生物解离大豆过程中形成的乳状液结构

以不同酶解时间(1、2、3 h)、不同酶添加量(1%、2%)生物解离大豆过程中形成的乳状液为研究对象,探究乳状液中乳滴聚集机制、结构特征及分子间相互作用。通过乳状液中蛋白水解度、显微镜观察、Zeta电位、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)、荧光色谱等指标的测定发现:经过蛋白酶酶解,乳状液中蛋白水解度在7%左右;生物解离使乳状液蛋白被酶解成分子质量较小的肽段,乳状液油脂与蛋白之间的亲和力降低,乳滴出现聚集,Zeta电位绝对值减小;SDSPAGE条带上出现了由二硫键引起的大分子质量的蛋白聚集体;另外,乳状液荧光光谱中,乳状液相对于相同酶解条件下大豆分离蛋白荧光强度明显减弱,可能是由磷脂的存在、蛋白质-油脂之间的相互作用及蛋白质聚集体导致。

Structural Study on Emulsion Formed during Enzyme-Assisted Aqueous Extraction from Soybean Oil

In this study, the emulsion formed during enzyme-assisted aqueous extraction of soybean oil was investigated at different hydrolysis times (1, 2, and 3 h) and enzyme dosages (1% and 2%). The mechanism of action of oil droplets in the emulsion was elucidated to explore the structural features and intermolecular interactions. The degree of hydrolysis (DH), microscopic observation, zeta-potential, fluorescence spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles were determined. The results showed that the DH of the emulsion was about 7%. As a result, the protein in the emulsion was broken down into small peptides, resulting in reduced affinity between oil and protein, droplet aggregation and decreased absolute value of zeta potential. Large protein aggregates linked by disulfide bonds appeared on the SDS-PAGE. In addition, the fluorescence intensity of the emulsion was obviously weakened as compared to soybean protein isolate (SPI) under the same hydrolysis conditions, which may be attributed to the presence of phospholipids, the interaction between tryptophan residue and oil and the disulfide-linked aggregates.