Metabolomics and electronic tongue analysis show taste differences in Juhong tea from various black tea sources

Juhong tea is an innovative blend of citrus peel and black tea characterized by a multifaceted flavor system and synergistically enhanced bioactive constituents. Here, the taste profiles, metabolic variations and antioxidant ability were comprehensively compared and characterized across four Juhong teas derived from diverse raw materials: traditional Juhong tea (TJH), single-bud Juhong tea (BJH), wild Juhong tea (WJH), and shaded Juhong tea (SJH), with both commonalities and distinctions highlighted. Sensory evaluation showed that BJH received the highest average overall sensory score (8.05), driven by a rich profile of amino acids (totaling 20.56 mg/g), whereas TJH exhibited superior sweetness (8.85) in electronic tongue analysis due to higher soluble sugar and theaflavin concentrations. Widely targeted metabolomics identified 520 nonvolatile metabolites across the samples, with 193 key differential metabolites screened via OPLS-DA by the criteria of variable importance in projection (VIP) > 1, p < 0.05, and |log2(fold change) | > 1. The common abundant metabolites, particularly theanine, 2-aminoisobutyrate, tangeretin, and hesperidin, synergistically shape the characteristic umami, sweet, and citrus-like flavor of Juhong teas. Furthermore, correlation analysis indicated that polyphenols, amino acids, and theaflavins jointly drive the antioxidant properties of Juhong tea. Collectively, these findings revealed the chemical basis of the Juhong tea flavor, providing a theoretical framework for quality control and processing optimization of citrus-tea composites.