研究黄茶闷黄过程中主要化学成分与色差在不同温度、不同含水量条件下随闷黄时间的变化规律，确定引起黄茶黄变的关键化学成分为叶绿素a、EGCG和ECG，并建立了叶绿素a、EGCG和ECG随闷黄时间、闷黄温度之间的动力学模型，以预测黄茶闷黄过程中的黄变程度。结果表明：叶绿素a、EGCG及ECG与零级动力学方程的拟合程度较优，基于各模型的预测值与实际实验值之间的相对误差小于5%，说明该模型有效，并通过预测的模型计算出了各条件下的反应速率常数K，发现随着温度和含水量的增加，叶绿素a、EGCG和ECG的反应速率常数K逐渐增大，采用Arrhenius方程对反应速率常数k和温度T进行非线性拟合，得到了叶绿素a、EGCG和ECG的活化能Ea与频率因子A，判断出相同条件下叶绿素a反应最易进行，其次是ECG、EGCG。

Changes in the color difference and main chemical composition of yellow tea, along with piling time, were studied at different temperatures and different water content. The key chemical components causing the yellowing of yellow tea are chlorophyll a, epigallocatechin gallate (EGCG), and epicatechin gallate (ECG), and kinetic models for the relationship of chlorophyll a, EGCG, and ECG with piling time and temperature were established, so as to predict the degree of yellowing during the piling process. The results showed that a zero-order kinetic equation could provide a good fit for chlorophyll a, EGCG, and ECG. The relative error of the model predicted value and actual value was less than 5%, indicating that the model was effective. The reaction rate constant K (reaction rate) values for the prediction model were calculated under various conditions, and the results indicated that with increasing temperature and moisture content, the K values of chlorophyll a, EGCG, ECG increased gradually. Nonlinear fitting of reaction rate constant and temperature were carried out using the Arrhenius equation, and the Ea (activation energy) and A (frequency factor) of chlorophyll a, EGCG, and ECG were obtained. Under the same conditions, the reaction of chlorophyll a was most likely to occur, followed by those of ECG and EGCG.

重庆市科委资助（cstc2013jcsfC80002）