Kinetic study of high-intensity ultrasound-assisted Maillard reaction in a model system of d-glucose and glycine.

A kinetic model for a high-intensity ultrasound-assisted Maillard reaction model system of d-glucose and glycine was proposed; activation energy (Ea) for each reaction step was calculated. Results showed that the generation of dicarbonyl compounds was significantly promoted by high-intensity ultrasound (e.g. Ea values for 1-deoxyglucosone were 60.9 ± 9.7 kJ mol-1 and 105.5 ± 9.9 kJ mol-1 in ultrasonic and thermal Maillard reaction, respectively), which resulted in a significantly higher concentration of colored and volatile Maillard reaction products generated in ultrasound-assisted Maillard reaction compared with that in thermal Maillard reaction. However, as a competitive reaction, the isomerization of d-glucose was suppressed and required significantly higher Ea values in ultrasound-assisted Maillard reaction (100.8 ± 6.2 kJ mol-1) compared with that in thermal Maillard reaction (84.2 ± 5.7 kJ mol-1). These finding may be attributed to an extremely high temperature and pressure environment, despite of being only momentarily, generated by high-intensity ultrasound.