Lipidomics combined with amino acids and their derivatives: Targeted metabolomics analysis for the quality deterioration of coconut water.

A systematic analysis of temporal changes in coconut water quality is essential for coconut industry development. This study elucidated deterioration-related metabolic pathways by integrating targeted lipidomics with amino acids and their derivatives. The content of malondialdehyde gradually increases with prolonged storage time, indicating that lipid oxidation occurs during the storage of coconut water. The results showed that the lipid levels increasing especially phosphatidylserine and free amino acids decreasing over time. A total of 75 differential lipids and 41 differential amino acids and their derivatives were identified during the storage of coconut water, with glycerophospholipid metabolism and aminoacyl-tRNA biosynthesis significantly enriched as the metabolic pathways. Glycerophospholipid metabolism primarily yields sn-glycerol-3-phosphate and 1,2-diacyl-sn-glycerol, which are ultimately broken down through glycolytic pathway and TCA cycle. Succinic acid reached the highest level of 1856.81 ± 113.50 μg/mL in coconut water at 24 h of storage. As a TCA cycle-derived metabolite, its accumulation was associated with pH reduction and oxidative rancidity of coconut water, which suggests that trace lipids and amino acids and their derivatives markedly influence coconut water quality during storage. Correlation results indicate that there are significant correlations among differential lipids and differential amino acids and their derivatives, with negative correlations predominating. The findings indicate that the quality deterioration of coconut water is associated with lipid oxidation and the accumulation of succinic acid.