Decoding Taihu Cuizhu tea quality: Multi-omics reveals seasonal and fixation effects

Through an integrated multi-omics approach, this study deciphers how seasonal, microbial, and metabolic factors collectively shape the quality of Taihu Cuizhu green tea. Special-grade autumn teas exhibit superior appearance, aroma, and balanced flavor with reduced bitterness, whereas first-grade spring teas contain higher levels of soluble polysaccharides, polyphenols, and amino acids, contributing to their enhanced sensory quality. Spring teas showed greater microbial diversity, with Sphingomonas (Proteobacteria) promoting the synthesis of flavor compounds such as L-theanine. In contrast, autumn teas accumulated stress-induced alkaloids like cephalotaxine under cooler conditions. Fixation acts as a metabolic switch: optimal results were achieved at 160 °C for special-grade tea and 180 °C for first-grade tea, with spring tea benefiting from longer fixation (8 min) and autumn tea requiring a shorter duration (6 min). These parameters maximized the preservation of catechin and flavonoids while maintaining sensory traits. Spring teas demonstrated more stable microbial communities, strengthened by fixation, with high-temperature fixation (SF180_8) enhancing bacterial interactions and flavonoid biosynthesis. Metabolomic profiling confirmed a seasonal biosynthetic trade-off: Flavonoids dominated in spring, supporting antioxidant capacity, whereas alkaloids accumulated in autumn, enhancing astringency. This multi-omics framework provides a foundation for precision tea production, enabling targeted harvesting and processing strategies to achieve specific quality profiles. Future studies may integrate real-time monitoring and machine learning to optimize and extend this model to other tea varieties and agricultural products.