影响蛋白质抗氧化活性的因素

Factors affecting antioxidant activities of proteins

以桃仁分离蛋白（PKPI）、大豆分离蛋白（SPI）、乳清分离蛋白（WPI）、酪蛋白（CA）为研究对象,以6-羟基-2,5,7,8-四甲基色烷-2-羧酸（Trolox）为对照,测定其DPPH自由基清除率,研究蛋白质浓度、温度、热处理时间、盐离子及其浓度、pH对蛋白质抗氧化活性影响。结果表明：蛋白质浓度0.05~2.00g/100mL,4种蛋白质抗氧化活性随其浓度的增大而增强。温度对蛋白质抗氧化能力有不同程度影响,且当温度为40,40,30,70℃时,PKPI、WPI、CA、SPI分别达到最大抗氧化活性。热处理时间对SPI、CA、PKPI抗氧化活性影响较小,但WPI抗氧化活性随热处理时间的延长而增大。NaCl、CaCl_2浓度0~10 mmol/L时,其对SPI、CA抗氧化活性影响较小;PKPI抗氧化活性受NaCl影响较小,而CaCl_2浓度增大降低了PKPI抗氧化活性;WPI抗氧化活性随着NaCl和CaCl_2浓度的增大而减小,且CaCl_2对WPI抗氧化活性影响大于NaCl。4种蛋白质抗氧化活性都受pH影响,pH 2.0时,其抗氧化能力高于pH 8.0。

The effects of protein concentration,temperature,heating time,salt ions and their concentration,and pH on the antioxidant activities of proteins including peach kernel protein isolates（PKPI）,soy protein isolates（SPI）,whey protein isolates（WPI）,casein（CA）were investigated by deterrnining their DPPH free radical scavenging capacities,and taking 6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid（Trolox）as the control.The results showed that at the concentrations of 0.05~2.00g/100 mL,the antioxidant activities of these proteins increased with the increase in the concentration;Temperature had different effects on proteins＇ antioxidant capacities with PKPI,WPI,CA,and SPI obtaining the best antioxidant activities at 40,40,30 and 70 ℃,respectively.Little effects of heating time were observed on SPI,CA and PKPI antioxidant activities at their optimal temperatures,respectively,while increasing heating time somehow improved the antioxidant activity of WPI at 40℃.0~10mmol/L,NaCl and CaCl_2 had less impact on the antioxidant activities of CA and SPI than that of WPI.Moreover,the effect of CaCl_2 on the decreased antioxidant capability of WPI was bigger than NaCl.NaCl had little influence on the antioxidant capacity of PKPI.However,increasing CaCl_2 reduced PKPI＇s antioxidant activity.These proteins＇ antioxidant activities were greatly influenced by pH.And at pH 2.0,their antioxidant capacities were higher than those at pH 8.0.