花生蛋白酸法去酰胺条件的优化及其性质表征

为考察酸法去酰胺改性条件对花生蛋白改性效果和蛋白结构性质的影响,以去酰胺度、水解度以及二者比值为评价指标,分析硫酸浓度、花生蛋白质量浓度、反应时间、反应温度对去酰胺改性的影响,通过正交实验优化改性条件,并对改性花生蛋白的氨基酸组成、二级结构、微观结构与溶解性进行分析。结果表明:硫酸浓度、反应时间与反应温度是花生蛋白去酰胺改性的显著影响因素,同时,硫酸浓度与反应温度也会显著影响蛋白水解。花生蛋白去酰胺的最优条件是:0.30 mol/L硫酸,质量浓度5.5%花生蛋白溶液,85 ℃反应2 h,在此条件下,花生蛋白脱酰胺度为66.98%±0.54%,水解度为10.56%±0.27%,二者比例为6.34。去酰胺改性基本不影响花生蛋白的一级与二级结构,却会影响蛋白聚集形态,并显著(p<0.05)提高蛋白溶解性。

Condition optimization and properties characterization of peanut protein modified by acidic deamination

Peanut protein was modified by acidic deamination through degree of deamination, degree of hydrolysis and the rate of two degrees as evaluation indexes. Based on results of single factor experiments, concentration of sulfuric acid, reaction time and reaction temperature were optimized by orthogonal experiment. Moreover, the composition of amino acid, secondary structure, microstructure and solubility of modified peanut protein were analyzed. Results showed that the optimal conditions were 0.30 mol/L sulfuric acid, peanut protein concentration of 5.5%, reaction temperature of 85℃, 2 h reaction time, the degree of deamination, degree of hydrolysis and the rate of two degrees reached 66.98%±0.54%, 10.56%±0.27% and 6.34, respectively. Although the primary structure and secondary structure of peanut protein kept basically stable during acidic deamination, the morphology of protein aggregates changed, and the solubility of modified peanut protein improved notably.