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

## TL;DR

This study shows how temperature controls the flavor and health benefits of dark tea by influencing the metabolism of a key fungus during fermentation.

## Contribution

The study reveals temperature as a precise metabolic switch in Aspergillus tubingensis during dark tea fermentation.

## Key findings

- Low temperatures produce a mushroom-like aroma dominated by 1-octen-3-ol.
- High temperatures yield a floral-woody profile via accumulation of β-ionone.
- Temperature regulates the production of lovastatin and balances flavonoids with carbohydrates for taste.

## Abstract

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 Aspergillus tubingensis 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 β-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 A. tubingensis. 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.

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•Temperature switched metabolic output of Aspergillus tubingensis.•Temperature controlled aroma: low for mushroom, high for woody.•Temperature balanced flavonoids and sugars to optimize taste.•The production of lovastatin by A. tubingensis was regulated by temperature.

Temperature switched metabolic output of Aspergillus tubingensis.

Temperature controlled aroma: low for mushroom, high for woody.

Temperature balanced flavonoids and sugars to optimize taste.

The production of lovastatin by A. tubingensis was regulated by temperature.