茶叶中咖啡因提取方法的比较

Comparison of methods of extraction caffeine from tea

茶叶是人们生活中的重要饮品,我国茶叶的产销量居世界前列。如何更好地高效利用我国每年滞销的5万多吨中低档茶叶,是广大茶叶利用研究工作者和茶农们的共同心声。而茶叶中具有许多生物生理活性物质,其中咖啡因就是当中含量较高的一种。我们以绿茶为原料,通过L16(45)正交试验考察了微波辅助提取法从茶叶中提取咖啡因的影响情况,并以传统的Soxhlet提取法为对照。正交试验表明,从茶叶中提取咖啡因的最佳提取方案为:微波功率0.2kW、提取剂80%(v/v)乙醇、料液比为1:16(m/V)、浸提时间9min(间隙式提取)、温度83±5℃、连续提取3次,使用自制复合中和沉淀剂,咖啡因提取率平均达到217.5mg/10g茶样,较Soxhlet法提取6h的144.8mg/10g茶样高50.2%,最高可达221.8mg/10g茶样,比Soxhlet法的148.8mg/10g茶样高49.1%。而且微波法所得咖啡因的纯度、外观和稳定性等质量指标明显优于Soxhlet法。这为传统的茶叶提取咖啡因工艺的升级改造提供了实验依据。

Tea is very important for Chinese people.The tea production and sales in China is in the leading place of the world.In this experiment,green tea was used as raw material,caffeine was extracted by microwave-assisted extraction method.The impact factors was studied by L16（45）orthogonal experiment and used the traditional Soxhlet extraction as the control.The experiment results showed that the best extraction conditions were as follows：microwave power 0.2kW,extraction agent 80%（v/v）ethanol,solid-liquid ratio of 1：16（m/V）,extraction time of microwave irradiation 9 min（gap-type extract）,caffeine yield was 217.5mg/10g,50.2%higher than Soxhlet extraction which caffeine yield was 144.8mg/10g after 6 hours extration.The highest yield was 221.8mg/10g which was 49.1% higher than the highest Soxhlet extraction＇s of 148.8mg/10g.The quality indicators of caffeine obtained by microwave method such as purity,appearance and stability etc.,were remarkable superior to Soxhlet method’s.This provides the basic information for further studies in the future.