Interactions and Phase Behaviors between Whey Protein Isolate and Fucoidan: Effects Of Protein/Polysaccharide Mixing Ratio and Ph

This study investigated the interaction mechanism of whey protein isolate (WPI) with fucoidan (Fuc) at various pH levels (2.0–7.0) and protein/polysaccharide mixing ratios (R = 1:1, 4:1, 8:1, 12:1, and 16:1). The results showed that complex formation was primarily determined by electrostatic interactions. The complexes exhibited higher stability when R = 4:1 and formed soluble and insoluble complexes under different pH conditions. Increasing the protein/polysaccharide mixing ratio contributed to the formation of complexes, and the interaction between the protein and polysaccharide was saturated when R = 12:1. Hydrogen bonding and electrostatic interactions existed between the WPI–Fuc complexes and resulted in favorable entropy generation, which facilitated the spontaneous binding of the exothermic reaction between WPI and Fuc. These findings provide valuable information regarding the application of WPI–Fuc complexes in the food industry.