Combined effects of gelatin extraction methods and hydrolysis protease types on the functional properties of tilapia scale gelatin hydrolysates

Summary The combined effects of gelatin extraction methods and protease types on the functional properties of tilapia scale gelatin hydrolysates (TSGH) were investigated. The tilapia scale gelatin (TSG) was extracted after acid/base pretreatments, respectively, and then hydrolysed with different proteases to produce TSGHs. The degree of hydrolysis and the content of trichloroacetic acid soluble peptide were increased with hydrolysis time, while the content of β-sheet was decreased significantly with the hydrolysis time ( P < 0.05). The emulsification stability of acid protease hydrolysate (APH) was higher than that of neutral protease hydrolysate (NPH) and alkaline protease hydrolysate (ALPH). All samples showed good resistance to oxidation: DPPH (20%–64.66%), ABTS (29.08%–63.04%), and iron reducing power (0.017–0.499). The hydrolysates obtained from the base-pretreated TSG showed higher antioxidant properties than acid-pretreated TSG. The antioxidants of different protease hydrolysates are ranked by ALPH > NPH > APH. In conclusion, gelatin extraction methods and its hydrolysis conditions had influences on the functional properties of TSGH, and the study of the processing of marine biological wastes is of great significance in realising their high-value utilisation and reducing the burden on the environment.