Mechanism of pyrazines and thioethers formation promoted by high oxygen concentration in the methionine-glucose Maillard reaction system

Background: The typical aroma compounds in methionine-glucose Maillard products often undergo further degradation and polymerization during storage and thermal processing, leading to flavor dispersion and aroma distortion. It is crucial to identify measures that enhance typical aroma substances in such flavor matrices.

Results: The effect of oxygen on the flavor formation of methionine-glucose thermal reaction system was explored by determining typical flavor substance contents and flavor differences. Compared with the oxygen concentration in the air (21%), a high oxygen concentration (30% and 40%) effectively promoted the formation of typical flavor substances. Pyrazines increased by 44% and thioethers increased by 13%. The reaction process and the content of key substances were both measured to explain the involvement of oxygen. It was found that high oxygen concentration increased the reaction efficiency of glucose and methionine and promoted the formation of α-dicarbonyl compounds, including glyoxal, methylglyoxal and 3-deoxyglucosinone. Moreover, a glyoxal-methylglyoxal-methionine model system was established to verify the effect of oxygen intervention on the formation of pyrazines and thioethers generating from α-dicarbonyl compounds. It was confirmed that a high oxygen concentration promoted the consumption of glyoxal and methylglyoxal, which were more readily converted into pyrazines and thioethers without forming melanoidins.

Conclusion: A high concentration of oxygen promoted the formation of pyrazines and thioethers during the Maillard reaction of methionine and glucose, and effectively inhibited the occurrence of browning. The present study provides a new concept for the typical flavor enhancement of methionine-glucose Maillard reaction products. © 2024 Society of Chemical Industry.