桑叶蛋白的提取及EDTA-2Na对其浸提过程的影响

Mulberry Leaf Protein Extraction and EDTA-2Na Affect Its Extraction Process

为探索非变性原理提取桑叶蛋白的最佳条件,采用Na2HPO4-柠檬酸缓冲液提取桑叶蛋白,并进行蛋白质降解速度分析。通过4因素3水平正交试验对料液比、提取时间、提取温度、浸提液pH 4个因素进行优化,以叶蛋白得率、叶蛋白提取率为指标,得到提取桑叶蛋白的最佳工艺参数。结果表明,桑叶蛋白提取的优化工艺条件为:pH 7.6,料液比1:10,提取时间25 min,提取温度15℃。因新鲜叶片打浆时会破坏细胞壁,使细胞中的蛋白质在自溶酶的作用下发生分解,导致叶蛋白的提取率降低。为进一步提高桑叶蛋白的提取率,在最佳提取条件下,在打浆前向提取液中加入一定量的EDTA-2Na作为蛋白酶抑制剂,通过观察不同浓度EDTA-2Na作用下蛋白质的降解曲线,寻找EDTA-2Na的最适浓度,最终表明5 mmol/L的EDTA-2Na可最大限度降低浸提过程中蛋白质的降解。

In order to explore the optimum extracting conditions with non-denatured principle for leaf protein from mulberry, use NazHPO4-citric acid buffer to extract mulberry leaf protein and study the rate of protein degradation. Through 4 factors and 3 levels orthogonal experiments, 4 factors including material-liquid ratio, extracting time, extracting temperature and pH value were optimized. Protein yield and protein extraction rate were 2 indicators to find the most optimum processing parameters. The results showed that the most optimum conditions were as follows： pH 7.6, material-liquid ratio 1：10, extracting time 25 min, extracting temperature 15℃. As soon as the author beated fresh leaves the cell walls must be destroyed, the protein in the cell might decompose by the action of the autolysis enzyme, which would lead to a lower leaf protein extraction rate. Under the optimum conditions the author added a certain amount of EDTA-2Na as a protease inhibitor before beating so as to enhance the rate of protein extraction. It was found this optimum concentration by observing the protein degradation curve with different concentrations of EDTA-2Na. Uhimate it showed that during extraction, 5 mmol/L of EDTA-2Na could minimizes protein degradation.