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Effect of different drying methods on the sensory quality and chemical components of black tea

Qu, Fengfeng, Zhu, Xiaojing, Ai, Zeyi, Ai, Yujie, Qiu, Fangfang, Ni, Dejiang
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2019 v.99 pp. 112-118
amino acids, black tea, color, flavanols, gas chromatography-mass spectrometry, halogens, lamps, microwave drying, odors, sensory evaluation, sugars, taste, theaflavins, volatile compounds
This study investigated the effects of conventional hot-air drying, microwave drying, far-infrared drying, halogen lamp drying and halogen lamp-microwave combination drying on sensory and chemical quality of black tea. Sensory evaluation revealed that the black tea dried with halogen lamp-microwave and microwave got more uniform black color, fresher taste and higher sweet aroma. Total quality score was in the order: halogen lamp-microwave dried tea (89.3) > microwave dried tea (88.2) > halogen lamp dried tea (86.4) > far-infrared dried tea (85.2) > hot-air dried tea (83.1). The highest contents of polyphenols, catechins and theaflavins were found when black tea dried with microwave. Far-infrared drying and hot-air drying could remarkably increase the contents of amino acids and soluble sugars. The volatiles of black tea were identified with gas chromatography-mass spectrometry. Microwave dried black tea got the maximum contents of volatile compounds, followed by halogen lamp-microwave dried tea, far-infrared dried tea, halogen lamp dried tea and hot-air dried tea. Overall, microwave drying and halogen lamp-microwave drying could ameliorate the drying process of black tea.