Abstract: The quality of fresh Tan sheep meat is closely related to the metabolites produced by microbes during chilled storage. Metabolomics can systematically determine the profiles of intracellular and extracellular metabolites systematically and therefore contribute to qualitative and quantitative analysis. This study focused on the metabolomic analysis of microorganisms in tray-packaged Tan sheep meat during chilled storage by gas chromatography-mass spectrometry (GCMS) and on the discrimination of the differences among biological samples with different storage times in order to find out the variables or molecules contributing to these differences. The variable metabolites were mapped to the corresponding metabolic pathways in the major spoilage bacteria Pseudomonas for analyzing the relative intensity of metabolism. The use of pattern recognition mode of orthogonal partial least squares analysis could complete distinguish different storage time groups. The results showed that the metabolism intensity of citric acid cycle, arginine metabolism, alanine, aspartic acid and glutamic acid metabolism and pentose phosphate pathway were relatively high. It is feasible to find out and determine the variable metabolites of microorganisms using GC-MS.

Key words: Tan sheep, microorganism, variable metabolites, gas chromatography-mass spectrometry (GC-MS)