Influence of Light Quality During Spreading on the Chemical and Aromatic Profile of Summer Green Tea

The use of different light qualities during the spreading stage can influence the flavor of green tea. In this study, freshly harvested leaves were exposed to red (GRL), yellow (GYL), blue (GBL), or natural light (GCK, as the control) throughout spreading. The resulting tea quality was subsequently evaluated through sensory assessment, combined with HS-SPME-GC-MS and UPLC-MS/MS analyses. The results showed that blue light significantly increased free amino acid content and promoted the accumulation of compounds associated with freshness. Yellow light treatment enhanced aroma substances, with 2(5H)-furanone, 5-ethyl-3-hydroxy-4-methyl, benzenemethanethiol, and 3-buten-2-one, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl) detected at the highest levels in this group, contributing to the highest sensory aroma score. In contrast, the GRL group exhibited the lowest levels of aroma compounds, although its sensory score remained relatively high. The GCK group exhibited more pronounced chestnut-like aroma characteristics but received the lowest sensory score. Overall, blue light promotes a fresh and rich taste, whereas yellow light contributes more substantially to the development of aromatic characteristics. These findings indicate that adjusting light quality during the spreading stage can improve the flavor quality, providing a potential strategy for optimizing green tea processing practices.