Ultra‐High‐Performance Liquid Chromatography‐High‐Resolution Mass Spectrometry Coupled with Multivariate Analysis Deciphers the Dynamic Transformation of Ginsenosides and the Enhancement of Antioxidant Activity in Nine‐Steaming‐Nine‐Drying Black Ginseng

Black ginseng, produced through the traditional nine-steaming-nine-drying process, exhibits enhanced pharmacological activity compared with unprocessed ginseng. This study investigated the dynamic changes in ginsenoside composition and antioxidant activity during steam-drying using a non-targeted metabolomics approach based on ultra-high-performance liquid chromatography-mass spectrometry. A total of 73 ginsenosides were identified, among which 47 differential markers were screened by principal component analysis and partial least squares discriminant analysis. The relative quantification of 29 key markers revealed distinct transformation patterns of ginsenosides during processing. Antioxidant capacities, evaluated by 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), and Ferric Reducing Ability of Plasma (FRAP) assays, showed trends consistent with changes in total ginsenoside content. The results elucidate the transformation pathways of major ginsenosides during steam-drying and provide a theoretical basis for process optimization and quality control of black ginseng-derived products.