Characterization of key aroma components of low-caffeine, high-theobromine, and high-polyphenol Camellia yungkiangensis ‘Rongjiangcha’ tea

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Camellia yungkianensis H. T. Chang ‘Rongjiangcha’ (RJC) is a rare tea germplasm with high polyphenols, elevated theobromine, and low caffeine, yet its aroma profile remains unclear. Here, volatile metabolites from fresh leaves, black tea, and white tea of RJC and three conventional cultivars were analyzed by HS-SPME-GC-MS. A total of 1,249 volatiles were identified, dominated by terpenoids and esters. Integration of relative odor activity values (rOAV > 1) with OPLS-DA revealed 250 and 245 key volatile compounds in RJC black and white teas, respectively. Core compounds—geraniol (rOAV > 100), β-ionone (rOAV > 50), and non-8-enal (rOAV > 10)—contributed to characteristic floral-fruity notes. KEGG analysis showed phenylalanine metabolism and monoterpenoid biosynthesis enriched in black tea, and sesquiterpenoid biosynthesis in white tea. Enzyme regulation (β-glucosidase, PAL) during processing was critical for aroma formation. This work elucidates volatile compound composition and metabolic pathways in RJC, offering a basis for processing optimization, product innovation, and breeding of low-caffeine teas with distinctive sensory quality. • Aroma compounds of Camellia yungkianensis (RJC) teas were characterized • Key differential metabolites for RJC compared with common cultivars were identified • Floral, fruity, and sweet aroma-active compounds were dominant in RJC teas • RJC teas had distinct terpenoid and phenylalanine-derived metabolic pathways • Findings will aid breeding and processing of superior tea with health benefits

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