响应面试验优化超声波-酶法提取绿豆皮黄酮类化合物工艺

采用Box-Behnken法优化绿豆皮黄酮类化合物提取工艺。应用超声波-酶法提取,考察超声功率、超声时间、加酶量、酶解时间对黄酮类化合物得率的影响,运用Design-Expert 8.0.5.0软件对绿豆皮黄酮类化合物得率的二次回归模型进行分析,确定最优提取工艺为超声功率192 W、超声时间28 min、加酶量0.24%、酶解时间40 min,在此条件下黄酮类化合物得率为(0.831±0.02)%(n=3),回归模型的预测值与实测值接近,该模型拟合较好;与在相同超声条件下,只用超声波提取相比,黄酮类化合物得率提高了18.54%。绿豆皮黄酮类化合物提取液在光谱条件下扫描,出现黄酮类化合物特征峰带,说明绿豆皮提取液中有黄酮类物质的存在;利用超高效液相色谱分析得出,发芽后绿豆皮中主要含有牡荆素和异牡荆素2种碳苷类黄酮化合物,分别占绿豆皮总黄酮含量的51.99%和45.42%。

Optimization of Ultrasonic-Assisted Enzymatic Extraction of Flavonoids from Mung Bean Coat

This research was conceived to optimize the ultrasonic-assisted enzymatic extraction of flavonoids from mung bean coat by using a Box-Behnken design with response surface methodology (RSM). A quadratic regression model was established using Design-Expert software version 8.0.5.0 based on a Box-Behnken statistical design to describe the yield of flavonoids as a function of ultrasonic power, ultrasonication time, enzyme dosage and hydrolysis time. The optimal extraction conditions were determined as follows: ultrasonic power, 192 W; ultrasonication time, 28 min; enzyme dosage, 0.24%; and hydrolysis time, 40 min. Under these conditions, the yield of flavonoids was experimentally measured to be (0.831 ± 0.02)% (n = 3). Good agreement was observed between the experimental and model predicted values, indicating good fitness. Compared with conventional ultrasonic extraction, the yield of flavonoids was improved by 18.54% using the combined procedure. Spectroscopic analysis showed the characteristic peaks of flavonoids, confirming the presence of these compounds in mung bean coat extracts. By ultra high performance liquid chromatography (HPLC) analysis, the coat of germinating mung beans mainly contained vitexin (51.99%) and isovitexin (45.42%).