Extraction of active ingredients from green tea (Camellia sinensis):: Extraction efficiency of major catechins and caffeine
Extraction of active ingredients from green tea (Camellia sinensis):: Extraction efficiency of major catechins and caffeine
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DOI：
10.1016/j.foodchem.2005.03.015
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发表时间：
2006-06-01
期刊：
影响因子：
8.8
通讯作者：
Grüner, S
中科院分区：
文献类型：
--
作者：
Perva-Uzunalic, A;Skerget, M;Grüner, S
用不同的水和纯溶剂(丙酮、乙醇、甲醇、乙腈、水)、不同的温度(60、80、95和100℃)和时间(5~240min)，研究了不同的萃取装置对中国绿茶叶中儿茶素和咖啡因的提取效率的影响。分析粗提物中主要儿茶素(EC、EGC、CG、EGCG)、咖啡因、原花青素和黄酮醇(杨梅素、芦荟素、槲皮素)的含量。原料被发现含有191克主要儿茶素/千克物质，36克咖啡因/千克物质和5.2克黄酮醇/千克物质。绿茶提取物中主要儿茶素的含量约为280-580g/kg干提取物，主要儿茶素的萃取率从61%到近100%不等。萃取物中咖啡因的含量为75g/kg，萃取率为62%~76%。平均萃取率为30%，但纯丙酮和乙腈的萃取率约为3%。黄酮醇和原花青素的含量分别为6-20和12-19g/kg。对不同的水提工艺进行了考察，确定了最佳工艺条件：在80℃水浸提20分钟后儿茶素的萃取率最高(97%)，在95℃下浸提10分钟后儿茶素的萃取率最高(90%)。在较高的提取温度和较长的提取时间下，儿茶素有降解现象。采用较低的剂料比，采用多步萃取法，提高了萃取效率。采用CO2高压萃取法提取脱咖啡因绿茶，可选择性地分离出98%的咖啡因，且不会对有价值的儿茶素产生明显影响。(C)2005爱思唯尔有限公司。保留所有权利。
The effect of different extraction set-ups that influence the extraction efficiency of catechins and caffeine from green tea leaves (variety Fanning Belas, China) were studied using different aqueous and pure solvents (acetone, ethanol, methanol, acetonitrile, water), different temperatures (60, 80, 95 and 100 degrees C) and times (5-240 min). Raw extracts were analysed for contents of major catechins (EC, EGC, ECG, EGCG), caffeine, proanthocyanidins and flavonols (myricetin, caempherol, quercetin). Starting material was found to contain 191 g major catechins/kg material, 36 g caffeine/kg material and 5.2 g flavonols/kg material on a dry mass basis. The content of major catechins in green tea extracts varied from approximately 280-580 g/kg dry extract, with extraction efficiencies of major catechins varying from 61% to almost 100%. Content of caffeine in extract was in the range of 75 g/kg, where its extraction efficiency varied from 62% to 76%. Average extraction yield was 30% with exceptions when using pure acetone and acetonitrile, where extraction yield was about 3%. Contents of flavonols and proanthocyanidins were in the ranges 6-20 and 12-19 g/kg, respectively. Different extraction procedures with water were also investigated and optimal conditions determined: maximum achieved extraction efficiency of catechins with water was obtained at 80 degrees C after 20 min (97%) and at 95 degrees C after 10 min of extraction (90%). Degradation of catechins was observed at higher extraction temperatures and with prolonged extraction times. Using a lower ratio of solvent to material, extraction efficiencies were increased by applying a multi-step extraction procedure. Optimal extraction procedure was then performed using decaffeinated green tea leaves, which were obtained by high-pressure extraction with CO2, when 98% of caffeine was selectively isolated without significant impact on valuable catechins. (C) 2005 Elsevier Ltd. All rights reserved.