Relationship between color change and quality of Pu-erh Tea during fermentation

The relationship between the chromatism and the quality of Pu-erh Tea in different fermentation stages were investigated in this paper. Sensory quality, quantitative analysis of tea infusion and the content change in tea pigments in different fermentation stages under conditions of constant temperature and humidity or constant temperature and non-constant humidity were determined in Saccharomyces cerevisiae inoculated or noninoculated Pu-erh Teas. It was found that the brightness index L and the brightness index difference ?L had a positive proportional relationship with the sensory score of tea infusion color. Chromaticity index (a, b) and chromaticity value (?a, ?b) were significantly positively correlated with sensory value, taste value and total quality value of tea infusion. The values of ?L and ?b gradually decreased during different fermentation stages, but the value of ?a gradually increased. These findings were consistent with the findings that the contents of thearubigins and theaflavins were gradually reduced and theabrownin was increased. These results indicate that the degree of fermentation of Pu-erh Tea can be controlled by chromatic value and that Pu-erh Tea quality can be improved by a system with constant temperature and humidity.