Effect of Antioxidative Peptide Components of Kidney Bean Protein on Thermal Oxidation Stability of Soybean Oil

In order to explore the antioxidant effects of the British red kidney bean protein antioxidant peptide components and their effects on soybean oil thermal stability, the antioxidant peptides components of different molecular weights were added to the soybean oil and oxidized by Schaal oven method at 63 ℃ for 15 day. The effects of antioxidant peptides on the peroxide value, acid value, p-anisylamine, carbonyl value indexes of soybean oil were studied, and the oxidation stability of soybean oil was evaluated. The results showed that, from 0 to 15 day, the peroxide values of SO (peptide-free oil), SO-h₁ (oil containing peptide less than 1000 Da) and SO-h₂ (oil containing 1000~3000 Da peptide) increased from 0.50 to 2.91, 1.48 and 1.57 mmol/kg, respectively, the acid value increased from 0.19 to 0.41, 0.37 and 0.38 mg/kg, the p-anisidine value increased from 2.34 to 9.96, 8.06 and 9.75 mg/kg, and the carbonyl value increased from 5.59 to 14.53, 11.87 and 11.92 meq/kg, respectively. The increasing range of SO was the largest, and the increasing range of SO-h₁ was the smallest, and the above results were significantly different (P<0.05). Thus, the oxidant index of the soybean oil increased with the extension of the oxidation time of soybean oil, which led to the thermal stability of the soybean oil decreasesed．The antioxidant activity of the antioxidant peptide components was correlated with the molecular weight, the kidney bean antioxidant peptide component of less than 1000 Da and 1000～3000 Da were the most effective. This research would provide the theoretical basis for the further application of British red kidney bean protein antioxidant peptide components.