Impact of Eggshell-Derived Calcium Oxide on Protein Cross-Linking and Gel Properties of Giant Snakehead (Channa micropeltes) Surimi

This study investigated the effects of calcium oxide (CaO) derived from eggshells on the gelation properties of surimi prepared from giant snakehead (<i>Channa micropeltes</i>). Surimi gels were enriched with CaO at concentrations of 0, 2, 4, 6, 8, and 10 µmol/100 g, and their physicochemical, rheological, and structural characteristics were evaluated. The optimal CaO concentration (6 µmol/100 g) significantly enhanced gel strength by 48.2%, breaking force by 26%, and deformation by 18% compared to the control (<i>p</i> < 0.05). Expressible moisture content decreased from 16.88% to 7.12%, while total sulfhydryl groups were reduced to 5.17 µmol/100 g. Rheological analysis revealed increased storage modulus (G') and loss modulus (G″), indicating enhanced gel elasticity and viscosity during thermal processing. Scanning electron microscopy (SEM) demonstrated the formation of a compact, uniform gel network with fine pores at the optimal CaO concentration. SDS-PAGE analysis confirmed that CaO promoted transglutaminase (TGase) activity and TGase catalyzes the formation of cross-links between myosin heavy chain (MHC) and disulfide bonds. These results demonstrate the potential of eggshell-derived CaO as a sustainable, cost-effective additive to enhance surimi gel quality.