Addition of monosodium glutamate can reduce the oxidative stability of lipids in pork burger patties via early-stage Maillard reaction products formation

Monosodium-L-glutamate (MSG) is an additive commonly used worldwide to increase the palatability of many foods, due to its popular umami flavor enhancing properties. While research has extensively focused on evaluating its safety and sensory properties, no prior studies have provided a comprehensive evaluation of the impact of MSG on the oxidative stability of food. Thus, this study investigated, for the first time, the influence of MSG supplementation (0.4 % and 1.2 %, w/w) on the progress of lipid and protein oxidation as well as the Maillard reaction in pork burger patties stored at 4 °C up to 4 days and cooked in an oven at 180 °C for 15 min. Analysis of lipidic extracts from the meat patties revealed the promotion of lipid oxidation during cooking due to 1.2 % MSG addition (e.g. > 53 % mean increase in alkanals), as determined by mass spectrometry and proton nuclear magnetic resonance. Conversely, 1.2 % MSG addition had no general impact on the formation of protein carbonyls and advanced glycation end products, although it promoted the generation of Schiff bases. This effect was attributed to the formation of N-dihydroxypropylideneglutamic acid, which was significantly correlated with the rise of secondary lipid oxidation products, suggesting that the prooxidant role of MSG might be related to the formation to this early-stage Maillard reaction product. Therefore, this study evidenced the interrelationship between oxidative processes and the Maillard reaction during MSG supplementation, highlighting the need for further research on the fate of this additive to ensure food quality and safety.