Abstract:Objective: To guide the rational use of sturgeon skin resources, this study aimed to compare the production efficiency and bioactivity between the gelatin-peptide complex (GPC) made from sturgeon skin by the method of pyrolysis and enzymatic hydrolysis, respectively. Methods: Using sturgeon skin as raw material and GPC yield as an indicator, pretreatment condition of sturgeon skin and the preparation of GPC by pyrolysis were optimized. On the other side, using the GPC with given maximum molecular weight as substrate, and trichloroacetic acid soluble oligopeptide (TCA-SP) was used as an index, the enzymatic hydrolysis efficiency of several kinds of protease on this substrate was investigated. Finally, the effects of GPCs prepared by pyrolysis and protease hydrolysis, with the highest TCA-SP yield, on the viability of normal and D-galactose-induced oxidative damage PC12 cells was compared. Results: Alkali treatment did not contribute significantly to the extraction of GPC from sturgeon skin, while acid treatment did. The optimized condition for acid treatment was incubating the sturgeon skin at 0.25 mol/L HCl for 6 h. The most suitable conditions for GPC preparation by high-temperature pyrolysis were found at 100 ℃ for 2 h, with a highest GPC and TCA-SP yield of 34.72% and 31.22%, respectively. The GPC obtained by low-temperature pyrolysis at 60 ℃ for 1 h had the highest viscosity and the lowest TCA-SP, suggesting it had maximum molecular weight and relatively complete structure. GPC-60 ℃-1 h was then used as the substrate to be hydrolyzed by several proteases respectively. A highest TCA-SP content of 28.74% was observed in the hydrolysate of neutral protease for 0.5 h. GPC-100 ℃-2 h and GPC-N-0.5 h had no cytotoxic effect on normal PC12 cell viability at 50-1 000 μg/mL. And both had a certain protective effect on PC12 cells against D-galactose-induced oxidative damage at 12.5-200 μg/mL, and there seemed no significant difference between them. Conclusion: The TCA-SP content in the GPC obtained by high-temperature pyrolysis was similar to that prepared by neutral enzymatic hydrolysis, and their protective effect on PC12 was also similar.