Study on the correlation between external traits and intrinsic quality of Pseudostellariae Radix based on intelligent sensory evaluation and DESI-MSI technology.

Currently, the quality analysis methods for Pseudostellariae Radix (PR) are often time-consuming, costly, and operationally complex, which hinders growers, distributors, and consumers from making rapid, preliminary judgments regarding its intrinsic quality. This study established methods for the objective quantification of external trait indicators of PR using an electronic tongue, a colorimeter, and an ultra-fast gas chromatography electronic nose (UF-GC-EN). The intrinsic quality of PR was evaluated using heterophyllin A (HA), heterophyllin B (HB), pseudostellarin G (PG), total polysaccharides (TPS), total saponins (TSS), and water-soluble extractives (WSE) as key indicators. The spatial distribution of cyclic peptide active ingredients and plant hormones in the swollen parts of PR was visualized using desorption electrospray ionization-mass spectrometry imaging (DESI-MSI). The results showed that, from the 29 trait parameters, 12 key trait parameters with the potential for quality discrimination were identified: diameter at the thickest part (DTP), single root weight (SRW), number of roots per 50 g (NPG), saltiness, yellowness index (YI), lightness (L*), red-green axis (a*), yellow-blue axis (b*), chroma (C*), hue angle (h°), and peaks P4 and P12. Specifically, a deeper yellow color of PR was associated with a higher WSE content. The degree of root tuber swelling showed a significant positive correlation with TPS content, while exhibiting significant negative correlations with the contents of HB, HA, PG, and TSS. The saltiness value displayed highly significant positive correlations with HA and PG contents, but a highly significant negative correlation with WSE content. In the odor component fingerprint, two chromatographic peaks, P4 and P12, were both identified as 1-Hexen-3-ol, which possesses a grassy odor, and their peak areas showed highly significant negative correlations with the contents of both HA and PG. HA, HB, and PG were distinctly distributed in the phloem and periderm of the swollen parts of PR, while zeatin was concentrated in the cambium. By analyzing and validating the correlations between traits and quality, this study provides a statistical reference and demonstrates potential application prospects for the rapid assessment of the intrinsic quality of raw medicinal materials, including PR.