Innovation in the food industry using microbial transglutaminase: Keys to success and future prospects

Transglutaminase (TG) catalyzes cross-linking between the γ-carboxyamide groups of glutamine residues and the ε-amino groups of lysine residues in polypeptide chains, yielding ε- (γ-glutamyl) lysine (G-L) bonds. By forming a network structure in the protein via G-L bonds, it is possible to increase the viscosity of protein solutions or to cause gelation. Nearly thirty years have passed since microbial TG (MTG) appeared in the food enzyme market. Since the start of research and development, MTG has been used in fishery products such as kamaboko (boiled fish paste), meat products such as sausages, milk products such as yogurt, processed-soybean products such as tofu, and wheat products such as bread and noodles. MTG has provided effects such as adding new functions and reducing waste in food applications. The purpose of this review is to describe not only the history of research and development of TG but also the key aspects that have facilitated the great success of this process as a technology for enzymatically modifying protein-containing foods.