FOOD PRODUCT

Abstract: A sheet of proteinaceous product is produced by comminuting heat-coagulable meat without substantially heat-coagulating the meat, and applying a layer of the comminuted (but still heat-coagulable) meat to a heated roller, or other suitable surface. The heat coagulates the meat to form a sheet, which can then be removed for example by a doctor blade. Under appropriate conditions, a ripple effect may be formed. The sheet can be folded and subsequently processed, for example into chunks for use in petfood.

Description: FOOD PRODUCT This invention relates to proteinaceous food products, which may be suitable for use either in human food or in an animal food such as petfood. Various processes for preparing meat analogues from generally vegetable protein sources have been proposed in the past. US-A-2682466, US-A-2802737, US-A-2830902 and US-A-3142571 are examples of proposals for preparing meat analogues from such protein sources as soy bean isolate and peanut protein isolate. Another example is GB-A-1418778 , which discloses the preparation of a meat analogue starting from a dry mix of proteins, starches and/or gums. All of the above processes may be regarded as examples of meat analogue generation. Roll-refining is a process which is known for producing proteinaceous food products and comprises passing material between a pair of oppositely rotating rollers. GB-A-1432278 describes the roll-refining largely of non-meat proteins, although one of its examples, instead of starting with soya protein or casein, begins with "ground meat", soya protein, water and other additives and another of its examples begins with "ground meat", water, casein rennet and other additives. For the food-stuff manufacturer, who has a choice between either meat protein or non-meat protein sources, it would be preferable in many instances to use meat proteins so that an all-meat product can be prepared. Roll-refining has sucessfully been applied to raw proteins of vegetable origin, and it has been desirable to apply the same technology to meat proteins. GB-A-2198623 discloses the roll-refining of fish protein. However, when attempts were made to apply the roll-refining technology to proteins from the higher animals (mammals and birds) , the process has been found to be unworkable since it has generally been found that it is not possible to form a sheet of proteinaceous product from raw mammalian or avian meat unless substantial amounts of additives, such as binding materials are mixed with the meat prior to the process for forming the proteinaceous sheet. Where untreated mammalian or avian meat with no additives has been used, a cohesive sheet is not formed. Sheet products are particularly useful as they may be folded or otherwise used to give a layered structure resembling meat, particularly when cut into chunks. In EP-A-0328349, published on 16th August 1989, it is disclosed that where at least part of the mammalian or avian meat is functionally inert, a cohesive sheet may be formed by roll-refining without the use of additives such as binders being necessary. This was a surprising finding since mammalian and/or avian meat which is entirely functionally active was not found to be capable of forming a cohesive sheet, by roll-refining, and so it was highly unexpected that functionally inert mammalian and/or avian meat would form a cohesive sheet. Further, it is also surprising that the presence of functionally inert proteins appeared to be essential to achieve any form of sheet product. In the method described in EP-A-0328349, a multiplicity of rollers must be used in the roll-refining process, and at least part of the protein must be functionally inert, as defined therein. It would be advantageous to provide a process in which heat-coagulable meat can be formed into a sheet, particularly if this can be achieved without employing a multiplicity of rollers. According to the present invention there is provided a process for producing a sheet of proteinaceous product, the process comprising comminuting a material comprising heat-coagulable meat without substantially heat-coagulating the meat, and applying a layer comprising the comminuted meat which has not substantially lost its heat coagulability to a surface on which the layer is at least partially heat-coagulated to form a sheet, and removing the sheet from the surface. The heat-coagulable meat is preferably present in an amount of from 5% to 100% by weight of the material to be comminuted. Examples of sources of heat coagulable meat include any heat-coagulable protein derivable from an animal (eg mammalian) carcass, such as muscle meat, heart, liver, kidney and fish meat. However it is preferred that the heat-coagulable meat does not comprise fish meat, since fish meat is relatively easily heat coagulated and so requires more strict controls on the conditions of comminution so as not to substantially heat-coagulate the meat during comminution. The material to be comminuted may comprise an edible substance other than heat-coagulable meat. Alternatively or additionally such edible substances may be added to the comminuted material following comminution. Suitable edible substances generally include animal meat or meat by-products such as skin, bone, feather, connective tissue, treated animal carcass products such as pork skin and greaves, and powdered meat meal. The edible substance may comprise "functionally inert protein" as defined and exemplified in EP-A-0328349. Other suitable edible substances may be of a plant source, such as gluten, soya, cereals, pulses, gums and may include vitamins, minerals, oils and/or fats. Although it has been found that while heat-coagulable meats which have not been sufficiently comminuted do not form a sheet when a layer thereof is applied to a surface and at least partially heat-coagulated, it has now surprisingly been found that when the heat-coagulated meat has been comminuted sufficiently, it can form a sheet under such conditions. Without wishing to be bound by theory, this is thought to be due to the size reduction causing increased release and availability of proteins which are heat-coagulable after comminution. The maximum average particle thickness may generally be 3mm, while the particles may be as small as is conveniently practical, but will usually be larger than 10 micrometres. There are believed to be no theoretical limitations on how small the particles may be, and generally, the smaller the particle size, the better results will be obtained. However, depending on the apparatus used there are likely to be practical limitations on the size of the comminuted particles. Typically, the average particle size will be in the range from 40 micrometres to 1mm. Any suitable comminution technique may be used provided that it avoids substantially heat-coagulating the meat; that is to say, for example, localised temperature within the material being comminuted should be kept below a temperature at which the heat-coagulable meat would be at least partially heat-coagulated. The conditions under which comminution takes place should be such that the heat-coagulable meat is not substantially heat-coagulated during comminution. For example, it should be ensured that the temperature of the material during the comminution step does not rise so that the heat-coagulable meat is coagulated. The temperature of the material during comminution is suitably not more than 10°C and not less than -20°C and will usually be in the range from 5°C to -5°C typically from 0°C to 4°C. Maintenance of a relatively low temperature may be achieved by comminuting a chilled or frozen material and by using an apparatus which generates low shear during comminution. Suitable apparatus includes size reduction techniques which are well known in the art such as COMITROL (Trade Mark) or a Bowl Chop device, for example a HOBART BOWL CHOPPER (Trade Mark) . A low temperature of the material may be maintained with ice, and/or low temperature liquids such as "carbon dioxide liquid may be added to the material before and/or during comminution. After comminution the meat may be applied as a layer to a suitable forming surface. The layer may be applied to the surface by any convenient means. The layer may be dropped onto the surface by gravity, for example from a reservoir such as a hopper. Pressure may be applied to the material to aid its application to the surface. Where pressure is applied it should be ensured that the pressure does not increase the temperature sufficiently to cause heat-coagulation of the heat-coagulable meat prior to its contact with the surface. Pressure may be applied, for example, by the use of a "fish-tail spreader", enabling the provision of a long, -thin feed, or by the use of a ball-point type of device. The surface to which the layer comprising the comminuted meat is applied may be a solid continuous surface. In some embodiments the surface will comprise a smooth flat sheet. The surface may be a moving surface, for example, a rotating roller, or alternatively may be stationary. Alternatively the surface may be discontinuous, and may, for example, comprise a mesh, or, a multiplicity of beads, such as hot glass beads or marbles. An important characteristic of the present invention is that heat-coagulation to form a sheet largely takes place on the surface, while there is little or no substantial heat-coagulation of the heat-coagulable meat prior to application to the surface. By contrast, in GB-A-2198623 the material has substantially lost its heat-coagulability prior to formation of a sheet on the surface. In EP-A-0328349 at least part of the protein must be functionally inert and is not heat-coagulable. In order to heat-coagulate the layer on the surface to form a sheet, heat must be applied to the layer while on the surface. Preferably, the layer is heat-coagulated by the use of a heated surface and/or the direct application of external heat to the layer, for example, by convection or radiation. The layer should be sufficiently thin so that it coagulates on the surface. The temperature of the layer when the layer is heat- coagulated is preferably in the range from 60 to 80°C where substantially non-fish heat-coagulable meat is used, and in the range 40 to 50°C where substantially heat-coagulable fish meat is used. The temperature of the surface is such as is necessary to achieve these temperatures, and is dependent on the thickness of the layer and the speed with which the layer is applied to and removed from the surface. The layer generally has a thickness in the range from 0.2mm to 2cm, preferably from 0.5 to 2mm. The layer on the surface may in some embodiments be smoothed on the surface. For example where the surface is a main roller, one or more ancilliary smoothing rollers may be positioned around the circumference to smooth the layer on the roller. The ancilliary smoothing rollers optionally may exert shear on the layer on the roller. The sheet of food product has at least one dimension and preferably two dimensions of at least 3cm, preferably at least 10cm, most preferably at leat 100cm or lm or more in length. The protein content of the sheet is generally in the range from 5% to 50% by weight, more typically in the range from 10 to 40% by weight. The balance will largely comprise water. The water content is generally in the range from 30 to 95% by weight, and preferably from 50 to 90% by weight, more preferably 75 to 85% by weight. The sheet may be removed from the surface by any suitable means, including manually guiding the sheet off the surface, using a sheet handling device, scraping the sheet off the surface, or dropping the sheet from the surface. Especially where it is desired to form a rippled sheet, the sheet may be removed by the use of a doctor blade in relative motion to the surface. The effectiveness of ripple formation is dependent upon the angle of the doctor blade to the surface at the point of contact, the apparent direction of approach of the layer to the blade and the type of doctor blade used. For example, where a roller is used as the surface, the layer should approach the blade in a downwarddirection and the angle of the blade should be between the angle 90° and 40° from the vertical section of the roller. In order to improve ripple formation it is preferable to use a blade with a sharpened point rather than a flattened end. A suitable pressure for the doctor blade will readily be ascertainable by one skilled in the art; it may range from a very light pressure (such as 5 kg/m 2 ) . As an example, the doctor blade may bear against a roller at a pressure in the order of 250 psi (1.8 x 10 5 kg/m 2 ). Collecting the food product by means of a doctor blade results in the food product being collected in a sheet-like form. It will be appreciated that the sheet may be allowed to form a relatively large area, or may be chopped, cut, torn or otherwise reduced in size (laterally and/or longitudinally) as it is removed from the surface. The sheet may be subjected to further processing, for example: (a) folding the sheet to form a layered structure; (b) baking the sheet to form a biscuit-like structure; and/or (c) setting the sheet in a gel-like matrix. Often the sheet will be allowed to fold onto itself, and this may form the requisite layered structure described under (a) above. The weight of the sheet itself may be sufficient to give sufficient density to the layered structure, but pressure may alternatively be applied to increase the density of the structure. The pressure will generally be in the order of from 0.1 to 2 atmospheres (1 x 10 4 to 2.1 x 10 5 kg/m 2 ) , for example in the order of 1 atmosphere (1 x 10 5 kg/m 2 ) . All pressures are guaged pressures. The addition of such pressure may be conveniently effected in a mould. The layered structure may be cut into chunks, simulating the appearance of cubes of meat. The chunks may subsequently be cooked, for example in a can (and/or in gravy) . Alternatively or additionally, the sheet may be removed from the surface and baked to form a biscuit-like structure as described under (b) above. Baking will generally be carried out above 100°C, for example at a temperature of from 100 to 250°C. Baking temperatures of 150 to 200°C are typical. Baking may be conveniently be done in an oven, which in a continuous process will be located downstream of the surface. Further in the alternative or additionally, the sheet may be set in a gel-like matrix. Before so setting, the sheet can be shredded or dried, depending on the desired effect to be achieved. The food product may be set in a gel-like matrix by causing it to come into contact with (for example by immersion) a fluid capable of forming a gel-like matrix. The fluid may consist of known gelable meat mixtures known in the art, such as blood, comminuted meats and offal and fat mixtures as used in sausages and meat puddings. Such systems are believed to depend on the denaturation and gelation of proteins to effect texturisation through the addition of salts and/or the application of heat. The fluid may also contain, either as well as or instead of the above ingredients, plant gums or mucilages, which will in general contribute to the texture of the medium. Where desirable for reasons of product aesthetics, the fluid can have a portion or all of the animal protein replaced by vegetable proteins such as soy or wheat gluten. Typically, therefore, the composition of the fluid can therefore comprise from 0.1 to 30%, eg. 5 to 15% protein, with the residue being water, fats flavours, clours, gums and/or thickeners, and cofactors for each or any of them. Protein may alternatively be absent. in which case a different gelling agent, such as a carbohydrate gelling agent, is used. The sheet or a portion thereof can be added, typically at a level of from 5 to 10%, to the fluid, after which the combined system is used to set, for example by inducing gelation and/or thickening. The precise method of setting is not important and will depend on the functional properties of such gelling and/or thickening agents as are present. For example, proteinaceous agents such as albumins or caseins may be heat set, while plant gums such as alginates and pectates may be gelled with calcium or other (generally divalent) metal salts, or hot carrageenan solutions merely left to gel on cooling. The effect of setting the product initially obtained as a sheet will be to provide striations and fracture points within a comparatively amorphous gel. It is then possible, once the gel has set, to break it in irregular pieces or chunks, and a meat-like appearance will be evident in many cases. The pieces or chunks may subsequently be cooked, for example in a can (and/or in gravy) . Depending on their moisture content (which can subsequently be increased or decreased as desired) , products produced by a process in accordance with the invention can either be used on their own or as incorporated ingredients in human or animal foodstuffs, and in particular in petfoods. It will be appreciated that the further processing of the sheet may include all permutations and combinations of each and any of variants (a) , (b) and (c) . The invention also extends to cover products of a process or processes as described above. The invention will now be further described with reference to the following examples. Example 1. Commercially available poultry mechanically recovered meats (MRM) was prepared to give a particle size of 1mm in a COMITROL processor. The raw meats were obtained frozen and the temperature of them kept below 2°C during the size reduction process. The material was applied evenly by pouring on to the surface of a revolving roller so that an even film thickness of 1mm was obtained. The roller surface was heated and the residence time of the film on the drum was adjusted to give a material temperature of 70°C. A doctor blade was applied to the film at a pressure of 1.6 x 10 5 Kgm~ 2 and a corrugated sheet of material removed. This sheet is able to be used as such, shredded or formed into chunks. The material may be used in heat processed canned foods for human or petfood applications. Example 2. The procedure of Example 1 was followed except that 98% MRM was size reduced to give an average particle size of 1mm at 4°C using a HOBART BOWL CHOPPER cooled with solid C0 2 - 2 % salt was added with mixing to the bowl. The mixture was spread evenly over the roller and processed as in Example 1. The addition of salt was found to give improved texture and appearance to the product. Salt was found to enhance functional material release and a sheet of material was formed. Example 3. A mixture of turkey necks (49%) , beef intestines (49%) , and 2% dry bovine blood was size reduced to 40 microns using a COMITROL whilst maintaining the temperatures of the material below 5°C. The material was then handled as in Example 1, and a sheet of material was formed. Example 3 showed that less functional material that is, the beef intestines (as defined by the Jellotron test in European application number 89301176.7 can be made to work provided (a) functionality is retained and (b) sufficient size reduction occurs to release functional material. Comparative Example 3a. The procedure of Example 3 was followed except that the particle size was 5mm. No homogeneous sheet formation on the heated surface and hence no texturisation was achieved. Comparative Example 3b. The procedure of Example 3 was followed except that the particle size reduction was to 1mm by passing the material through a plate mill under high friction, high shear conditions with a temperature rise to 80°C during grinding. No homogeneous sheet formation on the heated surface and hence no texturisation was achieved. Example 4 . The procedure of Example 1 was followed except that whitefish flesh such as mechanically recovered cod was used instead of poultry. The residence time before removing the film by a doctor blade was controlled to give a material temperature of 50°C. The material was formed as a sheet, as in Examples 1 to 3. Example 5. The procedure of Example 1 was followed except that a mixture comprising mechanically recovered beef (90%) and meat meal (10%) was used instead of poultry. Both materials were reduced to a particle size of less than lmm using a HOBART BOWL CHOPPER and chilling with solid C0 2 and intimately mixed at 10°C. A sheet was sucessfully formed. This demonstrates that a proportion of non-functional material can be incorporated. Examples 6^10. The procedure of Example 5 was followed except that a minority component of gluten (15%) , soya (20%) , peaflour (30%) , feathermeal (10%) and powdered dried skin (10%) was used, respectively to replace the meat meal entirely and where the addition level is above 10% to substitute for additional fractions of the MRM. In all cases suitable sheets were obtained which could be processed in aesthetically pleasing forms in petfood products.

Claims: CLAIMS 1. A process for producing a sheet of proteinaceous product, the process comprising comminuting a material comprising heat-coagulable meat without substantially heat-coagulating the meat, and applying a layer comprising the comminuted meat which has not substantially lost its heat coagulability to a surface on which the layer is at least partially heat-coagulated to form a sheet, and removing the sheet from the surface. 2. A process as claimed in claim 1, wherein heat-coagulable meat is derived from muscle meat, heart, liver and/or kidney. 3. A process as claimed in claim 1 or 2, wherein the material to be comminuted comprises an edible substance in addition to the heat-coagulable meat. 4. A process as claimed in claim 1, 2 or 3, wherein the temperature of the material during comminution is not more than 10°C and not less than -20°C. 5. A process as claimed in any one of claims 1 to 4, wherein after comminution the meat is applied under pressure as a layer to a forming surface. 6. A process as claimed in claim 5, wherein the surface to which the layer comprising the comminuted meat is applied is the surface of a rotating roller. 7. A process as claimed in claim 5 or 6, wherein the surface is heated so as to heat-coagulate the layer on the surface to form a sheet. 8. A process as claimed in claim 7, wherein the temperature of the layer when the layer is heat- coagulated is in the range from 60 to 80°C where substantially non-fish heat-coagulable meat is to be coagulated, and in the range 40 to 50°C where substantially heat-coagulable fish meat is to be coagulated. 9. A process as claimed in any one of claims 5 to 8, comprising smoothing the layer on the surface. 10. A process as claimed in any one of claims 1 to 9, wherein the sheet is removed from the surface by the use of a doctor blade in relative motion to the surface. 11. A process as claimed in any one of claims 1 to 10, wherein the sheet so formed is further processed by: (a) folding the sheet to form a layered structure; (b) baking the sheet to form a biscuit-like structure; and/or (c) setting the sheet in a gel-like matrix. 12. A product of a process as claimed in any one of claims 1 to 11.

Inventors: SPEIRS CHARLES, SPEIRS, CHARLES
Applicants: NADREPH LTD, NADREPH LIMITED
Application year: 1990
Main classification: A23L1
IPC codes: A23L1