Metabolic dynamics of litchi pericarp and pulp during browning: Unraveling differential profiles through temporal clustering and untargeted metabolomics.

Litchi, valued for its vibrant appearance and nutritional content, undergoes rapid browning of the pericarp (PE), reducing its market value. However, the browning mechanism and the impact of browning on the pulp (PU) are not fully understood. This study, litchi fruits were considered at five browning stages. Untargeted LC-MS metabolomics and cluster analysis revealed more pronounced browning-related metabolic changes in the PE than in the PU, as shown by greater separation in PE via principal component analysis. Overall, 53 differential metabolites in PE and 24 in PU were characterized, including flavonoids and lipids. The correlation analysis results revealed that the metabolites strongly associated with the browning process in the PE were primarily lipid compounds. Pathway analysis indicated that PE browning was associated with flavonoid pathway and lipid metabolism. These findings offered insights into litchi browning metabolism and a basis for improving PE browning delay and post-harvest preservation.