Molecular mechanism of lipid transformation in cold chain storage of Tan sheep.

Cold chain (-20 °C) is one of the main transportation methods for storage of Tan sheep products. Lipids (66) in seven subclasses involved in sphingolipid, glycerophospholipid and fatty acid degradation metabolism were quantified in Tan sheep under cold chain storage, including fatty acyl carnitines, phosphatidylcholine (PC), lysophosphatidylcholine (LPC), phosphatidylethanolamine (PE), ceramides, sphingomyelin (SM) and lysophosphatidylethanolamine (LPE). Lipid transformation and molecular mechanism analyzed using fragmentation mechanisms and UHPLC-Q-Orbitrap MS/MS combined with lipidomics approaches determined transient increases of certain PC, PE and fatty acyl carnitine during the first 12 days of cold storage, subsequent declines of SM, PC, PE and fatty acyl carnitine, as well as increases of ceramide, LPC and LPE (24 days). These results offered insights into lipid transformation and quality of Tan sheep during cold chain storage.