Abstract: In order to optimize the extraction process of polyphenols from sweet potato leaves using a ultrasonic assisted method. Box-Behnken response surface analysis method was used on the basis of single-factor experiment. The differences of polyphenol content in different varieties of sweet potato leaves and roots were compared. The results showed that the optimum extraction conditions of sweet potato leaves polyphenols were as follows: ethanol concentration fraction of 73%, extraction time of 35 min, and liquid-material ratio of 40 mL·g^-1. Under this condition, the polyphenol content of oven-drying sample of the variety Xushu 36 sweet potato leaves was 32.92±0.093 mg·g^-1 (RSD=0.21%). The content of polyphenols in leaves and tubers of 12 sweet potato cultivars was determined and analyzed. That there was a significant difference in the polyphenol content of sweet potato. Among them, the contents of polyphenols with in leaves and tubers of the variety Xuzishu 6 were the highest. The content of polyphenols in different flesh color sweet potato tubers was roughly purple meat type > red (yellow) meat type > white meat type. The results of this study provide a theoretical basis for the development and utilization of the leaves of sweet potato.

Key words: sweet potato, polyphenols, response surface analysis, ultrasonic extraction, cultivar variation

摘要： 为优化甘薯叶片多酚提取工艺,利用超声波辅助法提取甘薯叶片中的多酚,以多酚得率为指标,考察乙醇体积分数、超声提取时间和液料比对多酚提取效果的影响。在单因素试验的基础上,通过Box-Behnken响应面分析法研究甘薯叶片中多酚的最佳提取工艺条件,并比较不同品种甘薯叶片和块根中多酚含量差异。结果表明,甘薯叶片多酚的最佳提取工艺条件为:乙醇体积分数73%、超声时间35 min、液料比40 mL·g^-1,在此条件下徐薯36号甘薯叶片烘干样多酚得率为32.92±0.093 mg·g^-1(RSD=0.21%)。据此分析测定了12个品种甘薯叶片和块根多酚含量,发现甘薯多酚含量存在明显的品种间差异,其中徐紫薯6号叶片和块根中的多酚含量均最高。不同肉色甘薯块根多酚含量大致为紫肉型>红(黄)肉型>白肉型。本研究结果为甘薯的开发利用提供了一定的理论依据。

关键词: 甘薯, 多酚, 响应面分析, 超声提取, 品种间差异