The impact of ultrasound synergized with salt on the structure and loading characteristics of whey protein isolate-chitosan complexes.

This study examined the impact of ultrasound synergized with salt on the structure and loading properties of whey protein isolate (WPI)-chitosan (CS) complexes. A higher curcumin loading value was obtained when WPI and CS were combined at a 10:6 mass ratio with a complex concentration of 8 g/L. The synergistic effect of ultrasound combined with salt treatment directly applied to WPI was more effective in enhancing the loading capacity of curcumin than when applied to WPI/CS complexes. Different NaCl concentrations affected the structure of WPI and its complexing ability with CS differently. High NaCl concentrations could cause aggregation of WPI and its complexes. After ultrasonic treatment with 0.4 % NaCl, the particle size of WPI decreased from 330.4 to 213.3 nm, its hydrophobicity increased, and the α-helix structure unfolded. The complexes formed by modified WPI and CS had higher viscosity and a looser structure, enhancing curcumin loading capacity to 36.3 mg/g, an improvement of 25.8 % over the control. The curcumin encapsulated in the modified WPI/CS complexes showed greater radical scavenging activity compared to free curcumin. The results of this study offer valuable insights in the design and preparation of WPI/CS complexes with good loading capacity.