High-intensity ultrasound production of Maillard reaction flavor compounds in a cysteine–xylose model system

• High intensity ultrasound processing was applied to a cysteine–xylose model system.
• Sonication of model system generated odor-active Maillard reaction products.
• Reaction products 2-methylthiophene and tetramethyl pyrazine were optimized.
• Sonication generated fewer sulfur-containing odor compounds than heating.
• Degassing effect of ultrasonic treatment must be considered in flavor generation.

Application of high intensity ultrasound has shown potential in the production of Maillard reaction odor-active flavor compounds in model systems. The impact of initial pH, sonication duration, and ultrasound intensity on the production of Maillard reaction products (MRPs) by ultrasound processing in a cysteine–xylose model system were evaluated using Response Surface Methodology (RSM) with a modified mathematical model. Generation of selected MRPs, 2-methylthiophene and tetramethyl pyrazine, was optimal at an initial pH of 6.00, accompanied with 78.1 min of processing at an ultrasound intensity of 19.8 W cm−2. However, identification of volatiles using gas chromatography–mass spectrometry (GC/MS) revealed that ultrasound-assisted Maillard reactions generated fewer sulfur-containing volatile flavor compounds as compared to conventional heat treatment of the model system. Likely reasons for this difference in flavor profile include the expulsion of H2S due to ultrasonic degassing and inefficient transmission of ultrasonic energy.