Enhancing the thermal stability of cowhide jelly through transglutaminase and agar

As an important local specialty dish, cowhide jelly suffers from issues such as poor thermal stability. Herein, cowhide jelly was modified using transglutaminase (TG) and agar, and the enhancement effect of the modification on the product's thermal stability and the underlying mechanism were investigated. Results showed that TG and agar significantly improved the melting point (from 29.16 °C to >80 °C), gel strength (from 84.23 g to 116.98 g), and chewiness (from 243.86 mj to 373.97 mj) of cowhide jelly. The covalent forces induced by TG, together with non-covalent forces triggered by agar, increased the cross-linking degree of cowhide jelly to 53.17%. Meanwhile, a large percentage of immobilized water was associated with the denser network structure formed after the cross-linking of TG, agar, and cowhide jelly. Furthermore, secondary structure determination showed that the β-sheet content of cowhide jelly increased (from 33.1% to 40.5%), indicating an improvement in its gelling properties. • Transglutaminase and agar promoted the melting temperature of cowhide jelly. • Both covalent and non-covalent crosslinking modes exist in modified cowhide jelly. • Agar induced non-covalent forces such as ionic bonds and hydrogen bonds. • Increasing β-sheet content of cowhide jelly improved water-holding capacity.