Abstract: Peanut antioxidant peptide was prepared by sequential hydrolysis of peanut protein powder with Viscozyme L followed by alcalase. The effects of heat, food additive, preservative, metal ion, sterilization, pH and low temperature treatment on antioxidant properties in vitro such as DPPH radical scavenging activity, reducing power, ferrous ion chelating ability and anti-lipid peroxidation were investigated. The results indicated that heat treatment and food preservative treatment were beneficial for increasing the antioxidant activity of peanut antioxidant peptide. The addition of tartaric acid or citric acid had considerable impact on the antioxidant activity of peanut antioxidant peptide. Nevertheless, the antioxidant activity remained at a stable level in the presence of sodium chloride or sucrose. Copper ion also had an obvious effect on the antioxidant activity of peanut antioxidant peptide. Various sterilization processes were beneficial to the scavenging of DPPH free radicals, reducing power, ferrous ion chelating capacity, but could reduce the inhibitory rate of lipid peroxidation. The reducing power, ferrous ion chelating capacity and anti-lipid peroxidation could be enhanced under alkaline conditions, whereas acidic conditions could reduce the ferrous ion chelating capacity and anti-lipid peroxidation. Low temperature treatment could reduce the antioxidant activity of peanut antioxidant peptide.

Key words: Viscozyme L, Alcalase, peanut antioxidant peptide, different treatment conditions, antioxidant activity