Widely Targeted Metabolomics Analyses Provide Insights into the Transformation of Active Ingredients During Drying and the Mechanisms of Color Change for Forest Ginseng (Panax ginseng C. A. Mey. cv. Sativi-nemoralis)

In this study, we investigated the mechanism of conversion of active components as well as the color change of forest ginseng (FG) during the drying process with the self-developed negative-pressure circulating airflow-assisted desiccator (PCAD) drying method, using a widely targeted metabolomics analytical method based on ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). During the drying process, a total of 1862 metabolites were identified in FG, along with 748 differential abundant metabolites (DAMs). Further analysis of the types and metabolic pathways of the DAMs revealed that both primary and secondary metabolites changed by 50-70% moisture content (MC); secondary metabolites dominated with a 30-50% MC, and primary metabolites dominated with a 10-30% MC, which revealed the differences in the transformation of the active ingredients in the drying process. In addition, the results showed the browning characteristics during the drying process. MC-50 and MC-10 showed the smallest and largest color changes, as well as enzyme activities, compared to the other MCs, respectively. As drying proceeded, browning reactions were mainly related to lipid and nucleotide metabolism and phenylpropane and flavonoid biosynthesis. In conclusion, the present study provides theoretical support for the mechanisms of active ingredient transformation as well as the color change of FG during PCAD drying.