Effects of high-intensity ultrasound on Maillard reaction in a model system of d-xylose and l-lysine

This study compared the effects of high-intensity ultrasound on Maillard reaction (MR) with those of thermally produced MR using a model system of d-xylose and l-lysine. The ultrasonic MR process had higher depletion rates of reactants and higher generation rates of intermediate MR products (MRPs) and melanoidins under relatively low processing temperatures (55 and 60 °C). However, the rates were lower for ultrasonic MR than thermal MR when the processing temperature increased to 65, 70 and 75 °C. Overall, ultrasonic MR had relatively low activation energy (Ea) compared to thermal MR (e.g. 55.59 vs. 80.42 kJ mol−1 for d-xylose depletion). Moreover, ultrasonic MR could produce at least one N-containing pyrazine (3-ethyl-2,5-dimethylpyrazine), one N-containing amine (butyl amine) and one O-containing volatile compound (maltol) that were absent from thermal MR. The difference in flavour generation might be a result of the extremely high, albeit momentary, temperature and pressure condition produced by high-intensity ultrasound.