Insights into potential flavor-active peptides and taste-related compounds in Longjing teas: A comparative study of 'Longjing 43' and 'Qunti' cultivars.

Longjing tea is well-known for its exceptional umami/mellow flavor, but the complexity of interactions among chemical compositions has impeded in-depth understanding. This study comprehensively compared the taste contributors in 'Longjing 43' (LJ43) and 'Qunti' (QT). Peptidomics revealed 865 identified water-soluble peptides in QT, and 497 in LJ43, with 44 umami peptides predicted. Potential umami peptide-T1R1/T1R3 complexes were further modeled using AlphaFold 3. LJ43 had higher levels of theanine (>18 mg/g), and glutamine (∼4 mg/g) compared to QT. Similar amounts of flavan-3-ols (>150 mg/g), particularly EGCG (>60 mg/g) and ECG (>30 mg/g) were determined in LJ43 and QT. Moreover, Longjing teas' characterized flavor contributions by macromolecules (peptides), and small molecules (amino acids, catechins, saccharides, and Maillard reaction products) were integrated. These insights will greatly expand tea flavor chemistry and provide promising approaches promotion premium Longjing teas.