Sourness signature during Prunus mume fruit development: Integrative insight from metabolomics, organic acid profiles, E-tongue, and computational binding simulation.

Prunus mume (P. mume) fruit is sharply sour, yet the sourness signature during P. mume fruit development remains unclear. Here, integrated metabolomics (LC-MS/MS for non-volatiles, GC-MS for volatiles), targeted organic acid profiling, E-tongue, and computational simulations were employed to decipher the sourness signature. A total of 2703 non-volatile and 59 volatile metabolites were identified, and 47 organic acids were quantified. During development, total organic acids increased by 374.87%, dominated by citric acid (90.61% at maturity) with malic acid as a key co-contributor. Sourness intensity rose by 49.80% and correlated strongly with total acids and citric acid. Molecular docking revealed that acid anions, especially citrate, interact with sourness receptors (OTOP1/PKD2L1), potentially enhancing perception. This study clarifies the chemical drivers and receptor-interaction patterns underlying the development of the sourness signature in P. mume fruit.