Flavor deterioration of liquid endosperm in postharvest tender coconut revealed by LC-MS-based metabolomics, GC-IMS and E-tongue

LC-MS-based non-targeted metabolomics, GC-IMS and E-tongue were employed to study the dynamical changes of the liquid endosperm, normally known as coconut water (CW), in postharvest coconut matured 8 months after full bloom. A total of 61 compounds was identified as differential metabolites responsible for metabolic changes during the whole storage (35 d at 25 ℃) using UPLC-MS/MS, whereas 8 volatiles were considered as the main components contributed to odor deterioration by GC-IMS. E-tongue data showed that bitterness response of CW was enhanced during storage, which was consistent with the variation of some bitter amino acids and epicatechin, while sweetness, sourness and umami exhibited an increased tendency except a decrease at 7 d due to the alteration of phenolic, amino acid, sugar and nucleotide. Postharvest storage displayed a distinct metabolic signature characterized by increased amino acid, nucleotide and sugar metabolisms. These results provided some new insights for biochemical changes of CW inside the postharvest coconuts.