ABSTRACT
ObjectiveTo analyze the dynamic changes of the main chemical components and color characteristics of Polygoni Multiflori Radix（PMR） during the process of ancient classical nine-time repeating steaming and sun-drying， and to explore the correlation between the changes. MethodHigh performance liquid chromatography（HPLC） was used to determine the contents of gallic acid， stilbene glycoside， emodin-8-O-β-D-glucoside， physcion-8-O-β-D-glucoside， emodin and physcion in PMR during the process of nine-time repeating steaming and sun-drying， and electronic eye technology was used to objectively characterize the color of PMR during the process. Partial least squares（PLS） was used to analyze the correlation between the content of main components and the color characteristics. ResultDuring the nine-time repeating steaming and sun-drying process of PMR， the content of gallic acid gradually increased with the increase of steaming and sun-drying times， and the contents of other components showed fluctuating changes， with an overall decreasing trend in the contents of stilbene glycoside， emodin-8-O-β-D-glucoside and physcion-8-O-β-D-glucoside， and an overall increasing trend in the contents of emodin and physcion. The results of electronic eye analysis showed that the color of PMR became dark， red and blue in the process of nine-time repeating steaming and sun-drying. The results of hierarchical cluster analysis（HCA） and principal component analysis（PCA） of the contents of six main components and the colors showed that the samples steamed and sun-dried for one to four times could be grouped into one category， the other five categories of samples could be grouped into another category. Gallic acid and stilbene glycoside were significantly correlated with the color indexes of PMR during the process of nine-time repeating steaming and sun-drying. ConclusionThe general changes of material basis and color characteristics of PMR during the process of ancient classical nine-time repeating steaming and sun-drying have certain rules， and the establishment of the correlation model between color and index components can realize the judgment and quality evaluation of processing degree of PMR decoction pieces.
ABSTRACT
ObjectiveTo analyze the flavor substances and change rules of Rhei Radix et Rhizoma during the process of nine-time repeating steaming and sun-drying. MethodThe flavor response values of Rhei Radix et Rhizoma samples were obtained by using PEN3 electronic nose system. The data were processed and analyzed by principal component analysis （PCA）， linear discriminant analysis （LDA） and Loadings analysis. ResultRhei Radix et Rhizoma processed with nine-time repeating steaming and sun-drying could be effectively distinguished into two categories as the sixth sample was the turning point. The samples steamed and dried for one to five times could be grouped into one category， the other four samples were obviously distinguished from them. The main flavor components reached the maximum response in the sample processed with six-time repeating steaming and sun-drying， and its response value of inorganic sulfur compounds was about 2.7 times that of the sample processed with one-time repeating steaming and sun-drying. In addition， compared with the raw products， the flavors of Rhei Radix et Rhizoma processed with nine-time repeating steaming and sun-drying and wine stewing changed significantly， and the response value of inorganic sulfur compounds in sample processed with nine-time repeating steaming and sun-drying was about 2.2 times that of raw products. From the perspective of flavor analysis， the response values of inorganic sulfur compounds and nitrogen-oxygen compounds in sample processed with nine-time repeating steaming and sun-drying were higher than those of wine-stewed products， and the two were not completely equivalent. ConclusionElectronic nose technology preliminarily clarifies the dynamic change rules of the flavor of Rhei Radix et Rhizoma during the process of nine-time repeating steaming and sun-drying from the flavor characteristics， and clarifies the difference between products processed with nine-time repeating steaming and sun-drying and wine-stewed products from the odor characteristics， which lays a foundation for revealing the processing principle of Rhei Radix et Rhizoma processed with nine-time repeating steaming and sun-drying.