Stability of an antioxidant peptide extracted from Jinhua ham.

The effects of NaCl, temperature, pH, light intensity and a simulated gastro-intestinal digestion were assessed to determine the stability of antioxidant peptides extracted from Chinese Jinhua ham. Antioxidant peptides showed good stabilities when NaCl content was less than 6%, temperature was lower than 60 °C and they were not exposed to light directly. However, the antioxidant peptides lost antioxidant activities rapidly under alkaline condition. The results of a simulated two-stage digestion system showed that antioxidant activity increased with pepsin treatment but declined with further hydrolysis with trypsin. Pepsin was effective to hydrolyze peptides into smaller fractions leading to the increased exposure of internal hydrophobic amino acids, but trypsin could hydrolyze peptides into more free amino acids resulting in the decline in surface hydrophobicity which affected antioxidant activity of peptides. These suggest that antioxidant peptides extracted from Jinhua ham could maintain their antioxidant activity under the proper conditions.