Flavor enhancement of summer-autumn black tea through synergistic processing with mixed fruit juice: a metabolomics analysis

Tea processed from the leaves harvested in the summer and autumn is often characterized by a pronounced bitterness and astringency, coupled with an aroma profile that lacks complexity. This study aimed to enhance the flavor of summer-autumn black tea by incorporating a mixed fruit juice ( Siraitia grosvenorii and Clausena anisum-olens (Blanco) Merr.) during processing. Its impact was comprehensively assessed based on sensory attributes, physicochemical components, and key volatile and non-volatile substances. The results demonstrated that the addition of the mixed fruit juice significantly enhanced the sensory flavor of the black tea, specifically intensified fruity, woody, and spicy aroma notes. A total of 17 key aroma compounds with OAVs >1 were identified, primarily contributing to honey, floral, woody, and spicy aromas. Metabolomics analysis further revealed that the juice addition significantly elevated the levels of theaflavins, mogrol, apigenin, vitexin, cosmosiin, γ-aminobutyric acid, and coumarin derivatives ( P < 0.001).