Transglutaminas
transglutaminas catalyzes the formation of ε- (γ- glutamine) lysine bonds (isopeptide bond) within or between milk protein molecules. Due to the cross-link within and between protein molecules, their functional properties are improved.
The reaction mechanism is as follows:
Cross-link between Gln residue and Lys residue
The jelly-like system of yogurt is built on weak non-covalent bonds, primarily maintained by hydrogen bond, but whey protein is difficult to form jelly-like system. Such jelly-like system is very fragile, for its texture gets broken easily and causes serum precipitation during the process of stirring and storage, thus decreasing product value.
Thanks to the cross-link of milk proteins (including caseins and serum proteins) occur within or between molecules catalyzed by transglutaminas, a more stable covalent bond is created.
As a result, transglutaminas helps form a stronger network structure, enhance the hydration function of gel, moisture in the network structure cannot be easily precipitated, making the yogurt taste more creamy and look thicker in texture, and reducing serum precipitation.