Characteristics and Antioxidative Activity of Gelatin Hydrolysates from Unicorn Leatherjacket Skin as Affected by Autolysis-Assisted Process

Autolysis-assisted process mediated by indigenous protease in combination with thermal hydrolysis and hydrolysis using papain was used for production of gelatin hydrolysate from skin of unicorn leatherjacket. Prior autolysis could enhance the yield and antioxidative activity of gelatin hydrolysates, especially when subsequent hydrolysis by 2% papain was implemented (AU + HP2.0). Hydrolysates possessed ABTS (2,2′-azinobis-[3-ethylbenzothiazoline-6-sulfonic acid]) radical and H2O2 scavenging activities as well as metal chelating activity. AU + HP2.0 and gelatin hydrolysate prepared using papain without prior autolysis (HP2.0) could retard oxidation in lecithin liposome system, and antioxidative activity of hydrolysates at 10.0 g/L was comparable to that of 0.1 g/L Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), in which the oxidation was almost completely inhibited. On the basis of size exclusion chromatography, antioxidative peptide in AU + HP2.0 had molecular weight of 2200 Da. Therefore, autolysis-assisted process showed the potential for the production of gelatin hydrolysates with enhanced antioxidative activity. Practical Applications The skin of unicorn leatherjacket contains heat-activated protease, which is capable of hydrolyzing gelatin. Autolysis-assisted process mediated by indigenous protease increased the yield and enhanced the antioxidative activity of gelatin hydrolysates from the skin. Moreover, gelatin hydrolysate can be produced directly from fish skin without prior gelatin extraction. The autolysis-assisted process could be promising for production of gelatin hydrolysate with antioxidative activity, in which the amount of external or commercial proteases could be less required and the indigenous protease was fully exploited.