枇杷叶多酚超声波辅助提取工艺优化及其抗氧性分析

目的]采用响应面法对超声波辅助提取枇杷叶多酚工艺条件进行优化,并评价其抗氧化性,为枇杷叶多酚的开发利用提供技术支持.方法]以干燥枇杷叶为原料,在单因素试验基础上,依据Box-Behnken原理选择提取时间、提取温度、料液比和乙醇体积分数4个因素进行响应面试验,确定枇杷叶多酚超声波辅助提取的最佳工艺条件,并与传统溶剂浸提法的提取效率进行对比;以羟基自由基和DPPH自由基的清除率为评价指标,对枇杷叶多酚的抗氧化性进行研究.结果]通过响应面设计分析得到超声波辅助提取枇杷叶多酚的最佳工艺条件为提取温度67℃、提取时间40 min、料液比1:25、乙醇体积分数60%,在此条件下得到枇杷叶多酚提取率为48.24 mg/g,与理论值48.79 mg/g相近;提取温度、提取温度与料液比及提取时间与料液比的交互作用对枇杷叶多酚提取效果影响显著(P<0.05).与传统溶剂浸提法比较发现,超声波辅助提取法得到的多酚提取率较高,且所需时间较短.枇杷叶多酚对羟基自由基和DPPH自由基的清除能力随枇杷叶多酚质量浓度的增大而不断增强,枇杷叶多酚质量浓度为20 μg/mL时,两种自由基的清除率分别为40%和56%.结论]响应面法优化的超声波辅助提取枇杷叶多酚工艺条件合理可行,与传统溶剂浸提法相比,超声波辅助提取法可明显提高多酚提取率;枇杷叶多酚具有较强的抗氧化性.

Ultrasonic assisted extraction of polyphenol from loquat leaves and its antioxidant activity

Objective]Ultrasonic assisted extraction of polyphenols from loquat leaves was optimized by response surface method,and antioxidant activity of polyphenols in loquat leaves was evaluated to provided technique support for the development and utilization of loquat leaf polyphenol.Method]According to the principle of Box-Behnken,the influ-encing parameters including extraction temperature,extraction time,solid-liquid ratio and ethanol concentration were op-timized using response surface method on the basis of single factor experiment. The optimum processing conditions of polyphenol extraction from loquat leaves by ultrasonic assisted method were determined,and the extraction rate was com-pared with that in traditional solvent-extraction method.The antioxidant properties of loquat leaf polyphenols were investi-gated with the scavenging rate of hydroxyl radical and DPPH as indicators.Result]Optimum processing conditions for ul-trasonic assisted loquat leaf polyphenol extraction obtained by the response surface design analysis were as follows:extrac-tion temperature was 67℃,extraction time 40 min,solid-liquid ratio 1:25 and ethanol concentration 60%.The total poly-phenol yield from loquat leaf was 48.24 mg/g in the optimal conditions,which was consistent with the predicted value (48.79 mg/g).Extraction temperature,interaction between extraction temperature and solid-liquid ratio,interaction be-tween extraction time and solid-liquid ratio had significant effects on loquat leaf polyphenol extraction(P<0.05). Com-pared with the traditional solvent extraction method,ultrasonic assisted extraction method was a extraction technology with high efficiency and shorter time.The scavenging capacity of loquat leaf polyphenol to hydroxyl radicals and DPPH free radicals strengthened with the increase of concentration of polyphenol in loquat leaf.When the concentration of loquat leaf polyphenol was 20 μg/mL,the scavenging rates of the two free radicals were respectively 40% and 56%.Conclu-sion]The processing conditions of ultrasonic assisted extraction of loquat leaf polyphenol are reasonable and feasible. Compared with traditional extraction method,ultrasonic assisted extraction can significantly improve the yield of polyphe-nol.Loquat leaf polyphenol has good antioxidant properties.