Agar hydrolysate (AH) from Gracilaria tenuistipitata was prepared using hydrogen peroxide (H₂O₂) scission and assessed as an antioxidative gel enhancer in surimi. Hydrolysis conditions were optimized via response surface methodology, considering time (0–3 h) and H₂O₂ concentration (2–4% w/w). Optimal hydrolysis (2.64% H₂O₂, 3 h) yielded a degree of hydrolysis (DH) of 30.49 ± 3.18% with high antioxidant activity. Both variables positively affected DH and antioxidant properties (P < 0.05). To test the potential of AH, agar/AH blends (100:0 to 50:50) were incorporated as 3% supplements in surimi gels, subjected to repeated freeze-thaw (F-T) cycles (0, 3, and 6 cycles). The 60:40 ratio significantly improved gel strength, reduced expressible moisture content, and prevented F-T-induced lipid oxidation (P < 0.05), while whiteness remained unchanged. Microstructural analysis confirmed the presence of finer gel networks and lower TBARS values (P < 0.05), indicating enhanced oxidative stability. These findings demonstrate that H₂O₂-generated agar hydrolysate, combined appropriately with native agar, serves as an effective natural multifunctional ingredient that simultaneously enhances gel properties and stabilities as well as provides antioxidative protection in surimi-based products. This approach advances sustainable production processes and enhances the utilization of fisheries resources.
Yarnpakdee et al. (Thu,) studied this question.