PROTEIN PREPARATION

Abstract: The present invention relates to a method for preparing a protein preparation having one or more of emulsifying, gelling, water-binding and viscosity enhancing properties, comprising treating a solution of a mixture comprising a plant protein and a globular protein with the enzyme transglutaminase and optionally drying the treated mixture. Preferably the plant protein is wheat protein, in particular wheat gluten protein. The globular protein is preferably whey protein. The protein preparation obtained is also part of this invention.

Description: PROTEIN PREPARATION The invention relates to a method for preparing a protein preparation having one or more of emulsifying, gelling, water-binding and viscosity enhancing properties. The invention further relates to the protein preparation obtainable by means of such method, to the use of such preparation and to products comprising such preparation. Fats and oils add flavors and enhance and release the flavors of other ingredients in food. Fats interact with other ingredients to develop and mold texture, mouthfeel, and the overall sensation of lubricity of food. Melting points of fat determine the food's softness, chewiness, and creaminess. Fat is a complex, highly functional ingredient that contributes to the way food tastes. Consumers become more and more aware of the necessity to lower the amount of fat in their diet. But although the consumer is actively searching for reduced calorie, i.e. low fat, foods and beverages, he requires that they have similar taste and mouthfeel to their full calorie counterparts. Fat replacers should thus mimic the properties of fat. Increased viscosity in a product is associated with taste as it mimics the mouthfeel of fat. Fat replacers should therefore preferably contribute to the viscosity of the food product they are part of. In addition, many food products, like soups, sauces and meat products, such as sausages, are emulsions, in particular oil-in-water emulsions, which require emulsification, even when the amount of oil therein is lower. Various attempts have been made to provide alternative additives that lead to a stable emulsification and increased viscosity of the product they are part of. Examples of such products are casein, hydrocolloids, carrageenan, pectin, alginate, modified starches, various proteins and gelatin. The latter is a product derived from the bones, hides or skin of animals and may therefore be subject to the risk of BSE. None of these products lead to acceptable end products so their usefulness is limited. In view of the above it is the object of the present invention to provide a new ingredient that has emulsifying and/or gelling and/or water-binding and/or viscosity enhancing properties. This is achieved by the invention by means of a method, comprising treating a solution of a mixture comprising a plant protein and a globular protein with the enzyme transgluta inase and optionally drying the treated mixture. The protein preparation thus obtained can be used as a food ingredient that has one or more of the desired properties. The plant protein is preferably a cereal protein, more preferably a wheat protein, and most preferably wheat gluten protein that is preferably soluble. In a preferred embodiment the ingredient has all the above properties. It was found according to the invention that the mixture of the plant protein and globular protein should preferably be made prior to performing the enzymatic reaction. When the plant protein is wheat protein it can be any wheat protein, but is preferably a soluble wheat protein. Soluble wheat gluten protein is found to be particularly suitable. Such soluble wheat gluten protein is a product known to the person skilled in the art and can for example be obtained from Amylum (as Soluble Wheat Protein or "SWP") or ADM (Wheatpro) . The wheat gluten is preferably solubilized at neutral pH for optimal performance of the transglutaminase in the process that follows. The globular protein can be selected from various proteins, but is preferably rich in lysine. Preferred are milk whey proteins, blood proteins and egg white proteins. The advantage of whey proteins is its outstanding nutritional protein quality, its excellent solubility and bland taste. Moreover, it is easily available as a by-product from the cheese industry. The ratio of the wheat protein and the globular protein in the solution is between 95:5 and 5:95, preferably between 75:25 and 25:75, more preferably between 60:40 and 40:60. The enzyme to be used in the method of the invention is transglutaminase (EC 2.3.2.13). Transglutaminase catalyzes acyl-transfer reactions in which the γ-carboxamide group of glutamine is the acyl donor and usually a nucleophilic reagent such as the e- amino group of lysine or water represents the acyl acceptor with the formation of a new isopeptide bond. Ammonia is released in the process. Transglutaminase is wide-spread in animal tissue and also occurs in microorganisms. Transglutaminase may either be calcium- dependent or calcium-independent. The latter are usually found in microorganisms, whereas the former are described to be present in various locations in the animal body, such as guinea pig liver, animal blood or fish. Transglutaminase is currently available from Ajinomoto or Sigma. The calcium-independent transgluta inases are preferred in view of process economics and performance. The amount of transglutaminase lies between 0.2 and 200 units per gram protein in the solution, preferably between 1 and 100 units per gram protein in the solution, more preferably between 10 and 50 units per gram protein in the solution. The specific activity of transglutaminase is determined using the well known hydroxamate method (e.g. US-5, 156, 956) . 1 Unit of transglutaminase activity is the amount of enzyme that catalyses the formation of 1 μmol of hydroxamic acid per minute from carbobenzoxy-L-glutaminylglycine (pH 6.0, 37°C) . The enzymatic reaction with transglutaminase is carried out for 5 minutes to 48 hours at 0 to 65 °C, preferably for 2 to 24 hours at 40 to 50 °C. It is preferred that after the enzymatic reaction the solution is heated, firstly to pasteurize the mixture in order to achieve a hygienic condition, and secondly to inactivate the enzyme. Inactivation of the enzyme is done to avoid undesirable enzyme activity in the end product in which the ingredient is applied. Enzyme inactivation and pasteurization can be achieved by heating the solution to 80 to 140 °C for 1 second to 30 minutes. Various methods exist for drying the protein preparation, for example spray drying, freeze drying or roller drying. According to a further aspect thereof, the invention relates to a protein preparation having one or more of emulsifying, gelling, water-binding and viscosity enhancing properties, which is obtainable by the method of the invention. This protein preparation can be used as an emulsifier, gelling agent, water-binding agent or viscosity enhancing agent. It is self-evident that two or more of these functions can be combined in one additive or ingredient. The properties that are displayed also depend on the food product in which the ingredient is used. The protein preparation preferably takes the form of a powder, may be a granulate, or may be part of a blend with other food ingredients, such as fats, maltodextrines, emulsifiers, carbohydrates. The ingredient of the invention is added in a suitable amount to the rest of the food product ingredients depending on the type of application used. In case the other ingredients comprise both water and an oil or fat, the ingredient of the invention will act as an emulsifier and will increase the viscosity of the mixture of ingredients. After heating of the product the ingredient will form a gel. It was found that the protein preparation of the invention has furthermore excellent water-binding properties. The products that may comprise the ingredient of the invention are novel by virtue of the presence therein of the ingredient. The invention thus also relates to emulsions in general, and various food products in particular, which comprise as an ingredient a protein preparation as claimed. Food products in which the protein preparation of the invention may be used as an ingredient comprise, but are not limited to meat paste products, such as sausages, fish meat paste products, soups, sauces, such as mayonnaise and dressings, milk products, such as ice cream and yoghurt, bakery products, such as sponge cake, and pasta products. In this application the terms "ingredient" and "protein preparation" are used interchangeably, although "protein preparation" is the more general term, whereas "ingredient" refers to the use of the preparation in a food product. The present invention will be further elucidated in the examples that follow and that are in no way intended to limit the invention. In the examples reference is made to the figure which shows the difference between a protein preparation of the invention (left) and a mixture of its ingredients without enzymatic treatment (right) . EXAMPLES EXAMPLE 1 Preparation of a cross-linked protein product using soluble wheat gluten protein and whey proteins A 10% solids solution is prepared by dissolving 2 kg of soluble wheat gluten protein (SWP100, Amylum, Belgium) and 1 kg whey protein concentrate WPC 80 (Esprion 580, DMV International, The Netherlands) in 27 1. process water of 50 °C. The pH of the solution is then adjusted to 7.0 using 1M NaOH. To start the reaction 50 activity units of microbial transglutaminase (Ajinomoto, Japan) was added. The temperature during the reaction was maintained at 50 °C. After 4 hours the reaction was stopped by pasteurisation (heated to 80 °C and held at this elevated temperature for 5 minutes) . Hereafter the solution was spray dried on a Buchi spray drier to produce sample SI. Comparative products were made according Comparative Examples 2 and 3 to test if the benefits of the invention are specific for the mixture of these proteins. COMPARATIVE EXAMPLE 2 Preparation of a cross-linked protein product using soluble wheat gluten protein A 10% solids solution is prepared by dissolving 2 kg of soluble wheat gluten protein SWP100 (Amylum, Belgium) in 18 1. process water of 50 °C. The pH of the solution is then adjusted to 7.0 using 1M NaOH. The reaction was started by adding 50 activity units of microbial transglutaminase. The temperature during the reaction was maintained at 50 °C. After 4 hours the reaction was stopped by pasteurisation after which the solution was dried to produce sample S2. COMPARATIVE EXAMPLE 3 Preparation of a cross-linked protein product using whey protein concentrate The same process described as in comparative example 2 was used to treat WPC 80 (Esprion 580, DMV International. This produced sample S3. EXAMPLE 4 Preparation of a cross-linked protein product using wheat gluten protein and egg white protein A 15% solids solution is prepared by dissolving 3 kg of Wheatpro 80 (ADM, USA) and 1.5 kg dried egg whites (NIVE, The Netherlands) in 25.5 1. process water of 50 °C. The pH of the solution is then adjusted to 7.0 using IM NaOH. To start the reaction 20 activity units of microbial transglutaminase (Ajinomoto) was added. The temperature during the reaction was maintained at 50 °C. After 10 hours the reaction was stopped by pasteurisation. The reaction mixture was heated to 80°C and held at this elevated temperature for 5 minutes. Hereafter the solution was freeze dried. This sample showed comparable properties as sample SI. EXAMPLE 5 Testing emulsification and gelling properties The protein samples (20 g) to be tested were dissolved in 240 ml water using a variable speed mixer. To this solution, 300 ml soy oil is slowly added. The mixture is further emulsified for 3 minutes. Part of the emulsions were poured into small metal containers and sealed tight. The containers were statically pasteurised by heating to 85 °C for 45 minutes. After cooling to room temperature the contents were visually inspected to determine if a gel had formed. The viscosity of the emulsions was measured before pasteurisation using the Physica UDS 200 (Paar Physica) rheometer. Viscosity was measured at 25 °C using the Z3 DIN set-up. Various samples were tested to determine whether the combination of the proteins prior to the enzymatic reaction was essential. To this effect the following samples were used: the two protein preparations without addition of enzyme (SWP 100 + Esprion 580) the enzymatically treated soluble wheat gluten protein in combination with untreated whey protein (S2 + Esprion 580) - the enzymatically treated whey protein in combination with untreated soluble wheat gluten protein (SWP100 + S3) the two protein preparations after separate enzymatic treatment (S2 + S3) - a mixture of the two proteins treated with transglutaminase (SI, according to the invention) Table 1 shows the results. Table 1 Viscosity and gel formation a ratio of 2:1 was used for SWPIOO and Esprion 580 in all samples It is clear that the two proteins need to be combined prior to the enzymatic treatment with transglutaminase. The figure further illustrates the effects seen. The emulsion made with the mixture of SWPIOO and Esprion 580 is liquid whereas the emulsion made with the TG treated mixture (SI) forms a gel. EXAMPLE 6 Testing emulsifying properties The emulsion forming properties were evaluated by measuring the particle size distribution of the fresh emulsions. This was done using a Malvern Mastersizer 2000. The measurement parameters were as follows: Refractive index: 1.47 Absorption: 0 Size range: 0.020 to 2000.0 μ Analysis model: general purpose (spherical) The results are listed in the table 2, Table 2 a ratio of 2 : 1 was used for SWPIOO and Esprion 580 in all samples D[3,2]: average particle size d[0.5]: 50% of the particles is smaller than the indicated value The results show that emulsions made with the transglutaminase treated mixture of wheat and whey proteins (SI) have a significant smaller D[3,2], span and d(0.5) than the others. This indicates that the emulsion is mono-disperse and will have good stability. EXAMPLE 7 Performance of the protein preparation of the invention in Frankfurter type sausage In order to test the protein preparation of the invention in a food product, sausages were prepared. The recipe of the product is listed in table 3 Table 3 Frankfurter recipe Ingredient % Beef brisket 18.00 Pork shoulder meat 14.00 Phosphates 0.30 Salt containing 0.6% sodium nitrite 2.00 Ice flakes 17.50 1:7:7 Pre-emulsion (*) 15.00 Pork jowl 10.10 Pork back fat 19.50 Spices 0.60 Potato starch 3.00 Total 100.00 (*) This Pre-emulsion is a pre-mix of 1 part of the wheat protein/whey protein complex (SI) , 7 parts of animal fatty tissue and 7 parts of hot water. The procedure for preparation is as follows. A pre-emulsion preparation is prepared in a bowl chopper. The fatty tissue is shortly chopped together with the wheat protein/whey protein complex (SI) . Then, hot water of 80-90 °C is added. The mass is emulsified at maximum speed of the bowl chopper during approx. 3 minutes. The thus obtained pre-emulsion is chilled and stored in the refrigerator until it is used in the sausage batter preparation (usually within 2 days) . Sausage batter is also prepared in the bowl chopper. The beef brisket and pork shoulder meat are chopped shortly at medium speed together with the phosphates and the nitrite containing salt. Then the ice flakes are added portion wise while the bowl chopper is running at maximum speed. When the temperature reaches 4- 5°C the pre-emulsion, the pork jowl and the back fat are added. Chopping at high speed is continued and when the mass reaches a temperature of 10 °C the spices and potato starch are added. Chopping is continued until the temperature of the mass is 12 °C. The obtained sausage batter is vacumised before it is stuffed in the selected casings. Finishing of the sausages is performed in the following manner. After stuffing of the batter in casings the sausages are subsequently: Cured at 54 °C during 15 minutes Dried at 40°C during 10 minutes Smoked at 54 °C during 15 minutes Dry heated at 74 °C during 15 minutes and Steam cooked at 80 °C during 15 minutes After chilling (and if appropriate peeling) of the sausages they are vacuum packed. The sausages thus obtained had excellent eating qualities with respect to taste and mouthfeel. From the examples it follows that the wheat/whey protein complex of the invention is a more viscous and stable emulsion as compared to the separate ingredients. A higher viscosity of the emulsion improves handling and usability. Furthermore, less protein is required to stabilise emulsions of animal fat and water, which gives a price advantage.

Claims: CLAIMS 1. Method for preparing a protein preparation having one or more of emulsifying, gelling, water-binding and viscosity enhancing properties, comprising treating a solution of a mixture comprising a plant protein and a globular protein with the enzyme transglutaminase and optionally drying the treated mixture. 2. Method as claimed in claim 1, wherein the plant protein is a cereal protein. 3. Method as claimed in claim 2 , wherein the cereal protein is a wheat protein. 4. Method as claimed in claim 3 , wherein the wheat protein is wheat gluten protein. 5. Method as claimed in claim 4, wherein the wheat gluten protein is soluble or solubilized wheat gluten protein. 6. Method as claimed in claims 1-5, wherein the globular protein is a whey protein. 7. Method as claimed in claims 1-5, wherein the globular protein is an egg white protein. 8. Method as claimed in claims 1-5, wherein the globular protein is a blood protein or blood serum protein. 9. Method as claimed in claims 1-8, wherein the ratio of the wheat protein and the globular protein in the solution is between 95:5 and 5:95. 10. Method as claimed in claim 9, wherein the ratio of the wheat protein and the globular protein in the solution is between 75:25 and 25:75. 11. Method as claimed in claim 10, wherein the ratio of the wheat protein and the globular protein in the solution is between 60:40 and 40:60. 12. Method as claimed in claims 1-11, wherein the amount of transglutaminase is between 0.2 and 200 units per gram protein in the solution. 13. Method as claimed in claim 12 , wherein the amount of transglutaminase is between 1 and 100 units per gram protein in the solution. 14. Method as claimed in claim 13 , wherein the amount of transglutaminase is between 10 and 50 units per gram protein in the solution. 15. Method as claimed in claims 1-14, wherein the enzymatic reaction with transglutaminase is carried out for 5 minutes to 48 hours at 0 to 65 °C. 16. Method as claimed in claim 15, wherein the enzymatic reaction with transglutaminase is carried out for 2 to 24 hours at 40 to 50 °C. 17. Method as claimed in claims 1-16, wherein after the enzymatic reaction transglutaminase is deacti- vated. 18. Method as claimed in claim 17, wherein the deactivation of transglutaminase is performed by heating the solution to 80 to 140 °C for 1 second to 30 minutes. 19. Method as claimed in claims 1-18, wherein drying of the treated mixture is performed as spray drying, freeze drying or roller drying. 20. Protein preparation having one or more of emulsifying, gelling, water-binding and viscosity enhancing properties, obtainable by a method as claimed in claims 1-19. 21. Protein preparation as claimed in claim 20 for use as an emulsifier. 22. Protein preparation as claimed in claim 20 for use as an gelling agent. 23. Protein preparation as claimed in claim 20 for use as a water-binding agent. 24. Protein preparation as claimed in claim 20 for use as a viscosity enhancing agent. 25. Emulsion, comprising as an emulsifying agent a protein preparation as claimed in claims 20 and 21. 26. Food product, comprising as an ingredient a protein preparation as claimed in claims 20-24. 27. Food product as claimed in claim 26, which food product is selected from the group consisting of meat products, fish meat products, soups, sauces, milk products , bakery products . 28. Food product as claimed in claim 26, which food product is a vegetarian food product, such as a meat replacer.

Inventors: BRONTS HENRICUS MARIA, HENDRICKX ANTONIUS CORNELIUS M, MALLEE LEON FRANCISCUS, BRONTS, HENRICUS, MARIA, HENDRICKX, ANTONIUS, CORNELIUS, MARIA, MALLEE, LEON, FRANCISCUS
Applicants: BRONTS HENRICUS MARIA, CAMPINA MELKUNIE BV, HENDRICKX ANTONIUS CORNELIUS M, MALLEE LEON FRANCISCUS, BRONTS, HENRICUS, MARIA, CAMPINA MELKUNIE B.V., HENDRICKX, ANTONIUS, CORNELIUS, MARIA, MALLEE, LEON, FRANCISCUS
Application year: 2001
Main classification: A23J3
IPC codes: A23J3, A23L1