加工贮藏对荷叶茶黄酮类总量及香气和色泽的影响

分别以黄酮含量、黄酮溶出率及香气和色泽确定荷叶最优制茶工艺及荷叶茶的最佳冲泡条件；将制成的荷叶茶分别在贮藏0、6、12 个月时，联用固相微萃取法和气相色谱-质谱法分析其香气成分变化，并用色差仪测定其色泽变化。结果表明，盛开荷叶的黄酮含量最高，以此荷叶为原料，荷叶茶制作最佳加工工艺为：杀青条件640 W、90 s，烘干条件70 ℃，冲泡条件100 ℃、15 min；3 种贮藏期的荷叶茶共鉴定出102 种香气成分，随贮藏时间延长，主要香气物质种类下降，但相对含量升高。苯乙醇是贮藏中、后期荷叶茶的主要呈香物质，贮藏过程中还产生了异戊醇这种异味物质。贮藏最初6 个月内，荷叶茶L*、b*值显著降低，色泽变暗、变蓝，而至12 个月时有所回升，但a*值不断增大，绿度不断降低。

Effect of Processing and Storage on Flavonoids Content,Aroma Components and Color of Lotus Leaf Tea

Based on the content and dissolution rate of flavonoids, aroma and color, this study investigated the optimization of processing and brewing conditions for lotus leaf tea. Lotus leaf tea was stored for 0, 6, and 12 months, and their aroma components were extracted by solid-phase micro-extraction (SPME) and analyzed by gass chromatography-mass spectrometry (GC-MS). Color changes of lotus leaf tea were also measured using a color difference meter. The highest content of flavonoids was found in the full-bloom lotus leaves. The optimized conditions for processing lotus leaf tea were determined as fixation by microwave irradiation at 640 W for 90 s and drying at 70 ℃; and the optimized brewing conditions were 100 ℃ for 15 min. A total of 102 aroma components were identified in lotus leaf tea after three storage periods. As the storage time prolonged, the number of main aroma components decreased, but their relative contents increased. Benzyl alcohol was the main aroma component in lotus leaf tea stored for 6 and 12 months. Moreover, isoamylol responsible for the unpleasant odor was generated during storage. During the first 6 months of storage, the L* and b* values of lotus leaf tea remarkably decreased, as the color became dimmer and was changed to blue, and the L* and b* values increased slightly at the last stage of storage. While the a* value increased continuously in the whole storage period, the greenness decreased continuously.