茶叶有效成分复合分离提取技术研究

    Comprehensive Extraction Technologies of Active Constituents of Tea

    • 摘要: 以中、低档绿茶为原料,研究了茶多酚、咖啡碱和茶多糖的复合提取技术,探讨了微波对绿茶茶多酚类物质浸出特性的影响,建立了从同一茶叶原料中同时获得茶多酚、茶多糖、咖啡碱3种产品的工艺。研究结果表明:1)以水为介质,微波处理绿茶有利于茶叶有效成分的浸出,平均粒径0.246mm的绿茶用料液比(W/V)1∶20,时间3min,微波浸提2次,再50℃水浴浸提10min,1次,茶多酚浸提率达90.73%,高于乙醇水浸提。2)Al3+沉淀茶多酚的最佳pH范围为5.3~5.7;确定茶多酚——铝盐的最佳转溶条件为:茶多酚——铝盐沉淀用pH1.5的酸溶液,以料酸比1∶2(V/V)于60℃水浴中转溶15min,1次,茶多酚的转溶率达79.09%。3)萃取法结合升华法制备咖啡碱,较直接升华法得率高;确定咖啡碱最佳萃取条件为:供试液中NaCl浓度0.2%,二倍量的乙酸乙酯萃取3次,咖啡碱萃取率达95.14%。4)以水为介质,茶末经微波联合水浴浸提,溶剂法和沉淀法分离,能制备得率为11.8%的茶多酚、1.5%的茶多糖和1.2%的咖啡碱,效果明显优于单一溶剂法和沉淀法

       

      Abstract: Using mid-grade and low grade green tea as raw material, the comprehensive technology of extracting tea-polyphenols, tea-polysaccharide and caffeine was studied. The effect of microwave treatment on tea-polyphenol leaching characteristics was probed and the technology of extracting tea-polyphenols, tea-polysaccharides, and caffeine from the same tea material was developed. The result demonstrated that microwave treatment could improve leaching active constituents of green tea. Using purified water as the solvent, being leached 2 times by microwave (material-water ratio 1∶20, time: 3 min), the green tea with an average size of 0.246 mm was leached by purified water (50℃) once in 10 minutes. The result showed that the leaching rate of tea polyphenols was 90.73%, which was higher than that of being leached by the mixture of ethyl alcohol and water. Using Al3+ to sediment tea-polyphenols, it was also revealed that the best range of pH was from 5.3 to 5.7. Using acid solution with pH1.5 to dissolve TP-Al 3+ (ratio between experimental solution and acid solution was 1∶2), the mixture of acid solution and TP-Al3+ was soaked in the water (50℃) for 15 minutes. The result showed that it was the best dissolved condition and the dissolved rate was 79.09%. The experiment combined the extractive method with the sublimational method to prepare caffeine, and the result showed that the production of caffeine was higher than that of direct sublimational preparation. It was also revealed that the experimental solution among which the concentration of NaCl was 0.2% was extracted 3 times by acetic ether whose volume was two times the experimental solution, the extraction rate was 95.14%. Using purified water as the solvent, leached by microwave treatment and water, separated by solvent extraction and sedimental extraction, tea powder could prepare tea-polyphenols about 11.8%, tea-polysaccharide about 1.5% and caffeine about 1.2%. This is remarkably superior to single solvent and sedimental extraction.

       

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