Application of glutamine transaminase (TG enzyme) in food processing

Glutamine transaminase is widely found in animals, plants and microorganisms in nature. It is an acyltransferase that causes covalent cross-linking between proteins (or peptides) by catalyzing interprotein (or internal) acyl transfer reactions. Linked enzymes, this cross-linking has a significant impact on protein properties, gelling ability, thermal stability and water holding capacity. Glutamine transaminase can improve the structure and functional properties of proteins, giving food proteins a unique texture and texture, so they have been obtained in food processing industries such as meat products, aquatic products, soy products, pasta products, rice products and dairy products. A wide range of applications.

The use of glutamine transaminase in food is legally based. In GB2760, glutamine transaminase is a processing aid for food additives. It acts as a stabilizer and coagulant in soy products and stipulates that its maximum use is 0.25g / kg, clearly stated that the source of glutamine transaminase is the porch spheroid hyphae.

1. Glutamine transaminase and soy protein

Glutamine transaminase can be combined with soy protein to make small protein meat instead of real meat. Soybean separation plays a role as a "protein chaperone". 1 kg of soy protein isolate and 4 kg of water plus three-thousandths of the TG enzyme of the protein amount were kneaded for 6-8 minutes, potted for 24 hours, and allowed to stand at 0-5 °C. The replacement for real meat is generally 5-10% and should not exceed 25%. In the process of use, first put the prepared protein into the meat grinder and make the small-sized protein meat. Do not twist too fine, do not twist into meat. The protein content of the soy protein isolate used is higher than 90%, soy protein isolate cannot be placed for too long, not more than 4 or 5 months, because the gelatinity of soy protein isolate may be lost instantaneously.

Glutamine transaminase can also be directly added to cross-linked meat. The disadvantage is that there is not enough reaction time to fully react. The direct addition method is mainly applied to high-grade meat products with good meat quality. It can also be used in two ways. First, the meat protein is added and then added to the meat. Glutamine transaminase is applied to high-grade meatballs, meatballs, ham, bacon and sausage. In the processing of meat products, myosin and actin are important components in muscle and play a key role in maintaining muscle water retention and adhesion. In the case of heat, a complex heat-induced gel space network structure is formed between the myosin molecules and between the actomyosin molecules, so that the meat products have the characteristics of elasticity, slicing, water retention and the like. Adding TG enzyme to meat products, in addition to the above forces, can form another covalent bond between muscle protein molecules. This covalent bond has strong interaction and enables protein molecules to bind more tightly. Together, the formation of a muscle protein gel system is maintained, meat quality is improved, meat elasticity, gel strength, texture, appearance, and mouthfeel are improved. TG enzyme is applied to steaks, pork chops, chicken chops, Brazilian barbecue, etc. It can also be used for the reconstitution of minced meat such as mutton, pork sirloin, and hot pot. The meat block reconstitution can make full use of the by-products in the processing of meat products (such as small meat pieces, boneless meat, fat and other scraps) to cross-link under appropriate conditions, reconstitute large pieces of meat, and increase the utilization value and Improve economic efficiency. When the recombinant meat is produced by the TG enzyme, not only the minced meat can be bonded together, but also various non-meat proteins can be cross-linked to the meat protein, which can obviously improve the taste, flavor, tissue structure and nutrition of the meat product.

2. Application of glutamine transaminase in aquatic products

The addition of TG enzyme to meatballs can increase the elasticity of the product. Fish protein such as fish and shrimp balls and surimi products can form a gel at a low temperature, which is a result of the action of glutamine transaminase contained in the fish itself. Because fish endogenous glutamine transaminase is very small, it is difficult to work when the quality of raw materials is poor, but by adding exogenous glutamine transaminase, the gel strength of the product can be improved, the cooking loss can be reduced, and the product quality can be improved. .

3. Application of glutamine transaminase in tofu

Thousand pages of tofu, also known as 100 pages of tofu, thousand tofu, Q crispy tofu, etc., is a kind of tofu that originated in Taiwan and was later created by the technical improvement of mainland R&D personnel. Its appearance is completely subversive. The concept of traditional tofu. Thousand-page tofu is a vegetarian product made from soy protein and modified starch. It is a low-fat, low-carb, protein-rich New Century cuisine. The main raw material of the thousand-page tofu is soy protein isolate, which is formed by changing the molecular structure of soy protein isolate. Therefore, it has good elasticity and toughness. It is smooth, tender and delicious, can be fried and fried, and can be fried. The unique aroma of water tofu. Generally, if the gel value is low, the 1,000-page tofu produced is relatively soft, and can not withstand the cooking process such as stewing. If the TG enzyme is added, the gel elastic hardness of the soy protein isolate is increased by the cross-linking action of the enzyme, and the color of the thousand-page tofu can be increased to be whiter and more delicate. The traditional thousand-page tofu complex process is simplified, and it can be easily produced in a few simple steps, and the investment cost is reduced.

4. Application in dairy products

Casein is a good substrate for glutamine transaminase, with β-, κ-casein being superior to а-casein. In cheese production, after treatment with glutamine transaminase, whey protein and casein are cross-linked to increase cheese yield. High-quality low-fat yogurt can be produced using glutamine transaminase in yogurt production. After the protein in the milk is treated with glutamine transaminase, it can be used as an edible coating film and packaging material to improve the appearance and shelf life of the product.

5. Application of glutamine transaminase in plant protein products

Glutamine transaminase crosslinks lysine to gluten, casein, and soy protein, which is most effective in cross-linking with gluten. Glutamine transaminase does not improve the dough properties for high quality wheat. It can promote dough properties, increase bread volume and improve tissue structure for low quality wheat. Adding a small amount of glutamine transaminase to the cake can improve the taste and appearance of the cake.

6.Application of glutamine transaminase in the preparation of packaging film

Glutamine transaminase can be used to prepare films, which can replace food packaging films made of polymer synthetic materials. The film prepared by glutamine transaminase has the advantages of high tensile strength, insoluble in water and other solvents. The gelatin used today is derived from mammals, such as cattle or pigs, at a higher cost. Fish gelatin is a potential alternative, but the physical and thermal properties of fish gelatin limit its use in many ways. Modification of gelatin by glutamine transaminase can greatly improve its physical properties and expand the application range of fish gelatin film. Fish gelatin treated with glutamine transaminase has a significant increase in viscosity, tensile strength, melting point, oxygen barrier properties and molecular weight of the film. Helps to form a film that is resistant to heat and water. After dehydration of casein cross-linked by glutamine transaminase, a water-insoluble film can be obtained; this film can be decomposed by chymotrypsin and is therefore an edible film which can be used as a food packaging material. Encapsulation of lipids or fat-soluble substances to improve the elasticity and water holding capacity of foods.

Glutamine transaminase also has important functional properties that help to increase the nutritional value of the protein. Glutamine transaminase can covalently crosslink essential amino acids (such as lysine) to proteins, which can prevent the destruction of amino acids by Maillard reaction; it can improve the nutritional value of protein. Glutamine transaminase can also introduce the amino acid deficiency into a protein with an unsatisfactory amino acid composition to enhance its nutrition.