山羊乳酪蛋白酶解物制备及体外抗氧化活性研究

以自由基清除能力、金属离子螯合能力和抗脂质过氧化能力为指标，采用均匀试验研究山羊乳酪蛋白酶解物的制备及其体外抗氧化活性，并且比较自由基清除能力的方法。结果表明：山羊乳酪蛋白适宜的酶解工艺为在60g/kg的底物浓度下，中性蛋白酶和碱性蛋白酶的添加量分别为4000U/g和250U/g，45℃、pH7.5条件下酶解24h。山羊乳酪蛋白经酶解后其体外抗氧化活性显著增强。山羊乳酪蛋白酶解物 ·OH清除率的EC50值是其蛋白的3.59倍，ABTS＋ ·的清除能力是其蛋白的158.72倍，螯合Fe2＋的能力是其蛋白的5.44倍；在亚油酸体系中抗脂质过氧化能力强于TBHQ，与VE相当。清除 ·OH、DPPH自由基、O2－ ·和ABTS＋ ·的方法不能相互替代。

Enzymatic Preparation and Antioxidative Activity of Goat,s Milk Casein Hydrolysates in vitro

Our previously reported work has shown that one-step enzymatic hydrolysis with neutral and alkaline proteases allows the preparation of highly antioxidant goat,s milk casein hydrolysates. In this study, hydrolysis conditions for the preparation of goat,s milk casein hydrolysates by the method were optimized using uniform design based on radical scavenging activities against hydroxyl and DPPH free radicals. The results showed that hydrolysis for 24 h at 45 ℃, pH 7.5 and 60 g/kg substrate concentration with 4000 U/g neutral protease and 250 U/g alkaline protease proved optimal. The EC50 concentrations of the obtained hydrolysate for scavenging hydroxyl and ABTS+ · and chelating Fe2+ were 3.59, 158.72 times and 5.44 times higher than those of goat,s s milk casein, respectively. Moreover, this hydrolysate revealed stronger inhibitory effect on lipid peroxidation in linoleic acid model system and was equivalent to VE. The scavenging activities against hydroxyl, DPPH, superoxide anion and ABTS+ could not replace each other.