Scenting parameters affect physicochemical quality, antioxidant capacity, and volatile metabolites of osmanthus white...

This study investigated the effects of scenting cycles, flower-to-tea ratio, and scenting duration on osmanthus white tea quality using an L₉(3³) orthogonal design. Scenting increased water extract, soluble sugars, free amino acids, and DPPH/hydroxyl radical scavenging versus the CK, while polyphenols and caffeine remained stable. HS-SPME-GC-MS identified 137 volatile compounds, with trans-beta-ocimene and 1-hexanol as predominant constituents. OPLS-DA screened 53 key compounds, and volcano plot analysis revealed 70 upregulated and 5 downregulated metabolites. Mantel test uncovered 16 significant correlations between key volatiles and electronic nose sensors, with the strongest association for (5R,8R,8aS)-5-heptyl-8-methyloctahydroindolizine and the W1W sensor (r = 0.846). SVM classification achieved 76.7% accuracy (macro-AUC = 0.922) for predicting scenting cycles, and SHAP analysis identified n-butyl acrylate and linalyl formate as robust discriminatory markers for scenting intensity. Sample No. 8 excelled in sensory quality, while No. 7 exhibited optimal flavor balance. These findings provide theoretical support for industrial-scale osmanthus white tea production.