Fatty acid degradation driven by heat during ripening contributes to the formation of the “Keemun aroma”

Ripening refers to the process of chemical change during the refinement of Keemun black tea (KBT) and is crucial in the formation of Keemun Congou black tea’s quality. In this study, the aroma composition of KBT during the ripening was analyzed. Sensomics indicated that ripening strengthened the coconut and fatty aroma of KBT and contributed to the decrease of green aroma substances, resulting in a shift of the overall aroma type of KBT to an integrated aroma profile, which was consistent with sensory evaluation. Changes in fatty acid content and the results of in vitro addition simulation tests confirmed that heat causes highly degradation of fatty acids into fatty aroma volatiles, which is a key driver of the formation of “Keemun aroma” quality. This study revealed the mechanism behind the formation of KBT’s integrated “Keemun aroma” quality and the mode of thermal degradation of major fatty acids.