A NMR-based metabolomics approach for reducing food losses: the example of minced pork meat

In Europe, the losses of initial meat production represent 20% and more than half of this occurs at animal production, slaughtering, processing and distribution step. In order to control food waste, studies have highlighted the importance of monitoring the microbial diversity of food products because spoilage by bacteria that contaminate the food matrix is a major issue. As such, the combination of metabolomics data with other complementary approaches (classical microbiology and quality parameters) can gives the opportunity to gain deeper insights into and have a better comprehension of the spoilage mechanisms. The aim of the current study was to assess meat spoilage through the evolution of bacterial counts and changes in the metabolic profile of minced pork meat using Nuclear Magnetic Resonance (NMR) based metabolomics. Microbiological assessment, pH measurements, gas composition and metabolomics analysis were carried out in meat samples stored under food wrap and under modified atmosphere packaging (70% O2 – 30% CO2) at 4, 8 and 12°C during 13 days. All samples were irradiated and then inoculated separately with three dominant bacterial species: Brochothrix thermosphacta, Leuconostoc gelidum and Pseudomonas fragi. For all conditions, non-inoculated samples were also stored. Analysis were carried out at day 0 and at day 13 for metabolomics analysis, and each day for all others measurements. The multivariate analysis (PLS-DA) reveals a clear discrimination between: (i) the non-inoculated product at day 0 and at day 13, (ii) the inoculated and non-inoculated samples, (iii) the type of bacterium, and (iv) the packaging conditions. It can be observed that the type of bacterium inoculated had a higher impact on the metabolome than that the packaging conditions. Moreover, some metabolites are significantly increased: acetate and glycerol for B. thermosphacta, betaine and lactate for L. gelidum, threonine and glycine for P. fragi. Exploration of the correlations of NMR-based metabolomics results with others microbial parameters suggested their use as possible spoilage tool to provide information on minced pork meat spoilage and to follow intrinsically the evolution of the metabolomics pattern linked to a specific bacterium in a complex bacterial ecosystem.