Temperature regulates flavor and bioactivity in dark tea fermentation: Insights from an Aspergillus tubingensis single-strain model

Temperature acts as a master regulator of microbial metabolism in dark tea fermentation, but how to precisely steer this process to craft flavor profiles remains a significant challenge. The metabolic fingerprint of <i>Aspergillus tubingensis</i> during dark tea fermentation under varying temperatures was decoded by utilizing HS-SPME-GC-MS and UHPLC-Q-Exactive HF/MS techniques. The results revealed that temperature acts as a precise metabolic switch. Low temperatures produced a mushroom-like aroma profile dominated by 1-octen-3-ol at dark tea fermentation, while high temperatures yielded a floral-woody profile via massive accumulation of <i>β</i>-ionone. This temperature-dependent control extended to non-volatile compounds, modulating taste by balancing flavonoid degradation with carbohydrate metabolism. Critically, temperature significantly regulated the production of lovastatin by <i>A. tubingensis</i>. This study not only provides a clear metabolic blueprint for understanding the dark tea fermentation but also offers a theoretical basis for the targeted regulation of tea quality via precise temperature control.