用发酵法制备桑叶蛋白的工艺优化和产品的体外消化率测定

为了多元化开发利用桑叶蛋白质资源,将桑叶粉用枯草芽孢杆菌发酵制备桑叶蛋白。以桑叶蛋白得率为响应值,通过Plackett-Burman试验设计、最陡爬坡试验和Box-Behnken试验设计对桑叶发酵条件进行优化,并对发酵后桑叶蛋白的体外消化能力进行评价。结果表明,桑叶粉质量浓度、装液量、蔗糖质量浓度和发酵时间对桑叶蛋白得率具有显著影响(P<0.05),其影响大小依次为桑叶粉质量浓度>装液量>蔗糖质量浓度>发酵时间,发酵最优条件为桑叶粉质量浓度2.64mg/mL、装液量105 mL、蔗糖质量浓度22 mg/mL、发酵时间45.1 h。在此优化条件下,桑叶蛋白得率的预测值为16.43%,验证值为16.29%,试验结果重现性良好,建立的桑叶蛋白得率与主要发酵条件因子的数学回归模型可靠。体外消化试验表明,该方法制备桑叶蛋白的体外消化能力得到显著提高(P<0.05),体外消化率比发酵前提高了4.29个百分点。

Optimization of Technology for Preparation of Mulberry Leaf Protein by Fermentation and Determination of in Vitro Digestibility of the Prepared Product

In order to develop and utilize the resources of mulberry leaf protein,protein product was prepared by using Bacillus subtilis fermentation method.Taking yield of mulberry leaf protein as response value,the conditions for mulberry leaf fermentation were optimized through Plackett-Burman,steepest ascent experiment and Box-Behnken experimental design,and in vitro digestibility of mulberry leaf protein after fermentation was evaluated.The results showed that mulberry leaf powder mass concentration,loading volume,sucrose mass concentration and fermentation time had significant influence on yield of mulberry leaf protein(P<0.05).The influence of each factor on yield of mulberry leaf protein was in the order of mulberry leaf powder mass concentration>loading volume>sucrose mass concentration>fermentation time.The optimized fermentation conditions were as follows:mass concentration of mul-berry leaf powder 2.64 mg/mL,loading volume 105 mL,mass concentration of sucrose 22 mg/mL,and fermentation time 45.1 h.Under these optimal conditions,the yield of mulberry leaf protein was 16.43% in theory,and the actual value was 16.29%.The result was reproducible and the established mathematical regression model for yield of mulberry leaf protein and major factors of fermentation condition were reliable.Digestion experiment showed that the in vitro digestibility of mulberry leaf protein after fermentation was significantly increased(P<0.05),being 4.29 percentage points higher than that before fermentation.