低温真空干燥气流循环方式对铁观音品质的影响

Effect of Air Circulation in Low-temperature Vacuum Drying on Quality of Tieguanyin Tea

为提高茶叶干燥品质,节约能耗,将低温真空干燥新技术应用于乌龙茶干燥,开展低温真空干燥的不同气流循环方式对铁观音生化及品质的影响研究。结果表明,气流外循环(A2)处理的毛茶水浸出物(37.11%)、茶多酚(25.22%)、氨基酸(1.83%)、黄酮类(6.05 mg·g-1)高于内循环(A1)和对照组(CK);三泡茶汤间茶多酚、氨基酸、咖啡碱浸出率波动幅度均最小,浸出较为均匀;干茶色泽砂绿润,茶汤色泽偏浅黄绿;毛茶感官品质得分:A2(89.27±0.21)>A1(86.27±0.26)>CK(85.31±0.18)。综上,低温真空干燥气流外循环(A2)方式对于铁观音品质综合效果最佳。

To improve the oolong tea quality and conserve energy in processing,the low-temperature vacuum dehydration was supplemented with forced air circulation for evaluation.Various means of air circulation were implemented to study their effect on the biochemistry and quality of the dried Tieguanyin tea.It was found that the external air circulation（A2）produced higher amounts of water extracts（37.11%）,tea polyphenols（25.22%）,amino acids（1.83%）and flavonoids（6.05mg·g-1）in the tea than the close-loop air circulation（A1）or without a forced air circulation（CK）.The differences on the contents of polyphenols,amino acids and caffeine were not significant among the samples steeped for 3times.The dried tea leaves were green,and the brewed tea light yellowish green in color.Sensory evaluation on the tea samples made by the various methods gave A2 the highest score at 89.27±0.21,followed by A1 at 86.27±0.26,and CK the lowest at 85.31±0.18.It appeared that,when the low-temperature vacuum drying was carried out with an external air circulation,the quality of Tieguanyin tea could be improved.