Effect of ultrasound treatment on the wet heating Maillard reaction between mung bean [Vigna radiate (L.)] protein isolates and glucose and on structural and physico-chemical properties of conjugates

BACKGROUND: The objective of this study was to determine the effect of ultrasound treatment on the wet heating Maillard reaction between mung bean protein isolates (MBPIs) and glucose, and on structural and physico-chemical properties of the conjugates. RESULTS: The degree of glycosylation of MBPI-glucose conjugates treated by ultrasound treatment and wet heating (MBPI-GUH) was higher than that of MBPI-glucose conjugates only treated by wet heating (MBPI-GH). Solubility, emulsification activity, emulsification stability and surface hydrophobicity of MBPI-GUH were higher than that of MBPI-GH. Grafted MBPIs had a lower content of alpha-helix and unordered coil, but a higher content of beta-sheet and beta-turn structure than MBPIs. No significant structural changes were observed in beta-turn and random coil structure of MBPI-GUH, while alpha-helix content increased with ultrasonic time, and decreased at 300 W ultrasonic power with the increase of beta-sheet. MBPI-GUH had a less compact tertiary structure compared to MBPI-GH and MBPI. Grafting MBPIs with glucose formed conjugates of higher molecular weight, while no significant changes were observed in electrophoresis profiles of MBPI-GUH. CONCLUSION: Ultrasound-assisted wet heating Maillard reaction between MBPIs and glucose could be a promising way to improve functional properties of MBPIs. (C) 2015 Society of Chemical Industry