Abstract:

Superoxide dismutase (SOD) was added as a functional ingredient to milk to prepare an SOD-supplementedyoghurt. Changes in the SOD activity of the supplemented yoghurt during storage 4 ℃ and the stability under simulatedgastrointestinal digestion were investigated. The results showed that the enzyme retained 84.5% of its original activity after6 days of storage, and 64% after 14 days. When exposed to simulated gastrointestinal fluid at pH 2 for 3 h, SOD and itssupplementation in yoghurt, although maintaining only 0.1% and 8.7% of the original activity, respectively, showed higheractivity levels in simulated gastrointestinal fluids at pH 3 and 4, reaching 50.4%, 60.7%, 65.4% and 84.4% of the originalactivity, respectively. After 4 h incubation in artificial intestinal fluid, the residual activity was 44.8% for SOD solution.Exposure to bile salt solutions at different concentrations for 4 h resulted in a residual enzyme activity of over 87.4%. Aftercontinuous digestion in the artificial gastric fluid and artificial intestinal fluid, the residual activity was 15.4% and 72.4% forSOD solution and SOD-supplemented yogurt, respectively. Therefore, SOD has excellent tolerance to artificial gastric fluidat a pH level above 3, artificial intestinal fluid, and bile salt environment. In contrast, it when added to yoghurt, it has higherstability to simulated gastrointestinal digestive fluid.

Key words: superoxide dismutase (SOD), SOD-supplemented yogurt, gastrointestinal digestive fluid, stability