白茶压饼过程理化指标与感官品质的动态变化

为了解白茶压饼过程各工艺关键点对白茶品质形成影响及作用机制,将白茶压饼过程分为瞬时蒸汽高温高湿ZQ、模拟压饼时湿闷状态SM、压饼力作用YS、压饼力作用后长时烘干YB作用,探讨白茶压饼过程各关键点ZQ、SM、YS、YB处理中白茶制品生化成分和感官品质的动态变化。结果表明,ZQ、SM、YS、YB处理对白茶外形由松散变为紧实作用效果显著,容重比原始样增加1.0~1.5倍;ZQ处理是影响色泽的重要工序,降低氨基酸含量,散发青气;SM处理促进蛋白质水解,积累氨基酸,大幅度提高茶红素含量;YS引起茶多酚下降,茶汤浓度增加,滋味转鲜爽;YB处理茶多酚大幅度提高,香气由青、杂转化为陈、药香味,滋味变浓醇,是白茶饼特征香气,滋味品质形成的关键工序。

Changes on Physical,Chemical and Sensory Properties of Compressed White Tea Cakes During Processing

To decipher the quality in relation to processing of compressed white tea cakes,the physical and chemical changes of the tea leaves at key stages in varied processes were monitored.Four treatments,including steaming (ZQ),moisturizing (SM),pressing (YS) and prolonged drying after compressing (YB),in the making of the product were applied for evaluation.All treatments exerted significant effects on the compactness of the cakes with a 100％-150％ increase on the bulk density.Among the treatments,ZQ also significantly affected the leaf color,amino acid content and green note reduction;SM stimulated protein hydrolysis as well as amino acid and thearubigins accumulations;YS lowered the polyphenol content,and increased the concentration and freshness of the brewed tea;and,YB encouraged formation of the characteristic aroma and taste of the white tea cakes with increased water extracts and polyphenols as well as heightened conversion of green/earthy to fragrant/elegant note for the brewed tea.