Effects of Early Light-Quality Pretreatment During Withering on the Taste and Aroma Quality of Autumn White Tea

Abstract

This study establishes early light-quality pretreatment as an effective strategy to enhance the flavor of autumn white tea. A multi-platform framework integrating sensory evaluation, electronic tongue (E-tongue), electronic nose (E-nose), high-performance liquid chromatography (HPLC), ultraviolet-visible (UV-Vis) spectrophotometry, and gas chromatography-ion mobility spectrometry (GC-IMS) was employed to correlate sensory perception with chemical composition. Blue-light pretreatment markedly improved sweetness, umami, and a more coordinated aroma profile characterized by sweet/caramel-like and roasted notes, while reducing bitterness, astringent aftertaste, and green-note-related characteristics. Compared with red- and yellow-light pretreatments, blue light showed lower instrumental bitterness, and it also reduced residual aftertaste-related responses and green-note-related volatile characteristics. These changes were associated with increased total free amino acids and soluble sugars, altered catechin composition, and reduced green-note volatiles. Yellow light preferentially enhanced floral- and fruity-related volatile profiles, whereas red light showed limited overall benefits. Multivariate and Mantel analyses supported significant associations between chemical profiles and sensor responses, including epigallocatechin gallate (EGCG)–astringency and epicatechin gallate (ECG)–aftertaste-B. Collectively, blue-light pretreatment may improve autumn white tea flavor through coordinated changes in taste-active compounds and volatile metabolites, providing a practical basis for precision control of white tea quality.