Study Antioxidant and Functional Properties of Protein Hydrolysate Prepared from Silurus glanis Skin Using Papain Enzyme

Abstract

This study aimed to prepare protein hydrolysate from the hydrolysis of silurus glanis skin using papain enzyme, and study the functional properties and antioxidative activity. Crud protein extracted from the same fish skin used for comparesion. Fish skin were mixed with phosphate buffer (pH 7.0, 0.2 M) and placed on magnetic stirrer for 3, 6, 9, 12 hour at 45c° after addition of enzyme (1mg / 100gm skin).the crud protein extracted designated as (H) and the obtained hydrolysate as (P1, P2, P3 and P4). The percentages of soluble nitrogen and total nitrogen in skin were (0.14) and (3.15) % respectively.  The degree of hydrolysis for the obtained hydrolysates were (21.1) , (33.3) , (51. 1), 54.28))% for  P1, P2 , P3, P4 respectively. The results of  functional  properties  and  antioxidative activity  showed that the percentages of  water holding capacity were (3)%  for (H) and  (2, 2, 1, 1 %) for  P1, P2, P3 and P4 respectively. The solubility values were (12.8, 43.4, 64.7, 75, 92) %   for (H, P1, P2, P3 and P4) respectively. The emulsion capacity values were (20 ml) for (H) and (12, 13, 14, 16 ml) for P1, P2, P3 and P4 respectively.  It has been noticed that  the reducing power values were (0.591 -1.21) , (0.540 – 1.11 ) for BHT and citric acid respectively, and (0.403 – 0.754 ) for (H ) and (0.350 - 0.570) ,  (0.444 – 0.992) ,(0.526 – 0.642 ) , ( 0.449 – 0.769 ) for P1, P2 , P3 and P4 respectively .