Tea Research Laboratory, Agricultural and Food Engineering Department, Indian Institute of Technology Kharagpur, Kharagpur, 721 302 India.
J Food Sci Technol. 2015 Apr;52(4):2387-93. doi: 10.1007/s13197-013-1230-5. Epub 2013 Dec 13.
In black tea manufacturing, one of the most important steps is fermentation which influences the quality of tea. The macerated tea leaves were fermented at various temperatures (20, 25, 30, 35 °C) for different duration. Changes in polyphenoloxidase and peroxidase activities, depletion patterns of individual catechins, differences in individual theaflavin levels and formation of thearubigins were measured in leaves during fermentation. Higher stability of polyphenoloxidase and peroxidase enzymes was observed at lower temperature (20 °C), and increase in temperature, led to enzyme instability. The rate of degradation of all the catechins was found to be fastest at 35 °C and slowest at 20 °C. The formation and depletion of individual theaflavins varied with temperature and fermentation duration. The time required for the formation of maximum total theaflavins (TF) was highest at lower temperature and this time duration also varied for different theaflavins formation. Maximum amount of thearubigins (TR) content and liquor colour development was observed at 35 °C, and decrease in temperature reduced thearubigins accumulation. However, maximum brightness as well as TF/TR ratio was obtained at 20 °C, which suggests that fermentation at lower temperature is suitable for manufacturing quality black tea.
在红茶制作中，发酵是最重要的步骤之一，它会影响茶叶的质量。将揉捻后的茶叶在不同温度（20、25、30、35°C）下发酵不同的时间。在发酵过程中，测量了茶叶中多酚氧化酶和过氧化物酶活性的变化、儿茶素单体的消耗模式、茶黄素单体水平的差异以及茶红素的形成。在较低的温度（20°C）下，多酚氧化酶和过氧化物酶的稳定性更高，而温度的升高会导致酶的不稳定性。所有儿茶素的降解速度在 35°C 时最快，在 20°C 时最慢。不同温度和发酵时间会影响茶黄素单体的形成和消耗。形成最大总量茶黄素（TF）所需的时间在较低温度下最高，不同茶黄素单体形成所需的时间也不同。在 35°C 时观察到最大量的茶红素（TR）含量和汤色发展，而温度降低会减少茶红素的积累。然而，在 20°C 时获得了最大的亮度以及 TF/TR 比值，这表明低温发酵适合制造优质红茶。
