Fortification of surimi gels by tuning the synergetic effect of multiple enzyme-related factors

Enzymes play critical roles in surimi gelation and gel physiochemical properties. Understanding and thus tuning enzyme-related multiple factors are warranted for preparing high-quality surimi products with satisfactory textural profiles. In this study, three enzyme-related factors, i.e., Ca2+ required for endogenous TGase activation, whey protein concentrates (WPC) as an endogenous proteases inhibitor, and MTGase capable of catalyzing protein crosslinking, are explored regarding their gel-enhancing performance. Ca2+, WPC and MTGase at their optimal concentrations (3.5%, 5% and 1%, respectively) are introduced into surimi gels together, leading to significant increases in the hardness and WHC of the obtained surimi gels by 156% and 25%, correspondingly. Next, a mechanism underpinned by the synergetic effect of Ca2+, WPC and MTGase on improving surimi gel properties is proposed. Ca2+ could activate endogenous TGase for proteins crosslink, whereas WPC avoids the proteolytic disintegration of gel networks by inhibiting endogenous proteases, and MTGase catalyzes the ε-(γ-glutamyl) lysine linkages between ε-amino groups of lysine residues and γ-carboxyamide groups of glutamine residues on myosin heavy chains. These beneficial effects then induce a well-developed three-dimensional gel network. Collectively, we propose and validate a new strategy based on the major enzyme-related factors during gelation to improve surimi gel properties, which may provide useful guidelines on tuning the textural properties of meat-based products in the food industry.