酶辅助亚临界水提取高温豆粕蛋白及其性质研究

Extraction and Properties of Soy Protein from Heat-denatured Soy Meal Using Enzyme-Assisted Subcritical Water Treatment

摘要:

本文以高温豆粕为原料，采用β-葡萄糖苷酶辅助亚临界水提取大豆分离蛋白，对提取工艺进行优化，并对产物的理化、结构及抗氧化等性质进行表征。结果表明，高温豆粕在β-葡萄糖苷酶的作用下，糖苷型大豆异黄酮基本转化为生物活性较高的苷元型大豆异黄酮。亚临界水法显著提高了高温豆粕蛋白和大豆异黄酮的溶出率，强化了二者之间的疏水相互作用，获得了一种富集苷元型异黄酮的大豆分离蛋白。鉴于β-葡萄糖苷酶对大豆纤维部分酶解释放较多的还原糖和亚临界水所提供的高温高湿环境，蛋白发生去折叠，表面疏水性显著提高，形成可溶性蛋白聚集体且发生美拉德反应。高温豆粕蛋白中苷元型异黄酮的富集和接枝产物的形成使蛋白表现出良好的DPPH和ABTS自由基清除率。

Abstract:

The extraction process to obtain soy protein isolate (SPI) was optimized from heat-denatured soy meal (TDSM) by using enzyme-assisted subcritical water treatment. The physicochemical properties, structural properties, and antioxidant activity of SPI were investigated. The results showed that with the addition of β-glucosidase to TDSM, the isoflavone in glucoside form in TDSM was converted to the aglycone form, which showed higher biological activity. Subcritical water treatment increased the water solubilities of SPI and soybean isoflavone and strengthened the hydrophobic interactions between them, thus producing a form of aglycone-enriched SPI. While soybean cellulose was partially hydrolyzed into reducing sugar by β-glucosidase, high temperature and high humidity provided by the subcritical water treatment caused protein unfolding. Consequently, the surface hydrophobicity significantly increased, leading to the formation of soluble protein aggregates and causing the Maillard reaction. Enrichment of the isoflavone in the aglycone form in TDSM and the formation of grafting products may enhanced the DPPH and ABTS free-radical scavenging activities of the protein.