超声辅助室温冲泡绿茶的条件筛选和品质分析

Optimization of Conditions for Ultrasound-Assisted Brewing of Green Tea in Water at Room Temperature and Quality Analysis of Tea Infusion

为缩短绿茶室温冲泡的时间并获得较优品质,实验利用超声作为辅助,通过感官审评和主要滋味组分及香气组分的分析,筛选优化冲泡条件,并比较其与标准沸水冲泡的品质差异。结果表明:超声辅助室温冲泡绿茶的优化条件为投茶量5 g、茶水比1∶30(g/mL)、超声时间10 min,该条件下冲泡的绿茶与标准沸水冲泡相比,水浸出物、茶多酚和咖啡碱含量较低,氨基酸含量较高;二者绝大部分香气组分相同,但室温冲泡的缺少了辛醛、反-2-辛烯醛等具有不愉快脂肪气味的物质,增加了α-芳樟醇、己酸-反-2-己烯酯等嫩香清香的物质。实验初步验证了超声辅助室温冲泡绿茶的可行性,所得茶汤滋味鲜醇爽口,香气清鲜高长,整体品质优于标准沸水冲泡。超声法特别适用于工业化萃取茶汤,可大大节省能源,降低废气排放。

This study aimed to optimize the conditions for shortening the time required to brew green tea in water at room temperature and simultaneously obtaining quality tea infusion with ultrasound assistance. A comparison with the standard boiling water brewing method was carried out by measuring quality parameters of tea infusions. A tea-to-water ratio of 1：30 （g/mL） and 10 min ultrasound treatment proved optimal. The content of water extracts in tea and the concentrations of tea polyphenolics and caffeine in tea infusion were lower under these conditions than those obtained with the standard boiling water brewing method, whereas total free amino acid levels were achieved by the proposed method. The aroma components from the two brewing methods were substantially identical. However, the tea brewed at room temperature lacked those substances having unpleasant fat odor, such as octanal and （E）-2-octenal but contained increased levels of delicate fragrance substances including alpha-linalool and trans-2-hexenyl caproate. This study provides a preliminary confirmation of the feasibility of ultrasonic-assisted green tea brewing at room temperature, which produces a refreshing and mellow taste and a delicate and long-lasting aroma indicating better overall sensory quality than boiling water brewing. These results indicate that the ultrasound-assisted method is particularly suitable for industrial extraction of tea and can greatly save energy and reduce emissions.