冷冻诱导对大豆分离蛋白结构和聚集行为的影响

Effects of Freezing Treatment on Structure and Aggregation Behavior of Soybean Protein Isolate

为研究冷冻处理下大豆分离蛋白宏观结构性质的改变与其在冷冻过程中发生的微观聚集行为的关联性,该文以大豆分离蛋白溶液为原料,在-5、-20℃的条件下冷冻诱导后烘干再溶解,研究大豆分离蛋白溶液的浓度、冷冻诱导温度和时间对大豆分离蛋白聚集态的影响。通过溶解性、浊度等指标对大豆分离蛋白的聚集性行为进行分析,以电镜、稳定性动力学指数等指标对大豆分离蛋白的微观分子结构进行分析。结果表明,冷冻处理时间与大豆分离蛋白的溶解性大小成负相关,在-5℃冷冻处理5 d时大豆分离蛋白的溶解性达到最低,仅为(47.62±1.04)%,冷冻处理后大豆分离蛋白溶液的浊度与冷冻处理时的溶液浓度和冷冻时间呈正比关系,当浓度为5%的大豆分离蛋白溶液经冷冻处理后,蛋白溶液浊度达到最高0.79;随着大豆分离蛋白溶液浓度的增加,冷冻处理后蛋白中二硫键的含量也随之增加,当大豆分离蛋白溶液浓度为6%时,冷冻处理后蛋白中二硫键含量最大值为(26.54±0.78)μmol/g;随着冷冻诱导程度的加深,蛋白的溶解性降低,浊度变高,蛋白质发生聚集,导致其微观结构由稀疏到致密,变得更加稳定。

In order to study the relationship between the changes of macrostructure properties of soybean protein and the micro aggregation behavior during freezing,soybean protein isolate(SPI)solution was used as raw material,which was freeze induced at-5℃and-20℃and then dried and dissolved again.The effects of concentration of soybean protein solution,freezing induction temperature and time on the aggregation of soybean protein were studied.The aggregation behavior of SPI was analyzed by solubility,turbidity and other indicators.The micro molecular structure of SPI was analyzed by scanning electron microscope and stability kinetic index.The results showed that there was a negative correlation between the freezing time and the solubility of SPI.The solubility of SPI reached the lowest at-5℃for 5 days,which was only(47.62±1.04)%.The results showed that the turbidity of soybean protein isolate was the highest 0.79 at 5%SPI concentration;the content of disulfide bond increased with the increase of concentration of soybean protein isolate solution.When the concentration of soybean protein isolate solution was 6%,the maximum content of disulfide bond was(26.54±0.78)μmol/g;with the deepening of freeze-induced degree, the solubility of protein decreased, turbidity increased, protein aggregation, resulting in its microstructure from sparse to dense, becoming more stable.