Effects of Optimized Key Processing Parameters on Macro-Compositions and Volatile Organic Compounds in High-Altitude...

High-altitude environments provide a favorable basis for tea quality formation, but suitable processing parameters for high-altitude Oolong Tea (HAOT, Camellia sinensis (L.) O. Kuntze) remain unclear. This study optimized key processing parameters for HAOT using a three-factor, three-level orthogonal design involving withering method, shaking intensity and standing time. Sensory evaluation, quantitative descriptive analysis (QDA), macro-compositions determination, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS), multivariate statistics and correlation analysis were used to clarify quality differences and their chemical basis. Leaf anatomical observation showed that high-altitude fresh leaves had a thicker cuticle and more compact mesophyll structure, suggesting the need for targeted processing regulation. Range analysis indicated that shaking intensity had the largest R value for sensory scores, followed by withering method, whereas standing time showed a comparatively small R value. The favorable combination was combined withering, heavy shaking (6 rounds) and 60 min standing, hereafter referred to as FHM. FHM showed the highest floral and fruity aroma scores and produced a mellow, full-bodied taste with a sweet aftertaste. It also contained significantly higher flavonoid and soluble sugar levels than the other processing combinations. A total of 65 volatile organic compounds were detected, with terpenoids and esters as the dominant classes. ROAV analysis identified geraniol, linalool, β-ionone, (E)-nerolidol and benzaldehyde as representative major aroma-active compounds, while geraniol and linalool were especially prominent in FHM. Correlation analysis further linked flavonoids and soluble sugars with positive taste attributes, and linalool and geraniol with floral-fruity aroma. These results provide a practical basis for optimizing HAOT processing and improving product quality.