Ultrasound-assisted Maillard reaction prepared whey protein isolate–arabinogalactan conjugates: Structural and functional properties

The proteins modified with polysaccharides through the glycation reaction are capable of improving the functional properties of proteins. This study investigated the improvement of structural and functional properties of whey protein isolate-arabinogalactan conjugates (UHWPI-AG) through ultrasound-assisted Maillard reaction. Ultrasound significantly enhanced the degree of conjugation compared with conventional wet-heating, as evidenced by Fourier-transform infrared (FTIR) spectral shifts in amide I and II bands. Fluorescence spectroscopy confirmed that both glycation and ultrasound treatment induced structural modifications in the whey protein isolate. Notably, the results of scanning electron microscopy indicated that UHWPI-AG had a denser and more porous honeycomb-like structure. Additionally, compared with the nature whey protein isolate (WPI), ultrasound-assisted glycation resulted in UHWPI-AG with a smaller mean particle size, higher surface charge, and reduced surface hydrophobicity and contact angle. These changes collectively improved the thermal stability, solubility, emulsifying property, foaming property, and antioxidant activity of the WPI. Moreover, emulsions prepared using UHWPI-AG as the emulsifier exhibited excellent storage stability. Therefore, ultrasound-assisted Maillard reaction may be a promising strategy for enhancing the functional properties of proteins.