Yellow-light combined with high-temperature withering synergistically optimize aroma in summer-autumn black tea

Abstract Summer-autumn black teas frequently exhibit diminished aroma intensity, reducing consumer acceptability. While light-withering technologies improve tea aroma, the combined potential of yellow-light (585–590 nm, 1220–1450 Lux) and high-temperature (32℃, 60% relative humidity) withering (HY) remains unexplored. Sensory and gas chromatography–mass spectrometry (GC–MS) analyses showed HY significantly enhanced floral and sweet-fruity aromas compared to natural withering (CK), yellow-light (YL), or high-temperature (HT) treatments alone. Among 48 volatile aroma compounds (VACs), 11 key odorants (rOAV > 1, VIP > 1) were identified as primary contributors driving the aroma differences observed between treatments. HY achieved peak concentrations of critical floral (trans-β-ionone, linalool, geraniol, nonanal) and sweet-fruity contributors (phenylacetaldehyde, 3-methylbutanal, dimethyl sulfide) in both withered leaves and finished teas, suggesting a synergistic enhancement between yellow-light and high-temperature withering. Metabolic analysis revealed HY coordinately enhanced floral aromas by enhancing the formation of volatiles derived from the methylerythritol phosphate (MEP) pathway and linoleic acid degradation, while promoting amino acid degradation (phenylalanine, leucine, and methionine) to intensify sweet-fruity notes. Overall, this photo-thermal approach (HY treatment) effectively optimizes aroma composition and quality of black tea, providing a theoretical and practical basis for high-aroma tea production and seasonal aroma deficits remediation. Graphical Abstract