Transglutaminase

Transglutaminase

Transglutaminase (TG enzyme) is a monomeric protein with an active center composed of 331 amino groups and a molecular weight of about 38,000. It can catalyze the covalent crosslinking of protein peptides within and between molecules, thereby improving the structure of the protein And function, it has significant effects on protein properties such as: foaming, emulsifying, emulsifying stability, thermal stability, water retention and gelling ability, thereby improving the flavor, taste, texture and appearance of food. Traditional meat processing techniques usually add large amounts of salt and phosphoric acid to improve their water holding capacity, consistency and texture. Recently, foods with less salt and less phosphoric acid have been widely promoted, but their texture and physical properties are not satisfactory. TG enzyme can replace some of the quality improvers added in the processing of meat products-phosphate, to produce low-salt meat products. It can be applied to aquatic products, ham, sausage, noodles, tofu, etc. Under the condition of 40～45 ℃ and pH 6-7, TG enzyme only needs to add 0.1-0.3% to achieve obvious effect.

Functions

The main functional factor of TG is glutamine transaminase. This enzyme is widely present in humans, higher animals, plants and microorganisms, and can catalyze cross-linking between or within protein molecules, connections between proteins and amino acids, and hydrolysis of glutamine residues within protein molecules. Through these reactions, the functional properties of various proteins can be improved, such as nutritional value, texture structure, mouthfeel and shelf life.

Features

• Strong adhesion. The covalent health catalyzed by the enzyme is difficult to break under normal non-enzymatic catalysis conditions, so after the minced meat is formed by the enzyme treatment, it will not be scattered after freezing, slicing and cooking.
• Good PH stability. The optimal pH of TG is 6.0, but the enzyme has high activity in the range of pH 5.0 to 8.0.
• Strong thermal stability. The optimum temperature of TG is around 50 ℃, and it has high activity in the range of 45 ℃ -55 ℃. Especially in protein food systems, the thermal stability of the enzyme will be significantly improved, this feature makes it will not be quickly inactivated in the general food processing process.
• In the process of catalyzing protein reaction of TG, temperature (within the temperature of maintaining enzyme activity) is negatively correlated with time: the reaction temperature is high and the reaction time is short; otherwise, the lower the temperature, the longer the time. The physical and chemical properties of different types of food determine the relationship between temperature and time during the reaction.
• Safety. Because TG is widely present in animal tissues, people have been eating foods containing e- (g-glutamyl) lysine isopeptide bonds catalyzed by TG. Therefore, new foods produced with TG are not only safe for humans, also beneficial to human health. Therefore, glutamine transaminase is a new type of food additive with very obvious use effect and very wide application.

Applications

• Improve food texture. It can improve many important properties of proteins by catalyzing the cross-linking that occurs between protein molecules. If the enzyme is used to produce recombinant meat, it can not only bind the minced meat together, but also cross-link various non-meat proteins to the meat protein, obviously improving the taste, flavor, tissue structure and nutrition of meat products.terrine.
• Improve the nutritional value of protein. It can covalently cross-link certain essential amino acids (such as lysine) to proteins to prevent the destruction of amino acids by Maillard reaction, thereby improving the nutritional value of proteins. Glutamine transaminase can also introduce the lack of amino acids into proteins whose amino acid composition is not ideal. People in developing countries are particularly interested in this.
• Form a heat and water-resistant film. After dehydration of the casein cross-linked by the enzyme, a water-insoluble film can be obtained, which can be decomposed by chymotrypsin, so it is an edible film and can be used as a food packaging material.
• Used for embedding lipids or fat-soluble substances.
• Improve food flexibility and water holding capacity.

Reference

1. Griffin M, et al. Transglutaminases: nature's biological glues. The Biochemical Journal. 2002, 368 (Pt 2): 377–96.