Impact of different ultrasonication strategies on the structural, rheological, and functional properties of mung bean protein isolate-gum arabic conjugates formed via the Maillard reaction.

BACKGROUND

The impact of different ultrasound (US) strategies on the formation of mung bean protein isolate-gum arabic (MBPI-GA) conjugates formed by the Maillard reaction was investigated to overcome the techno-functional limitations of native mung bean protein isolate (MBPI). Two primary sonication strategies - pre-sonication of protein (P100, P200) and co-sonication of the protein-polysaccharide mixture (PG100, PG200) - were compared with traditional wet-heating controls.

RESULTS

High-intensity ultrasound (200 W) significantly accelerated Maillard reaction kinetics, resulting in the highest degrees of grafting (44% to 47%) compared with wet-heated MBPI-GA conjugates without ultrasound treatment. Fourier transform infrared (FTIR) spectroscopy and reactive sulfhydryl group analyses confirmed that ultrasonic cavitation induced structural unfolding, as evidenced by a significant reduction in β -sheet fractions and a concomitant increase in random coil content, exposing buried reactive sites. All sonicated conjugates exhibited more than a twofold increase in protein solubility compared with the native protein. The PG200 strategy maximized emulsifying activity index (EAI) and water-holding capacity (8.5 g g-1), and PG100 yielded the highest in vitro protein digestibility (approximately 60%) and improved thermal stability. The denaturation temperature ( T d ) increased from 81.32 °C (native MBPI) to 82.65-83.63 °C in the co-sonicated conjugates, accompanied by a pronounced reduction in denaturation enthalpy ( Δ H ) from 15.7 to 5.5 J g-1. Rheological assessments revealed that the conjugates formed a heat-stable, liquid-like network in which the loss modulus ( G ″ ) consistently exceeded the storage modulus ( G ' ), thereby preventing thermal gelation and precipitation during processing.

CONCLUSION

These findings suggest that co-sonication of MBPI-GA mixtures is a highly effective green modification strategy for producing homogeneous, functional, and highly digestible plant-based biomacromolecules. The resulting conjugates show considerable potential for use in liquid food formulations and high-temperature industrial processes. © 2026 Society of Chemical Industry.