value of about 120 minutes to about 180 minutes .

Inventors: DUPONT CHRISTOPHE, GASSER RUPERT JOSEF, DUPONT, CHRISTOPHE, GASSER, RUPERT, JOSEF
Applicants: DUPONT CHRISTOPHE, GASSER RUPERT JOSEF, NESTLE SA, DUPONT, CHRISTOPHE, GASSER, RUPERT, JOSEF, SOCIETE DES PRODUITS NESTLE S.A.
Application year: 1999
Main classification: A23K1
IPC codes: A23K1, A23K3