采收期对膜荚黄芪叶茶生物活性成分的影响

Effect of different harvest time on bioactive components of leaf tea in Astragalus membranaceus

膜荚黄芪(Astragalus membranaceus)是药食同源黄芪的基原植物之一,成药期枝叶繁茂,为开发中药资源功能叶产品,在其成药栽培期每15 d采摘1次叶片,按绿茶加工工艺制成叶茶,系统测定不同采收期叶茶内生物活性成分,旨在探寻膜荚黄芪叶茶的最佳采收期和资源利用潜力。结果表明:叶茶生物活性成分随采收时间的不同而异,黄酮类和多酚类含量均随采收期的延后先升高后下降,总黄酮含量分别为:6月30日(17.06%)>6月15日(16.62%)>5月30日(16.53%)>7月15日(15.73%);4个采收期多酚含量依次为:4.49%、5.63%、5.50%、5.31%;多糖和水浸出物、醇浸出物含量均随采收期延后显著提高,含量依次为:5月30日(4.98%、47.16%、47.01%)<6月15日(6.00%、48.79%、47.40%)<6月30日(6.90%、49.08%、47.70%)<7月15日(7.80%、50.29%、48.36%)。随采收时间延后黄芪叶茶总抗氧化生物活性成分先升高后下降,营养成分含量持续升高,即抗氧化生物活性成分:6月30日(29.46%)>7月15日(28.83%)>6月15日(28.25%)>5月30日(26.00%),营养成分7月15日(98.65%)>6月30日(96.78%)>6月15日(96.19%)>5月30日(94.17%)。浸出物与多糖和多酚含量均呈正相关,与黄酮含量呈负相关。说明中药资源膜荚黄芪叶茶是良好的药食同源功能产品,具有很大的开发利用潜力,以6月30日至7月15日为最佳采收期。

Astragalus membranaceus(Fisch.)Bge.is one of the original plant species of Astragalus,which is luxuriant in the medicine formation year.In order to explore the potential utilization of traditional Chinese medicine resources and the optimal harvest time,the plant leaves were harvested on four occasions at an interval of 15 days between two consecutive harvests.Leaves were then made into leaf tea according to the green tea processing technology.The bioactive components in leaf tea harvested at four different time were measured.The results showed that the bioactive components of leaf tea varied along the harvest time,with the total flavonoid content and total phenolic content being initially increased followed by a decrease along the harvest time.The total flavonoid content of leaf tea harvested at different time was ranked in the order of the following:June 30(17.06%)>June 15(16.62%)>May 30(16.53%)>July 15(15.73%);while their corresponding total phenolic content was 4.49%,5.63%,5.50%and 5.31%.The polysaccharides content,water extract and alcohol extract increased significantly with the delay of harvest time.The polysaccharides content,water extract and alcohol extract were ranked in the order of the following:on May 30(4.98%,47.16%,47.01%)<on June 15(6.00%,48.79%,47.40%)<on June 30(6.90%,49.08%,47.70%)<on July 15(7.80%,50.29%,48.36%).With the delay of harvest time,the total antioxidant bioactive components in leaf tea of A.membranaceus initially increased followed by a decrease,while the content of nutritional components continued to increase.The antioxidant bioactive components were ranked in the order of June 30(29.46%)>July 15(28.83%)>June 15(28.25%)>May 30(26.00%),and the nutritional components were in the order of July 15(98.65%)>June 30(96.78%)>June 15(96.19%)>May 30(94.17%).The content of polysaccharides and total phenolic in the extracts of leaf tea were positively correlated with the content of total flavonoid.Our results show that A.membranaceus leaf tea is a good functional product of traditional Chinese medicine resources,which has great potential for further development and utilization.The best harvest time would be from June 30 to July 15.