乌梅炭炮制过程中颜色与内在质量的相关性及其炮制终点研究

Study on the correlation between color and inner quality during the processing of Prunus mume carbon and its processing end point

目的 研究乌梅炭炮制过程中颜色与内在质量的相关性,为乌梅炭炮制终点的确定提供参考。方法 利用色差仪对乌梅炭粉末进行色度值测定,选择水分、水溶性浸出物、枸橼酸和鞣质含量对乌梅炭进行内在质量测定,分析不同炮制时间下乌梅炭色度值、水分、水溶性浸出物、枸橼酸和鞣质含量的动态变化趋势,对颜色和上述指标含量进行相关性分析,建立内在质量-色度值回归方程。同时结合主成分分析(PCA)、层次聚类分析(HCA)和偏最小二乘法判别分析(PLS-DA)法分析乌梅炭不同炮制时间的差异,以确定其炮制终点。结果 随着炮制时间的延长,样品颜色逐渐加深;样品色度值L*与E*先升高后下降,色度值a*与b*下降,最终均趋于稳定;样品中水溶性浸出物、枸橼酸与鞣质含量均呈先升高后下降的趋势,样品中水分含量随炮制时间的延长而下降,最后趋于稳定。相关性分析结果显示,水分、水溶性浸出物、枸橼酸、鞣质含量与L*、a*、b*、E*均呈显著正相关(P<0.001)。PCA及HCA结果显示,不同炮制时间的乌梅炭饮片可聚为2类:0~30 min炮制样品与40~60 min炮制样品。PLS-DA发现,水分和水溶性浸出物是乌梅炭炮制过程中的重要质量指标,b*是乌梅炭炮制过程中的重要色度指标。炮制50 min和60 min样品的色度值无明显差别,炮制60 min样品的水分、水溶性浸出物、枸橼酸与鞣质含量小于炮制50 min的样品。结论 乌梅炭颜色与内在质量具有一定相关性,乌梅炭的炒制应以40~50 min为宜。

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, watersoluble 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, watersoluble 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.