粗酶水相提取大豆油过程中蛋白酶解与油脂释放状态

Status of protein hydrolysis and oil release during crude enzyme-assisted aqueous extraction of soybean oil

为了考察粗酶水相提取大豆油过程中蛋白酶解和油脂释放状态,监测酶解过程中总油、总蛋白提取率以及蛋白相对分子质量变化,同时采用扫描电镜、考马斯亮兰与苏丹红Ⅲ染色显微观察技术研究酶解过程中油脂和蛋白在豆粉、水解液、乳状液中的分布状态。结果表明:随酶解时间延长,蛋白酶解程度加深,油脂释放量提升,水解蛋白中相对分子质量大于33 000 Da的多肽含量逐渐降低,而相对分子质量小于5 500 Da的短肽含量增加。酶解6 h时,总蛋白和总油提取率均达到最高,分别为90. 1%和94. 2%,此时蛋白水解液中短肽(<5 500 Da)含量最高,占49. 63%,相对分子质量大于33 000 Da的多肽仅占21. 15%。扫描电镜图显示由于酶解作用豆粉内的蛋白和油脂逐渐被分解和释放,原本充盈的细胞转变为空的残渣。光镜图显示,伴随豆粉酶解,水解液中蛋白含量逐渐增加,释放的油脂在水解液和乳状液中均有分布,随酶解时间延长油滴数量增加、粒径增大。

In order to investigate the status of protein hydrolysis and oil release during crude enzyme-assisted aqueous extraction of soybean oil,the extraction rates of total oil and total protein were monitored,and relative molecular weight of the protein was detected by gel chromatography.Meanwhile,scanning electron microscopy(SEM),light microscopy with Coomassie brilliant blue and Sudan redⅢstaining were used to reveal the distribution of oil and protein in soybean powder,hydrolysate and emulsion during the enzymolysis.The results showed that with the increase of enzymolysis time,the degree of protein hydrolysis deepened,and the oil release amount increased.The content of polypeptides with relative molecular weight higher than 33 000 Da gradually decreased,while the content of short polypeptides with relative molecular weight less than 5 500 Da increased.The highest extraction rates of total oil and total protein were obtained at enzymolysis time 6 h,which were 94.2%and 90.1%respectively,the content of short peptides(<5 500 Da)in protein hydrolysate was the highest,accounting for 49.63%,and the content of polypeptides with relative molecular weight higher than 33 000 Da was only 21.15%.SEM indicated that the protein and oil in soybean powder were gradually degraded and released by enzymolysis so that the original intact cells turned into empty residues.Light microscope pictures showed that with the hydrolysis of soybean powder,the protein content in hydrolysate increased progressively,and the oil released was distributed in hydrolysate and emulsion.The number and diameter of oil droplets increased with the extension of enzymolysis time.