Optimization of hydrolysis conditions for the production of antioxidant peptides from fish gelatin using response surface methodology.

Fish skin gelatin was hydrolyzed with papain to produce antioxidant peptides. Response surface methodology (RSM) was applied to optimize the hydrolysis conditions (including enzyme to substrate ratio [E/S], hydrolysis time, and temperature). The highest degree of hydrolysis (DH) (50.1 +/- 1.1%) was obtained at an E/S of 2% at 56.8 degrees C, 2.11 h, and was not significantly different from the predicted values within a 95% confidence interval. The highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) (96.8 +/- 0.9%) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS(*+)) (9.80 +/- 0.11 mM Trolox [6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid]) radical-scavenging activities of fish gelatin hydrolyzates were obtained at an E/S of 3% at 52.1 degrees C, 2.65 h, and both DPPH and ABTS(*+) radical-scavenging activities were not significantly different from the predicted values 97.3% and 9.86 mM Trolox within the 95% confidence interval. Therefore, RSM is an efficient way to optimize fish gelatin hydrolysation and the resultant hydrolyzates show promise as antioxidant peptides. Practical Application: There is a growing interest in the use of fish gelatin as an alternative to mammalian gelatin. One potential use is as a source of widely acceptable functional compounds. In this study, a search for antioxidant peptides from fish gelatin prepared by an enzymatic method has been successfully done. This suggests that this is a practical way to obtain bioactive peptides.