Application of TG Enzyme in Different Protein Systems

Transglutaminase enzyme, also known as TG enzyme, is a protein with an active center consisting of 331 amino acids and a molecular weight of approximately 38,000. It catalyzes acyl transfer between proteins, leading to covalent cross-linking between proteins. TG enzyme significantly improves the foaming properties, emulsion stability, heat stability, water retention, and gelation ability of proteins. It is a widely used enzyme preparation in the food industry. Initially extracted from animals, TG enzyme is now mainly produced through microbial fermentation, making it suitable for industrial-scale production with high yields.

Advantages of TG Enzyme Applications

Wide Applicability: TG enzyme acts on protein molecules, making it applicable to any protein requiring improved processing characteristics. Its application is virtually unrestricted, especially as a processing aid in various meat products such as pork, fish, beef, meatballs, minced meat restructuring, fish paste products, sausages, ham sausages, plant-based protein meats, noodles, bread, tofu skin, cheese, and more. When used as a coagulant in soy products, it needs to be added within specified limits.

Strong Binding Capacity: TG enzyme catalyzes the formation of covalent bonds between proteins that are difficult to break under normal non-enzymatic conditions. Restructured meat treated with TG enzyme can maintain its properties unchanged. Currently, there is no substitute for TG enzyme under equivalent conditions.

Safety and Stability: The products catalyzed by TG enzyme have no adverse effects on the human body and fall within the scope of normal dietary consumption. TG enzyme is relatively stable under suitable temperature and pH conditions, adapting well to minor fluctuations in environmental conditions during food processing.

Interaction with Meat Proteins

The primary application scenario for TG enzyme is in meat products, where it significantly improves the texture. Its application in meat products depends on the protein content, and for products with a higher meat protein content, direct addition of TG enzyme can achieve the desired quality improvement. For products with lower protein content, the addition of protein slurry is often required to enhance the gel strength of exogenous proteins, and the synergistic effect with starch is also improved. Typically, an addition of 0.1%-0.2% of TG enzyme is sufficient to meet the requirements in meat products.

Interaction with Soy Protein

Soy protein isolate is referred to as a "protein companion" and is widely used in the food industry. After treatment with TG enzyme, soy protein isolate's gelation ability is enhanced, improving the quality of the target product. Additionally, enough TG enzyme catalysis can form a unique gel, enabling particle filling and simulation substitution.

Interaction with Wheat Protein

Wheat protein is a major component of gluten and a crucial factor affecting the quality of wheat products. In high-gluten systems, wheat products treated with TG enzyme can enhance the strength of the gluten network, preventing the product from collapsing and improving palatability. Currently, the use of TG enzyme in baked products is becoming more widespread.

The efficiency of transglutaminase enzyme depends on its contact with proteins. The low dispersibility and solubility of wheat protein reduce the catalytic efficiency of TG enzyme. Studies suggest that in a mixed system of wheat protein and soy protein, the improvement effect of TG enzyme increases with the addition of soy protein, showing a positive correlation with polarity and an inverse proportion to the wheat protein content. Therefore, pretreating wheat protein (reducing hydrophobic interactions) significantly enhances the effect of TG enzyme. Similarly, pretreating soy protein also improves the effectiveness of TG enzyme.

Catalytic capability and stability are two critical factors for enzyme preparations, and while TG enzyme demonstrates outstanding catalytic ability, its room temperature activity persistence and high-temperature processing stability need improvement. Furthermore, the TG enzyme market requires standardization as there is a lack of relevant standards. Products from different batches and manufacturers vary significantly, and some may contain substances such as phosphates and colloids, posing challenges for production enterprises. Nevertheless, it is undeniable that TG enzyme has injected considerable energy into the food industry, and with the increasing level of enzyme modification, its advantages become more apparent.