Aroma profiling using GC E-nose to trace origin of polygonati rhizoma species and quantify the effect of using ‘nine steaming and nine sun drying” processing

Aroma evolution during the traditional Nine Steaming and Nine Drying (NSND) process is essential to establish quality control and authentication of Polygonatum rhizome (PR) species, yet the underlying chemical mechanisms underlying changes remain poorly characterized. Using a flash GC-<i>E</i>-nose, we profiled volatile transitions of four PR species across ten NSND stages and tentatively identified 71 compounds. Distinct aroma trajectories were observed: early-stage loss of green aldehydes and alcohols reflected suppression of lipid-oxidation pathways, whereas later-stage increases in roasted, aromatic, and sulfur-derived notes were consistent with progressive Maillard reactions, sugar fragmentation, and Strecker degradation. Species-specific differences, including ester, ketone, and phenolic formation, further suggested variations in precursor pools and thermal reactivity. Multivariate analyses (ANOVA, PCA, HCA) clearly discriminated species and steaming stages, revealing consistent chemical transformation patterns. These mechanistic insights provide foundational volatile profiling knowledge that will support future development of aroma-based tools for PR quality evaluation and authentication.