RESUMEN
OBJECTIVE To study the correlation between color and inner quality during the processing of Prunus mume carbon， and provide reference for the determination of processing end point of P. mume carbon. METHODS The chromaticity value of P. mume carbon powder was measured by colorimeter， and the inner quality of P. mume carbon was measured by selecting the contents of water， water-soluble extract， citric acid and tannin. The dynamic change trend of the chromaticity value， water， water- soluble extract， the contents of citric acid and tannin in P. mume carbon under different processing time was analyzed. The correlation between color and the above indexe contents was analyzed， and the regression equation of inner quality-chromaticity value was established. Combined with principal component analysis （PCA）， hierarchical cluster analysis （CA） and partial least squares discriminant analysis （PLS-DA）， the difference of P. mume carbon at different processing times was analyzed to determine the processing end point. RESULTS With the extension of processing time， the sample color gradually deepened； the chromaticity values L* and E* of the samples increased at first and then decreased， the chromaticity values a* and b* decreased， and finally all tended to be stable. The content of water-soluble extract， citric acid and tannin in the sample increased at first and then decreased， the water content of the sample decreased with time and finally stabilized. Correlation analysis showed that water， water-soluble extract， citric acid and tannin were positively correlated with L*， a*， b* and E*（P＜0.001）. PCA and HCA showed that P. mume carbon under different processing time could be clustered into two categories： the processed samples of 0-30 min and those of 40-60 min. PLS-DA showed that water and water-soluble extract were important quality indexes and b* was an important chrominance index in the processing of P. mume carbon. The chromaticity value of the samples processed for 50 min and 60 min were not significantly different. The contents of water， water- soluble extract， citric acid and tannin in the samples processed for 60 min were less than those processed for 50 min. CONCLUSIONS There is a certain correlation between the color and the inner quality of P. mume carbon. The processing time of P. mume carbon should be 40-50 min.