余甘子多酚微波-热水浸提工艺的优化及其pH稳定性

Optimization of microwave-hot water extraction process of polyphenols from Phyllanthus emblica L.and its pH stability

以余甘子鲜果为原料,采用微波-热水浸提法提取余甘子多酚,通过单因素与正交试验优化最佳提取工艺,同时探究pH对提取液中多酚稳定性的影响。结果表明,余甘子多酚的最佳提取工艺为:微波功率640 W处理3 min,料液比1∶20(质量体积比),浸提温度50℃,浸提时间6 min,与传统的热水浸提相比,总酚提取量、黄酮提取量、DPPH自由基清除能力及FRAP铁还原能力分别提高了50.26%、21.41%、38.36%、18.38%。相关性分析结果表明,余甘子提取液中总酚、黄酮含量与DPPH自由基清除能力、FRAP铁还原能力之间有显著相关性(P<0.05)。pH稳定性研究结果表明,随着pH的增加,余甘子提取液中总酚含量、FRAP铁还原能力和DPPH自由基清除能力均先升高后降低,而黄酮含量在不同pH下差异不显著(P>0.05)。HPLC分析结果表明,不同酚类物质在不同的pH条件下稳定性不同,大多在酸性或弱酸性条件下较稳定。

The polyphenols were extracted from fresh Phyllanthus emblica L.by microwave-hot water extraction method.The optimal extraction process was optimized by single-factor and orthogonal experiments,and the effects of pH on the stability of polyphenols in the extraction solution were investigated.The results showed that the optimal extraction conditions of polyphenols were as follows:microwave power 640 W treatment for three minutes,solid-liquid ratio 1∶20,extraction temperature 50℃,extraction time six minutes.Compared with those under the traditional hot water extraction conditions,extraction amount of total phenol,extraction amount of flavonoids,DPPH free radical scavenging capacity and FRAP iron reducing capacity under the optional extraction conditions were increased by 50.26%,21.41%,38.36%and 18.38%,respectively.The results of correlation analysis showed that the contents of total phenols and flavonoids in the extraction solution were significantly correlated with DPPH free radical scavenging capacity and FRAP iron reducing capacity(P<0.05).The results of pH stability indicated that with the increase of pH,the total phenol content,FRAP iron reducing capacity and DPPH free radical scavenging capacity increased first and then decreased,while the flavonoids contents showed no significant difference at different pH values(P>0.05).HPLC analysis results showed that different phenols had different stability to pH,and most of them were stable under acidic or weakly acidic conditions.