Deciphering processing parameter optimization and freshness-astringency balance mechanism of Meitan Cuiya tea by integrating multi-omics and WGCNA

Summer tea leaves of Meitan Cuiya (MTCY) exhibit low amino acid content and high bitter compounds, which restrict its quality and utilization. However, the molecular mechanisms by which processing regulates metabolite conversion and sensory quality in summer MTCY remain unclear. This study investigated the effects of fixation, shaping, and drying on sensory quality and metabolite profiles, and optimized processing parameters using sensory evaluation, electronic tongue, gas chromatography–mass spectrometry (GC-MS), broad-target metabolomics, and weighted gene co-expression network analysis (WGCNA). The optimal conditions were fixation at 180 °C for 4 min, shaping at 80 °C for 4 min, and drying at 130 °C for 6 min. Under these parameters, the electronic tongue showed an umami score of 9.14 and an astringency score of -6.98, with a sensory score of 89.8, featuring chestnut aroma, fresh and mellow taste. Metabolomic analysis indicated that the optimized process regulated flavonoid biosynthesis. WGCNA revealed high correlations (Pearson r > 0.96) between metabolic modules and favorable sensory attributes. These findings clarify the metabolic mechanisms for quality improvement and provide a scientific basis for the standardized production of summer green tea. • Optimized key processes enhance summer Meitan Cuiya quality. • Multi-omics reveals metabolic pathways in tea quality formation. • WGCNA links metabolic modules to sensory traits like umami. • Key volatiles and metabolites define chestnut aroma and flavor.