Improving the physicochemical properties of microbial transglutaminase-induced fish gelatin gels by incorporating sanxan as a novel way

Abstract

Fish gelatin (FG) is recognized as a promising alternative to mammalian gelatin sources. However, some undesirable physicochemical properties of FG such as weak texture, poor rheology, and poor thermostability limit its application. This study explored the effect of sanxan (SX) on the FG gelling behavior under conditions induced by microbial transglutaminase (MTGase). It was observed that the water-holding capacity, gel strength, and viscoelastic characteristics of FG gel were enhanced by adding SX. Meanwhile, thermogravimetric analysis exhibited that the thermostability of FG was also improved. Zeta potential measurements suggested the presence of electrostatic interactions between SX and FG. FTIR spectral analysis revealed that the added SX significantly affected the secondary structure of FG and verified the presence of both hydrogen bond and electrostatic interactions between FG and SX. The added SX reduced the α-helix content and increased the β-sheet content, leading to orderly aggregation and protein unfolding. This resulted in the formation of a dense and uniform FG-SX composite gel network. Additionally, intrinsic fluorescence, surface hydrophobicity, and protein solubility analyses revealed that hydrophobic interactions are crucial in the forming the FG-SX composite gel. These findings offer new insights into the potential of SX as a natural and innovative gel modifier to enhance the functionality of enzyme-induced protein gel-based foods.