Quality Evolution of Pu-Erh Raw Tea over 1–22 Years of Aging

Long-term aging transforms the sensory quality of raw Pu-erh tea, but the temporal coordination between taste-related and aroma-active compounds remains unclear. Here, raw Pu-erh teas aged for 1–22 years, produced in the same region and stored under consistent conditions, were characterized using sensory evaluation, targeted analysis of non-volatile constituents, headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry, relative odor activity values (ROAVs), and multivariate statistics. Aging shifted the sensory profile from fresh, strong, and astringent to mellow and aged, accompanied by a change in liquor color from yellow-green to orange-red. Non-volatile profiles resolved four aging stages (1–4, 6–10, 14–18, and 19–22 years), whereas key aroma-active compounds resolved three stages (1–10, 14–19, and 20–22 years). Tea polyphenols, catechins, and free amino acids generally declined, while theabrownins, thearubigins, gallic acid, and selected flavonoids accumulated. Among 523 detected volatile compounds, 39 exhibited ROAVs ≥ 1; β-ionone and (E)-2-nonenal formed a persistent floral–woody aroma backbone, while stage-specific changes increasingly favored resinous, camphoraceous, roasted, and aged notes. Notably, differences in non-volatile composition weakened after 14 years, whereas aroma profiles continued to reorganize. This asynchronous evolution constitutes the central finding of this study, demonstrating that taste-related composition approaches relative stability before aroma maturation is complete and providing a chemical basis for aging-stage classification and quality evaluation.