超声-搅拌辅助冷泡绿茶的功能成分与感官评价

Functional Components and Sensory Quality of Extracted Green Tea Prepared by Ultrasound-stirring-assisted Cold Brewing

摘要:

【目的】制备兼具优良感官和功能活性的冷萃绿茶。【方法】对比超声-搅拌辅助冷泡、常规热泡、常规冷泡3种工艺所得绿茶的理化特性和风味品质。【结果】超声-搅拌辅助冷泡可促进多酚及游离氨基酸（尤其是茶氨酸）的溶出，茶汤酚氨比为1.33，与常规冷泡茶相近；另外，该工艺可显著提升冷泡绿茶的抗氧化能力，其ABTS ^＋、DPPH自由基清除率分别为（72.07±3.04）%、（49.54±1.59）%。挥发性成分分析结果表明，超声-搅拌辅助冷泡工艺提高了茶汤中醛类、酮类、酯类物质的溶出，茶汤香气浓郁。基于OPLS-DA模型分析发现，3种冲泡方式茶汤的挥发性成分具有显著差异，共筛选得到35种VIP>1的差异物质。相较于常规热泡茶，超声-搅拌辅助冷泡能更好地保留绿茶原有的清新香气；相较于常规冷泡茶，其香气物质更加丰富。OAV分析发现，超声-搅拌辅助冷泡茶保留了常规冷泡茶的特征香气属性，提升了1-辛烯-3-醇、壬醛、正辛醇的香气感知，OAV值分别为5.51、3.76、1.52。感官评价结果表明，超声-搅拌辅助冷泡茶具有青草香、花香、果香、焙烤香等绿茶香气特征，可接受度较高。【结论】超声-搅拌辅助冷泡工艺适用于高品质冷萃绿茶的加工，可为冷萃茶的品质提升提供工艺参考。

Abstract:

[Objective] This study aimed to prepare cold extracted green tea with good sensory quality and health functions. [Method] The physicochemical and flavor characteristics of cold extracted green tea prepared through ultrasound-stirring-assisted cold brewing were compared with those of green tea prepared through conventional hot brewing and conventional cold brewing. [Result] Ultrasound-stirring-assisted cold brewing promoted the dissolution of polyphenols and free amino acids (especially theanine), and the tea infusion had a phenol-ammonia ratio (1.33) comparable to that of conventional cold brewed tea. In addition, this process significantly enhanced the antioxidant capacity of cold extracted green tea, which showed the ABTS ⁺ and DPPH radical scavenging rate of (72.07±3.04)% and (49.54±1.59)%, respectively. Determination of volatile components revealed that the ultrasound-stirring-assisted cold brewing process improved the dissolution of aldehydes, ketones, and esters in the tea infusion, which showed a strong aroma. The OPLS-DA model analysis showed significant differences in volatile components between tea infusions brewed with the three methods, and 35 differential compounds with VIP>1 were screened out. Ultrasound-stirring-assisted cold brewing better retained the original freshness and aroma of green tea than conventional hot brewing and endowed the tea infusion with richer aroma compounds than conventional cold brewing. The OAV analysis showed that ultrasound-stirring-assisted cold brewing retained the characteristic aroma attributes of the tea infusion prepared through conventional cold brewing and enhanced the aroma perception of 1-octen-3-ol, nonanal, and 1-octanol, which showed the OAV values of 5.51, 3.76, and 1.52, respectively. The results of sensory evaluation showed that the tea infusion prepared through ultrasound-stirring-assisted cold brewing had the green tea aroma characteristics such as grassy, floral, fruity, and baking aromas, with a degree of acceptability. [Conclusion] Ultrasonic-stirring-assisted cold brewing has the potential to prepare high-quality cold extracted green tea, which can provide process guidance for the quality improvement of cold extracted tea.