青砖茶加工过程品质成分变化研究

目的研究青砖茶加工过程中各化学品质成分含量的变化,为青砖茶风味品质形成提供理论依据。方法以青砖茶发酵前、发酵后及成品为材料,比较分析样品水分、水浸出物、游离氨基酸、咖啡碱、茶多酚、儿茶素组分、茶黄素组分、粗纤维、黄酮、可溶性糖、可溶性果胶等含量变化。结果青砖茶加工过程中,水分含量基本不变,控制在9%左右;纤维素含量呈现上升趋势,成品达到(21.29±0.78)%;水浸出物、可溶性总糖、儿茶素、茶黄素-3'-没食子酸酯、茶黄素总量呈现下降趋势;黄酮含量总体较为稳定,为1.40%~1.83%;茶黄素-3,3'-双没食子酸酯基本稳定在1 mg/g左右;咖啡碱含量发酵后显著低于发酵前;氨基酸、茶多酚、表儿茶素、表儿茶素没食子酸酯、表没食子儿茶素、表没食子儿茶素没食子酸酯、儿茶素总量、茶黄素、茶黄素-3'-没食子酸酯、水溶性果胶均呈现下降后上升,但成品含量低于发酵前原料含量的趋势。结论青砖茶加工过程中不同生化成分变化趋势存在差异,成品与原料存在较大差异,具有粗涩味作用的成分含量降低,各成分间含量更加协调,为青砖茶醇和风味品质形成奠定基础。

Changes of components in Chin-brick tea during processing

Objective To analyze the changes of chemical substance content in Chin-brick tea during processing, in order to provide the theoretical basis for the formation of Chin-brick tea flavor. Methods Samples of Chin-brick tea of before and after fermenting, and the final products were analyzed for main chemical components, including water content, water extract, amino acids, caffeine, polyphenols, catechins, theaflavins, crude fiber, flavonoid, soluble sugar and soluble pectin. Results During processing of Chin-brick tea, the water content remained almost the same, which was up to 9%. With the final content of (21.29±0.78)%, cellulose showed an upward trend. However, the content of water extract, soluble sugar, catechin, theaflavins-3''-gallate and total amount of theaflavins showed downward trends during the tea processing. Overall, the content of flavonoid was in stability, between 1.40% and 1.83%, and theaflavin-3,3''-gallate was stable at about 1 mg/g. The content of caffeine after fermentation was significantly lower than those before fermentation. The content of amino acids, tea polyphenols, epicatechin, epicatechin gallate, epigallocatechin gallate, total amount of catechin, theaflavins, theaflavins-3''-gallate and water-soluble pectin showed a rise after the decline, with the finished product content lower than those before fermentation. Conclusion The variation trends of different biochemical components during processing of Chin-brick tea are different. There is a big difference between the final product and the materials before or during the fermentation, with the lower content of some coarse and astringency tastes, more coordinated among each component, which lays a foundation for the formation of mellow flavor quality in Chin-brick tea.