超声波辅助提取与电渗析脱盐耦合技术对绿茶茶汤理化性质的影响

本文对比不同功率超声辅助热水提取与传统热水提取的绿茶茶汤理化性质差异，并对其进行电渗析处理，探究电渗析对绿茶茶汤的理化性质及冷却后浊度及沉淀率的影响。结果表明，超声辅助热水提取的绿茶茶汤中可溶性固形物、茶多酚含量、咖啡碱含量均高于传统热水提取，且随超声功率增大先升高后降低，超声功率增加至390 W时，绿茶茶汤中茶多酚及咖啡碱含量达最大值，分别为5903.14、1091.87 mg/kg。电渗析处理能显著降低绿茶茶汤中金属离子含量及电导率，热水提取、130 W超声提取及520 W超声提取的茶汤中钾的脱除率分别为67.46%、80.20%、89.59%，锰的脱除率分别为64.92%、77.35%、88.56%；电渗析处理可显著降低绿茶茶汤的浊度，并对茶汤的“冷后浑”具有抑制效果，且对超声辅助提取的茶汤“冷后浑”的抑制效果较热水提取效果更好。

Effect of Ultrasonic-assisted Extraction Coupled with Electrodialytic Desalination on the Physicochemical Property of Green Tea Infusions

In this article, the impact of different extraction methods (including ultrasonic-assisted hot water extraction and conventional hot water extraction) on the physicochemical property of green tea infusions was investigated. Moreover, the influence of the electroosmosis process on the turbidity and precipitation rate of green tea infusions before and after cooling was also evaluated. The results implied that the contents of soluble-solid, catechin and caffeine in green tea infusions extracted by ultrasonic-assisted hot water method were higher than those extracted by conventional hot water extraction alone. With increasing of the ultrasonic power, the levels of catechin and caffeine in green tea infusions firstly increased and subsequently decreased, and reached the maximum values (5903.14 and 1091.87 mg/kg, respectively) when the ultrasonic power elevated to 390 W. The results also indicated that the level of metal ions and electrical conductivity were significantly decreased after electrodialysis treatment. After electrodialysis treatment of green tea infusions extracted by hot water extraction alone and ultrasound-assisted hot water extraction at power levels of 130 W and 390 W, the removal rates of potassium were 67.46%, 80.20% and 89.59% respectively, the removal rates of manganese were 64.92%, 77.35% and 88.56% respectively. The turbidity of green tea infusions significantly deceased and the formation of tea cream after cooling was obviously inhibited after electroosmosis treatment.