| 【Objective】The effects of baking on the color changes of summer-autumn green teas were studied to lay a foundation for the optimal application of baking technology in quality improvement of summerautumn green teas.【Method】The baking processes of summer-autumn green tea were simulated to compare and analyze the dynamic changes of sensory quality, color difference indexes and the main physicochemical components affecting the color changes of tea leaves.【Result】The color of summer-autumn green tea changed from dark green, yellow green, red yellow to red brown during the baking process. The color difference indexes L*, a* and b* showed an increasing trend with the prolonging of baking time at the same baking temperature. During the baking process, the thermal degradation of chlorophyll (a and b) presented as a first-order kinetic reaction.With the increase of temperature, the reaction rate constant k of chlorophyll (a and b) was increased and the half-life (t1/2) was shortened, and the degradation rate of chlorophyll b was higher than that of chlorophyll a. The total contents of tea polyphenols, catechins and free amino acids in the baking process showed a gradually decreasing trend.【Conclusion】The color difference of tea leaves changed slightly in low temperature baking at 80 ℃ , the degradation rate of chlorophyll was slow, the total contents of tea polyphenolics, catechins and free amino acids had lowest decrease and tea color quality could be maintained to the best level. |
