日晒是晒青毛茶品质形成的关键。该研究比较了日光干燥、晒青棚干燥和晒青棚内加紫外灯干燥3种晒干方式对晒青绿茶中脂肪酸、挥发性化合物和感官品质的影响。在晒青绿茶中共检测出7种脂肪酸,不饱和脂肪酸占比最高约为60%,其中亚麻酸和亚油酸具有较高含量。所有处理中,紫外强度最高的日光干燥处理使不饱和脂肪酸的降解程度最大,为35.73%,且差异显著(P<0.05)。晒青绿茶中共检测出84种挥发性化合物,其中醛类和醇类是主要的化合物类别,醛类物质含量所占比例最高,约为23%~42%。与揉捻叶相比,晒青棚干燥,晒青棚加紫外干燥,日光干燥处理后醛类化合物总含量分别上升了50%,112%和205%。经感官评价,日光干燥后的晒青绿茶风味品质最佳,得分均高于其余2组,更受消费者所喜爱。综上,在紫外强度较高的处理中,其变化都呈现出较好的态势,该研究结果可为人工模拟晒青绿茶的日光干燥,完善现有晒青技术提供理论依据。
Sun drying is the key technique for the quality formation of sun-dried green tea. In this study, the effect of three sun drying treatments, namely sun drying, sun drying shed and ultraviolet lamp irradiation under sun drying shed on fatty acids, volatile compounds, and sensory quality were compared. Results showed that there were totally seven fatty acids were detected, and unsaturated fatty acids account for up to about 60%. Among which, linolenic acid, and linoleic acid had higher contents. Moreover, the sun drying with the highest UV intensity led to the significant (P<0.05) degradation of unsaturated fatty acids which was 35.73%. A total of 84 volatiles were identified, among which aldehydes and alcohols were the major chemical classes. And the content of aldehydes was the highest which reached 23%-42%. The treatment of sun drying shed, ultraviolet lamp irradiation under sun drying shed and sun drying increased the contents of volatile compounds such as aldehydes by 50%, 112% and 205%, respectively, compared with rolled leaves. In summary, in the treatment with higher UV intensity, the changes showed a good trend. This study provides a theoretical basis for artificially simulating the drying of sun-dried green tea and which help to improve the existing sun-drying shed technology.
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