Impact of key primary processing technologies on the quality of granular green tea(颗粒形绿茶初制关键技术对品质的影响)

Granular green tea is a significant category of famous high-quality green tea in Zhejiang Province. In this study, we conducted comparative experiments on key technical parameters, including moisture resurgence, second fixation and stir-frying techniques, during the primary processing of granular green tea and systematically analyzed their effects on sensory quality and chemical composition. The results indicated that appropriately controlling the rehumidification time (1.5 h), reducing the moisture content of the second fixed leaves (40%), decreasing the amount of tea leaves per frying pan (4 kg/pan), and selecting a frying pan with better air permeability (60-type) effectively enhanced the dry tea appearance and the emerald color of the tea liquor and improved the freshness of the aroma and taste. Moderate rehumidification and a lower moisture content in the second fixed leaves increased the content of catechins and some key umami amino acids, whereas a lower loading amount of tea leaves per frying pan increased the total amino acid content; a higher moisture content in the second fixed leaves increased the water extract content. Higher-quality samples with superior aroma and freshness had higher levels of floral compounds such as linalool, geraniol, and α-terpineol. Conversely, a longer rehumidification time, greater moisture content in the second fixed leaves, more tea leaves per frying pan, and lower air permeability of the stir-frying machine led to higher temperatures and moisture and increased the relative content of compounds such as n-hexadecanoic acid, heptanoic acid, and 6, 10, 14-trimethyl-2-pentadecanone in the aroma profile. In conclusion, this study identifies an optimal processing combination for improving the overall quality of granular green tea and provides a theoretical basis for refining its processing technology.(颗粒形绿茶是浙江省名优绿茶的重要品类。本研究针对颗粒形绿茶初制中回潮、二青、炒制等工序的关键技术参数开展对比试验，系统分析不同技术参数对颗粒形绿茶感官品质及化学组分的影响。结果表明，适当控制回潮时间（1.5 h）、降低二青叶含水率（40%）、适当减少炒制投叶量（4 kg/小锅）及选用透气性能较好的炒锅（60型），能够提升颗粒形绿茶外形及茶汤的翠绿色泽，并提高香气滋味的鲜爽性。适度回潮和较低的二青叶含水率有助于提升儿茶素含量及部分对鲜味具有重要贡献的氨基酸含量；较低的炒制投叶量可提升氨基酸总量；而较高的二青叶含水率则有利于提升水浸出物含量。在香气鲜爽性高、品质较优的样品中，芳樟醇、香叶醇、α-松油醇等具有花香特征的化合物的相对含量较高；而长时间回潮、较高的二青叶含水率、较高的炒制投叶量及较低透气性的锅型所引起的较高温度及含水率，则会促进正十六烷酸、庚酸、6，10，14-三甲基-2-十五烷酮等香气组分的积累。本研究明确了提升颗粒形绿茶综合品质的适宜工艺组合，为优化其加工技术提供了理论依据。)