Seasonal and processing differences in nonvolatile compounds and volatile aroma of teas from Zhaoyuan, China: insight into “spring green, summer black, autumn dark” quality pattern

Targeting northern marginal tea regions (37°N, Zhaoyuan, China), this study uniquely integrates seasonal processing (spring green, summer black, autumn dark tea) with chemical-sensory analyses on a single Camellia sinensis garden, filling the gap in volatile aroma compound (VAC) profiles of seasonally processed northern teas. Sensory traits diverged by type: SGT had the highest water extract, free amino acids and theanine; SBT the highest polyphenols; ADT the lowest polyphenols (microbial degradation). GC × GC-Q-TOFMS identified 357 VACs (key ROAV>1 compounds varied). Climate regulated precursors, processing drove metabolism, with strong nonvolatile-volatile correlations. Findings validate the seasonal quality pattern and optimize local tea utilization. • Validates 37°N seasonal processing for marginal regions. • GC × GC-Q-TOFMS identifies 357 VACs. • Climate-processing synergy in aroma correlations. • 37°N terroir elucidated for geographical indication. • 30–40% income boost via industrial strategies.