Reactivity of monosodium glutamate in meat and its role on lipid and protein oxidative processes

Monosodium glutamate (MSG) is an additive globally used in the food industry as flavor and taste enhancer, responsible for what is known as “umami” taste. This additive is generally recognized as safe by official organizations such as the Food and Drug Administration and the European Commission, and extensive research has been conducted to assess its sensory properties and its lack of toxicological effects when added to food. However, doubts have been raised regarding its long-term consumption safety, as less is known about its influence on the oxidative stability of food products such as meat.

Hence, to explore the impact of MSG on meat quality, we investigated whether MSG fortification of pork burger patties influenced lipid and protein oxidation and Maillard reaction products generation. Therefore, patties with 0-1.2% MSG (w/w) were prepared, stored up to 4 days at 4ºC and cooked in an oven at 180ºC for 15 minutes. GC-MS and 1H-NMR reported a promoting effect on lipid oxidation upon MSG fortification. On the other hand, 2,4-Dinitrophenylhydrazin (DNPH) assay revealed that MSG addition did not influence protein-bound carbonyls, while the analysis of selected advanced glycation end products (AGEs) by LC-MS/MS showed no progression of advanced Maillard reaction stages due to MSG. These results suggest that MSG does not modify protein moieties in pork meat, and therefore does not significantly impact protein quality. Nevertheless, 1H-NMR and LC-MS/MS analysis showed a partial decrease in MSG concentration, confirming its reactivity with meat components. Interestingly, a significant increase (p < 0.05) in Schiff bases content was found due to the highest (1.2%) MSG supplementation, suggesting that Schiff base adducts formation might be linked to its lipid oxidation promoting effect.

In conclusion, this research has uncovered novel insights into the interplay between MSG and pork meat constituents, shedding new light on this additive in terms of food quality.