Antioxidant activities of pepsin hydrolysates of water‐ and salt‐soluble protein extracted from pork hams

The objective of this study was to evaluate the antioxidant activities of pepsin‐digested water‐soluble protein (WSP) and salt‐soluble protein (SSP) extracted from pork ham. WSP and SSP were hydrolysed by pepsin for 2–10 h with 2‐h increments. The protein hydrolysates by pepsin were analysed by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis, and reducing power of the hydrolysates was measured. In addition, antioxidant activity of the hydrolysates was determined using linoleic acid emulsion system. Protein bands with molecular weight higher than 7 kDa in WSP and SSP were completely hydrolysed by pepsin after 2 h of digestion time. WSP hydrolysates (WSPH) and SSP hydrolysates (SSPH) had higher ferric reducing power than controls (WSP and SSP without pepsin digestion). Reducing powers of WSPH were higher than those of SSPH, regardless of digestion time. The oxidative activity of linoleic acid was predominantly inhibited by the addition of WSPH and SSPH, especially 0.5% protein hydrolysate. These results indicate that several functional peptides of pork protein digested by pepsin might have antioxidant activity, and thus they may be used as an antioxidant agent in muscle food system.