超声辅助酶法制备菜籽肽及其组成、 物理特性及结构分析Preparation of rapeseed peptides by ultrasound assisted enzymatic hydrolysis and analysis of its composition, physical properties and structure

为提高低温压榨菜籽饼的附加值和应用价值，采用石油醚对低温压榨菜籽饼进行脱脂，然后利用超声预处理分别辅助木瓜蛋白酶和碱性蛋白酶直接酶解制备菜籽肽，通过单因素试验探究超声功率、超声时间及酶添加量对菜籽肽得率的影响，通过响应面法优化超声辅助酶解工艺条件，并对所得菜籽肽的组成、物理特性以及结构进行分析。结果表明：碱性蛋白酶酶解的菜籽肽得率高于木瓜蛋白酶的；最佳超声辅助碱性蛋白酶酶解工艺条件为酶添加量12 289.79 U/g、超声时间21.82 min、超声功率306.56 W，该条件下菜籽肽得率为55.19%；最佳条件下所得菜籽肽的分子质量范围为88.02~1 290.00 Da，其中9840%的菜籽肽分子质量小于500 Da，相较于未超声辅助酶解，所制备的菜籽肽氨基酸含量增加，粒径变小，Zeta电位绝对值变大，二级结构中α-螺旋和β-折叠含量增加，β-转角含量减少，二级结构更有序、稳定。综上，超声辅助酶法不使用有机溶剂，环境友好，且产品品质较好，可以用于高效提取菜籽肽。 To enhance the added value and application potential of low temperature pressed rapeseed cake, the low temperature pressed rapeseed cake was defatted with petroleum ether, then ultrasound pretreatment was employed to assist in the direct enzymatic hydrolysis using both papain and alkaline protease to prepare rapeseed peptides. Single-factor experiments were conducted to investigate the effects of ultrasound power, ultrasound time, and enzyme addition amount on the yield of rapeseed peptides, followed by optimization of process conditions using response surface methodology. The composition, physical properties and structure of the obtained rapeseed peptides were analyzed.The results indicated that the yield of rapeseed peptides obtained by alkaline protease hydrolysis was higher than that of papain. The optimal process conditions were alkaline protease addition amount 12 289.79 U/g, ultrasound time 21.82 min, and ultrasound power 306.56 W. Under the optimal conditions, the yield of rapeseed peptide was 55.19%, and the molecular weight of rapeseed peptides ranged from 88.02 Da to 1 290.00 Da, with 98.40% of rapeseed peptides less than 500 Da. Compared with the product without ultrasound assisted enzymatic treatment, the content of amino acid of rapeseed peptides increased, the particle size decreased, the absolute value of Zeta potential increased, α-helix and β-folding in the secondary structure increased, β-angle decreased, and the secondary structure was more orderly and stable. In conclusion, ultrasound assisted enzymatic methods does not use solvent, is environmentally friendly and has good product quality, and can be used for the efficient and direct extraction of rapeseed peptides.