乌龙茶水提物的膜分离制备及其体外抗氧化活性评价

Preparation of Oolong Tea Water Extract by Membrane Separation and Evaluation of Antioxidant Activity In Vitro

摘要:

为探究乌龙茶水提液的不同膜分离工艺对产品品质、生化成分及体外抗氧化活性的影响，采用陶瓷膜(500 nm)和超滤膜(20、10、5、3.5 kD)对乌龙茶水提液进行分离，经喷雾干燥制得茶粉。通过感官品质、物理性质等方面评价不同膜分离工艺所制备的茶粉品质，并对茶粉的主要生化成分进行分析比较。同时，通过DPPH自由基清除力、FRAP氧化还原力、羟基自由基清除力、抗超氧阴离子活力方法评价茶粉的体外抗氧化活性。结果表明，陶瓷膜透过液的感官品质综合得分最高，体外抗氧化活性亦最高。500 nm陶瓷膜可有效分离与富集茶多酚(TPs)、游离氨基酸(FAAs)、咖啡碱(CAF)、可溶性糖(SPS)等物质，还可达到除杂效果，经陶瓷膜分离后的乌龙茶水提液再经超滤膜分离，对TPs、CAF、SPS、儿茶素组分无分离与富集效果。截留分子量小于10 kDa的超滤膜可有效分离与富集游离氨基酸。500 nm陶瓷膜截留液的SPS含量最高，但综合感官品质最差，抗氧化活性最低。基于品质、功效、节能3大要素考虑，500 nm陶瓷膜透过液制备的茶粉综合品质最优。

Abstract:

In order to investigate the effects of different membrane separation processes on product quality, biochemical components and antioxidant activity in vitro, the water extract of Oolong tea was separated by ceramic membrane (500 nm) and ultrafiltration membrane (20, 10, 5, 3.5 kD), and tea powder was prepared by spray drying. The quality of tea powder prepared by different membrane separation processes was evaluated through sensory quality and physical properties, and the main biochemical components of tea powder were analyzed and compared. Meanwhile, the antioxidant activity of tea powder in vitro was evaluated by DPPH radical scavenging capacity, the ferric ion reducing antioxidant power (FRAP), hydroxyl radical scavenging capacity and anti- superoxide anion activity. The results showed that the sensory quality and antioxidant activity of ceramic membrane were the highest. The 500 nm ceramic membrane can effectively separate and enrich tea polyphenols (TPs), free amino acids (FAAs), caffeine (CAF), soluble sugar (SPS) and other substances, but also achieve the effect of impurity removal. The water extract of Oolong tea separated by ceramic membrane and then separated by ultrafiltration membrane, TPs, CAF, SPS, catechin components have no separation and enrichment effect. Ultra- filtration membranes with molecular weight less than 10 kDa can effectively separate and enrich free amino acids. The 500 nm ceramic membrane interception solution had the highest SPS content, but the worst sensory quality and the lowest antioxidant activity. Therefore, considering the three factors of quality, efficiency and energy saving, the comprehensive quality of tea powder prepared by 500 nm ceramic membrane through liquid is the best.