选择性水解对大豆分离蛋白表面性质的影响

Effect of Selective Hydrolysis on Surface Properties of Soybean Protein Isolate

通过控制温度与p H,研究胃蛋白酶在不同处理条件下对大豆分离蛋白水解模式的影响及产物乳化性和起泡性的影响。结果表明:p H2.0,37℃时,选择性水解11S组分;p H3.8,70℃时,选择性水解7S组分;p H2.0,70℃时,11S组分与7S组分均被水解;p H3.8,37℃时,11S组分与7S组分几乎不发生水解。水解产物乳化特性显示11S被选择性水解后,乳化活性与乳化稳定性均显著提高,分别从0.724,25 min提高到1.716,38.2 min;7S被选择性水解的蛋白乳化活性没有改善,但乳化稳定性提高到29.6 min;而11S与7S均被水解后,蛋白乳化活性提高到1.417,乳化稳定性则较差。各水解产物的起泡能力与泡沫稳定性均显著提高,其中水解产物在p H4.5处上清的起泡能力最强,接近未水解蛋白的4倍,7S被水解的蛋白在p H4.5处上清的泡沫稳定性最好,约为未水解蛋白的1.2倍。

Since 7S and 11 S fractions in a soy protein isolate have many differences in chemical,physical and functional properties,there would be different effects on protein properties of selective hydrolysis of 7S and 11 S. During the experiments,SPI was treated with controlled p H and temperature to make the specific component denatured,and the denatured component would be hydrolyzed by pepsin. The results revealed that when the temperature was 37℃,p H was 2. 0,11 S was selectively hydrolyzed; and 7S was selectively hydrolyzed under the condition of 70℃,p H3. 8. When the temperature was 70℃,p H was 2. 0,both 11 S and 7S were hydrolyzed. All of the hydrolysis reactions were hard to happen at 37℃,p H3. 8. The determination of emulifying properties of hydrolysates showed the hydrolysis of 11 S could significantly improve emulsifying activity and emulsifying stability and make them increased to 1. 716,38. 2 minutes; The hydrolysis of 7S could improve emulsifying stability to29. 6 minutes,while emulsifying activity had no improvement; The non-selective hydrolysis of 11 S and 7S could improve emulsifying activity to 1. 417,but emulsifying stability was worsen. Foaming capacity and foam stability of the hydrolysates were both significantly improved. All of the supernatant from hydrolysates centrifuged at p H4. 5 had more excellent foaming ability which was 4 times as high as unhydrolyzed protein. The foam stability of supernatant from protein with 7S component hydrolyzed was the best,which was 1. 2 times as high as unhydrolyzed protein.