Microorganisms and Maillard reaction products: a review of the literature and recent findings

Research on the impact of Maillard reaction products (MRPs) on microorganisms has been reported in the literature for the last 60 years. In the current study, the impact of an MRP-rich medium on the growth of three strains of Escherichia coli was measured by comparing two classic methods for studying the growth of bacteria (plate counting and optical density at 600 nm) and by tracing MRP utilisation. Early stage and advanced MRPs in the culture media were assessed by quantifying furosine and N ᵋ -carboxymethyllysine (CML) levels, respectively, using chromatographic methods. These measures were performed prior to and during bacterial growth to estimate the potential use of these MRPs by Escherichia coli CIP 54.8. Glucose and lysine, the two MRP precursors used in the MRP-rich medium, were also quantified by chromatographic means. Compared to control media, increased lag phases and decreased growth rates were observed in the MRP-rich medium for two out of the three Escherichia coli strains tested. In contrast, one strain isolated from the faeces of a piglet fed on a MRP-rich diet was not influenced by the presence of MRPs in the medium. Overall, CML as well as the products obtained by the thermal degradation of glucose and lysine, regardless of the Maillard reaction, did not affect the growth of the three strains tested. In addition, no degradation of fructoselysine or CML was found in the presence of Escherichia coli CIP 54.8.