Lipidomics reveals temporal changes in pecan kernel lipids during storage with or without sodium erythorbate treatment

Abstract

Pecan nuts are rich in lipids that often degrade during storage; however, the progressive transformation of lipids in this process is still unclear. Therefore, high-throughput lipidomics was carried out based on ultrahigh-performance liquid chromatography coupled with a Q Exactive mass spectrometer (UPLC-Q Exactive MS). A total of 1451 lipid species from 5 classes and 24 subclasses were identified. Oxidized (Ox) phospholipids, fatty acid ester of hydroxy fatty acids, and N-oleoyl leucine were identified in pecan for the first time. The intensities of all diacylglycerols, phosphatidic acids (PAs), fatty acids, and fatty acid ester of hydroxy fatty acids increased obviously with pecan storage. Lipid hydrolysis was prevalent in both the control group and the treatment group during storage. Oxidation mainly did not occur on glycerolipids and glycerophospholipids in pecan. Lipids might be hydrolyzed first and released free fatty acids, which were then oxidized. Sodium erythorbate treatment could effectively delay the increase in peroxide value and the degradation of triacylglycerols. Differentially abundant lipids (DALs) were selected and could be used as markers for evaluating the deterioration of pecan during storage. Possible mechanisms of lipid degradation in pecan oil bodies during storage were also proposed.