不同干燥方式对黑茶品质的影响

目的 黑茶传统自然干燥工艺受天气、卫生、效率等因素局限,本文探讨黑茶采用现代机械干燥替代传统干燥的可行性。方法 以云南晒青毛茶渥堆叶为原料,采用不同干燥工艺(热风烘干、远红外干燥、炒干、微波干燥、光波干燥、微波光波混合干燥、晒干、晾干)制成黑茶。分析其感官品质、主要品质成分变化。结果 不同干燥方式加工的黑茶干茶色泽、汤色、叶底基本一致,香气和滋味相差较大。其中热风烘干的黑茶陈香突出,综合品质最高,其游离氨基酸含量较高。远红外干燥的黑茶滋味略带苦味,陈香较弱,其咖啡碱、儿茶素总量较低,滋味的浓度、协调度均不足。炒干的黑茶条索更紧结,香气带陈香较清新,滋味醇和,其可溶性糖、含量相对较高。微波干燥的黑茶滋味甜醇,稍带闷气,其可溶性糖、茶红素含量较高。光波干燥的黑茶茶滋味有甜醇风味及特殊香气,其游离氨基酸含量相对较高。微光波混合干燥的茶有甜醇味,香气略陈,其游离氨基酸、可溶性糖和咖啡碱的含量均介于微波与光波干燥之间,茶多酚的含量高于其他干燥方式。晒干的茶滋味涩,香气为日晒气,其游离氨基酸、可溶性糖含量较低,茶褐素含量高,儿茶素含量较高。晾干的茶滋味有涩味,口感低淡,其游离氨基酸、可溶性糖含量较低,茶褐素含量相对较高。 结论 结合感官品质和理化分析,黑茶加工干燥环节,热风烘干、炒干、微波干燥、光波干燥、微光波混合干燥等现代机械干燥方式可以取代传统的晒干和晾干方式。

Effects of different drying methods on quality of dark tea

Objective To explore the feasibility of using modern mechanical drying instead of traditional drying in dark tea processing. Methods Dark tea was made from the leaves of Yunnan sun-dried green tea after pile-fermentation by 8 kinds of different of drying methods, including hot air drying, far-infrared drying, stir-frying, microwave drying, light wave drying, microwave light wave mixed drying, sun drying and air drying, the sensory quality and main quality components changes were analyzed. Results The appearance of dry tea and tea infusions and brewed leaves of dried dark tea processed by different drying methods were basically the same, but the aroma and taste were different greatly. Among them, the hot air drying dark tea had outstanding aging aroma, the highest comprehensive quality and higher free amino acid content; far-infrared dry dark tea had a slightly bitter taste and weak aging aroma, the total content of caffeine and catechin was low; and the taste concentration and coordination degree were insufficient; stir-dried dark tea had a tighter string, a fresher aroma, a mellow taste and a relatively high soluble sugar content; microwave dried dark tea tasted sweet and mellow, slightly stuffy, with higher soluble sugar and theabrownin content; light wave dried dark tea had sweet and mellow flavor and special aroma, and its free amino acid content was relatively high; microwave-light wave mixed drying dark tea had sweet and mellow taste and slightly old aroma, the content of free amino acids, soluble sugar and caffeine were between microwave and light wave drying dark tea, and the content of tea polyphenols was higher than the dark tea with other drying methods; the sun-dried dark tea tasted astringent and had a sun-dried aroma, while the air-dried dark tea tasted astringent and low in taste, the content of free amino acids and soluble sugar in dark tea under the 2 kinds of drying methods were relatively low, and the content of theabrownin was relatively high. Conclusion Combining sensory quality and physicochemical analysis, modern mechanical drying methods such as hot air drying, stir-frying, microwave drying, light wave drying and microwave light wave mixed drying can replace traditional sun drying and air drying methods.