黑茶中茶多酚及咖啡碱的超临界CO_2流体萃取研究

Extraction of Tea Polyphenols and Caffeine from Black Tea with Supercritical CO_2

以益阳黑茶为原料,采用超临界CO2萃取技术提取黑茶中的茶多酚和咖啡碱,采用正交试验对萃取温度、萃取压力、夹带剂浓度和夹带剂用量等因素进行优化(固定萃取时间为2 h).采用分光光度法测定茶叶中茶多酚和咖啡碱的含量,根据正交试验极差分析结果得出茶多酚的最佳萃取条件:萃取温度50℃,萃取压力20 MPa,夹带剂采用体积分数为70%的乙醇,适宜用量为100 mL/150 g,得率为(0.190±0.004)%.咖啡碱的最佳萃取条件:萃取温度40℃,萃取压力20 MPa,夹带剂采用体积分数为70%的乙醇,适宜用量为300mL/150 g,咖啡碱得率为(0.457±0.036)%.

Supercritical fluid extraction （SFE） was used to extract tea polyphenols and caffeine from black tea. Conditions such as teperature, pressure, entrainer agents concentration and the dosage of entrainer were optimized with orthogonal test （extraction time was 2 hours）. The content of tea polyphenols and caffeine were determined by spectrophotometry. According to the results of orthogonal test, it showed that the optimum conditions were： the extraction temperature 50 ℃, pressure 20 MPa, 70% ethanol solution （in volume ratio） as cosolvent, and the most appropriate amount 100 mL/150 g for tea polyphenols; the extraction temperature 40 ℃, pressure 20 MPa, 70% ethanol solution （in volume ratio） as cosolvent, and the most appropriate amount 300 mL/150 g for coffeine. The extraction rate was （0.190±0.004）% for tea polyphenols and （0.457±0.036）% for caffeine in this extraction condition.