WO2002005657A1

WO2002005657A1 - Structured protein food

Info

Publication number: WO2002005657A1
Application number: PCT/NL2001/000539
Authority: WO
Inventors: Wieger Knol; Yang Zhu
Original assignee: Nederlandse Organisatie Voor Toegepast- Natuurwetenschappelijk Onderzoek Tno
Priority date: 2000-07-13
Filing date: 2001-07-13
Publication date: 2002-01-24
Also published as: AU2001276784A1

Abstract

A textured proteinaceous food product can be produced in a controlled and safe manner by addding a starter culture composed of one or more selected gas-forming food-grade micro-organisms to a protein substrate, fermenting the protein substrate with said culture in the presence of water, and subjecting the fermented protein substrate to a heat treatment. The proteins substrate is preferably vegetable, such as gluten or legume protein. This process results in a meat-like product having desired and reproducible texture and taste.

Description

Structured protein food

[0001] The present invention relates to a textured food product or food ingredient obtained from natural proteins and to a process of producing such product. [0002] There is an increasing need to substitute meat proteins in foodstuffs by proteins from other sources, especially vegetable sources, in order to reduce cost and environmental burden, avoid unnecessary slaughter of animals, improve protein efficiency in global food supply etc. These substitute proteins should have similar functional properties like meat, in particular as to its texture (structure, firmness, mouth- feel, bite). [0003] There are basically two approaches for producing substitute food protein. One approach is to use a non-animal organism that produces sufficient amounts of suitable protein, and to process the protein-rich organism into a foodstuff or food ingredient having the required texture. For example, EP-A-123434 and EP-A-986960 disclose production of fungal material as food protein using Fusarium graminearum (the commercial product being known as "Quorn") and Rhizopus oryzae, respectively. This approach has only been described for fungi. Moreover, the fungal products are rather expensive.

[0004] The other approach is to use protein material which itself is not directly suitable as a protein foodstuff, and to treat the protein material by enzymatic or other means so as to obtain the required texture, taste, mouthfeel, etc. As an example, EP-A-963704 discloses modification of protein-containing food material such as wheat flour, soy protein or animal protein by a trans-glutaminase and an oxidoreductase to improve its texture. Such enzymatic processes are expensive. [0005] Most current vegetable proteins used as meat substitutes are derived from soy. Soy is more and more often genetically modified and is therefore less attractive for some consumer groups. Furthermore, most meat substitutes are expensive as explained above. For many inexpensive protein sources, the available processes for upgrading them to acceptable food proteins have drawbacks such as price, microbial safety and the like, and the presently available meat substitutes have a narrow and only moderately tuneable spectrum of taste and other properties. Thus there is a need for protein products having novel characteristics.

[0006] US 3,885,048 discloses the production of a tempeh-like product by processing beans, wheat and sesame using non-gasforming fungi and heat-sterilising the product. According to GB 1,356,353, soy milk is treated with non-gasforming Streptococci to produce a curd, which is then processed further to a cheese-like or other food product. GB 1,543,463 discloses the use of whey protein or wheat bran to produce a protein-rich extract by aerobic fermentation with yeast or lactic acid bacteria. [0007] It was found according to the invention that a useful protein food product or food ingredient having the texture of meat or processed egg protein or other food protein can be obtained from relatively inexpensive raw materials. According to the invention, a defined starter culture composed of one or more food-grade micro-organisms is added to the protein substrate, the protein substrate is fermented in the presence of water, and the fermented protein substrate is subjected to a heat treatment.

[0008] The process of the invention allows the production of textured proteinaceous products suitable for substituting meat-like components in a variety of food products. As a result of the inoculation with a relatively high number of selected cells, the process of the invention is a fast process, with fermentation times in the order of several hours up to one or more days. The selection of protein sources and micro-organisms permits a fine-tuning of the properties of the final protein product in terms of structure, firmness, mouth-feel, bite, taste and flavour.

[0009] The protein substrate is a non-textured proteinaceous material and may comprise proteins from vegetable source, or from animal source, or even from micro-organisms. Vegetable proteins include gluten (wheat, maize, rye and other cereals), rice protein, legume protein (pea, lupine, soy etc.), grass protein, potato protein, spent malt protein and other protein-containing (residual) material. Animal proteins include chicken (meat) protein, egg protein, milk protein, blood protein, skin collagen, hydrolysed keratin and the like. Preferably, the protein is derived from vegetable sources. The raw protein may be pre-treated by hydrolysis, decoloration, isolation, milling, drying etc. by standard methods, before being used according to the invention. The protein substrate to be used according to the invention should contain at least 10%, preferably at least 20% by weight, more preferably at least 30% by weight of protein; other materials, such as poly- saccharides, do not generally interfere with the process of the invention. If necessary, small amounts of food-grade hydrocoUoids such as xanthan, pectin, agar, carragheenan, carboxymethyl cellulose and the like, can be used to ensure sufficient viscoelasticity of the mixture, and thus to produce sufficient texturing effect. The process is carried out without aeration and preferably without agitation, so as to allow anaerobic fermentation or limited aerobic fermentation. Strict aerobic fermentation should be avoided. [0010] The micro-organisms to be used in the process of the invention are at least partly gas-forming and are preferably accepted for use in food. Acceptability for food use may correspond to the notions "Generally Recognised As Safe" (GRAS) or "History of safe use". The micro-organisms may be yeasts, bacteria or possibly moulds. Suitable yeasts include Saccharomyces cerevisiae (commercially available as baker's yeast) and other food-grade yeasts such as Candida utilis, C. pseudotropicalis, C. lipolytica, Kluyvero- myces lactis and K. marxianus. Suitable bacteria include heterofermentative lactic acid bacteria. These comprise e.g. Leuconostoc mesenteroides, L. citrovorum, L. dextranicum, Lactobacillus delbrueckii, L. acidophilus, L. buchneri and L. brevis. In addition to the gas-forming micro-organisms, other useful strains may be present, such as Pediococcus, Lactococcus, Propionibacterium or Bifidobacterium species. Also mixtures of (food grade) micro-organisms can be used, such as commercially available "sour dough" starter cultures or dedicated combinations of micro-organisms. The amount of micro-organisms to be added to the protein should be sufficient for rapid leavening of the protein/water mixture and will depend on the applied starter organism(s) and its gas-forming capacity. The number of required active cells will be above 10⁴ per gram, up to about 10⁹ g of the protein/water mixture, or above 2.10⁴ up to about 2.10⁹ per g of protein, preferably from about 10⁵ to about 10⁸ cells per g of protein substrate. [0011] The fermentation conditions are chosen as a function of the desired product properties. Firstly, the microbial species and the amount of cells per g of substrate are important for the final result. Relatively high numbers of cells will accelerate the process and diminish the risk of contamination with undesired micro-organisms. The temperature is chosen in relation to the particular micro-organism, higher temperatures generally accelerating the process. Prolonged treatment or treatment at relatively high temperatures (e.g. 30-40°C) may enhance proteolysis, which may sometimes be useful in further adapting the texture of the product and improving taste and flavour. Lactic acid bacteria have an advantage in that they will decrease the pH to about 4-5, and thus the product will be better protected against microbial contamination and spoilage. In general, the process temperature will be between 5 and 55°C, preferably between 20 and 35°C. [0012] The concentration and composition of the protein substrate must be such that gas formation can occur and can result in the desired structure. Usually, the protein is therefore used in a mixture with water, containing 20-80 wt.% of protein. For sufficient gas production, the substrate should also contain a small amount of fermentable carbo- hydrates, e.g. at least 0.5 wt.%, especially 1-25% on dry weight basis of the total substrate. The fermentable substrate may be glucose or maltose or, if the system contains enzymes for degrading other carbohydrates, such as amylases, glucosidases, galactosidases, the corresponding degradable carbohydrates such as starch, starch fractions, lactose, etc.

[0013] After the fermentation, the product is subjected to heat treatment in order to fix the structure produced during the fermentation by denaturation of the protein. Also, the residual microbial activity is stopped by the heat treatment. The heat treatment may be simple high temperature, e.g. in an oven at 60-140°C. However, excessive dehydration should be avoided, for example by heating in a closed system. A suitable heat treatment is a treatment with steam. Alternatively, microwave treatment may be used. If desired, the product can subsequently be dried, cooled, freeze-dried, and brought in desired shape by cutting, milling, moulding and the like. [0014] Other food components can be added before, during or after fermentation or even after the optional drying and shaping. Such components include colorants, flavourings, preservatives, process aids, fillers, and the like.

[0015] The product of the process of the invention can be used for a variety of purposes. These include meat substitutes in vegetarian product, inexpensive meat-like ingredients in meat products, meat-like ingredients in salads, dressings, soups, textured protein in composite or convenience foods such as pizza's, pastry etc.

Example 1

[0016] Active wheat gluten (100 g, obtained from Avebe Latenstein, Nijmegen, NL) was mixed with 125 ml tap water, wherein 1 gram of pressed baker's yeast (Koningsgist, Gist- brocades, NL) was suspended. The mixture was kneaded by hand for two minutes and subsequently incubated for 5 hours without aeration in a 1 liter glass container at ambient temperature for leavening. The leavened dough was steam-heated in a pressure cooker (at normal pressure) for 2 hours and left to cool down. After steaming a light brown textured product with a bread-like structure was obtained. The textured product was sliced and used as the main (meat-like) ingredient in a dish with mushrooms and additional condiments for flavouring. Example 2

[0017] Example 1 was repeated using a freshly grown culture of Saccharomyces cerevisiae and slightly different conditions. The strain isolated from commercial baker's yeast (Koningsgist, Gist-brocades) was cultivated in 100 ml glucose yeast-extract broth for 2 days at 25 °C. The cells of 20 ml of the culture were centrifuged, washed twice with sterile 0.85 % NaCl solution and suspended in 90 ml tap water in a 200 ml beaker. To this suspension active wheat gluten (45 g, obtained from Avebe Latenstein) was added. The mixture was kneaded with a household mixer with dough-hooks (Philips Type HM3060) for 1.5 minutes. The dough was incubated overnight at ambient temperature and steam- treated as in example 1. The obtained product had similar characteristics to that from example 1.

Example 3

[0018] Example 2 was repeated using a culture of Leuconostoc mesenteroides instead of the yeast The bacterium was cultivated in 100 ml MRS broth (Oxoid) for 2 days at 30 °C. Using 20 ml of this Leuconostoc culture a textured wheat gluten product was prepared following the same procedure as for example 2. The dough as well as the final product prepared with L. mesenteroides differed from that prepared by Saccharomyces cerevisiae with respect to the pH, stickiness and appearance as shown in Table 1.

Table 1.

Claims

1. A process of producing a textured proteinaceous food product comprising adding a starter culture composed of one or more gas-forming food-grade microorganisms to a protein substrate, fermenting the protein substrate with said culture in the presence of water, and subjecting the fermented protein substrate to a heat treatment.

2. A process according to claim 1, wherein said protein substrate comprises a vegetable protein.

3. A process according to claim 2, wherein said protein is selected from gluten, legume protein and potato protein.

4. A process according to any one of claims 1-3, wherein said food-grade microorganism comprises a yeast, in particular of the genus Saccharomyces.

5. A process according to any one of claims 1-4, wherein said food-grade microorganism comprises a lactic acid bacterium, in particular of the genus Leuconostoc.

6. A process according to any one of claims 1-5, wherein said protein substrate consists of at least 20%, by dry weight, of protein.

7. A process according to any one of claims 1-6, wherein between 10 and 10 cells of the food-grade micro-organism are added per g of protein substrate.

8. A process according to any one of claims 1-7, wherein said heat treatment comprises a steam treatment or a microwave treatment.

9. A textured proteinaceous food product, obtainable by fermenting a vegetable protein with a lactic acid bacterium and or a yeast.