Metabolomics Study of Browning Mechanism in Eggplant Fruits

Abstract

Background: Fresh-cut fruits and vegetables is a emerging type of fruits and vegetables processing products for consumers to eat immediately or for the catering industry. Enzymatic browning is one of the crucial problems compromising the flavor and texture of fresh-cut fruit and vegetables. Eggplant is a common vegetable, which is favored by consumers. Accordingly, we used an untargeted metabolomics approach based on liquid chromatography-mass spectrometry (LC-MS) to explore the browning mechanism in peeled eggplant ( Solanum melongena L . ). Results: Metabolomics revealed several hundred differential metabolites, including lipids, phenols, sugars and fatty acids. The content of these metabolites changed dynamically as the peeled time increased. The content of polyphenols, especially chlorogenic acid, increased significantly, suggesting that the main substrate for enzymatic browning in eggplant is chlorogenic acid. Furthermore, all the differential metabolite were mapped to KEGG pathway, revealing significant differences in linoleic acid metabolism, tyrosine metabolism ，glutathione metabolism, pentose phosphate pathway, tropane, piperidine and pyridine alkaloid biosynthesis, phenylpropanol metabolism and glycosylphosphatidylinositol(GPI)-anchor biosynthesis over time. Therefore, we speculate that some metabolic pathways that are closely connected with respiration, glycolysis, ATP synthesis, and phenolic synthesi are disturbed after peeling, under the action of enzymes, eventually leading to browning. Conclusions: We established an untargeted metabolomics method based on LC-MS technology to explain the mechanism of eggplant browning, which may lay the foundation for better understanding the mechanism of browning during the fruits and vegetables deeply processing, and furnish new ideas and perspectives for understanding fruit and vegetable browning in the future.