Characterization of interactions between whey protein isolate and hyaluronic acid in aqueous solution: Effects of pH and mixing ratio

Interactions between whey protein isolate (WPI) and hyaluronic acid (HA) were characterized as functions of pH (6.0-1.0) and protein to polysaccharide ratio (R, 1:4-10:1). Intramolecular soluble complexes formed at pHc of 5.6-5.8, followed by intermolecular insoluble complexes formed at pH phi 1 of 4.4-4.6. Complexes at ratios below 4:1 reached maximum optical value at pH 2.4 while samples above 4:1 peaked at pH 3-3.4 then precipitated. WPI/HA coacervates completely dissociated into soluble complex at pH 1.6-1.8 (pH phi 2). WPI/HA mixtures showed shear thinning behavior and elastic property. Whey protein underwent significant alpha-helix structure change when interacting with HA in range of pH phi 1>pH > pH phi 2 and at low R values (1:4 and 1:2). Scanning electronic microscope (SEM) pictures showed pH and mixing ratio dependent microstructural changes corresponding with phase transition. Data may provide helpful information for further application of WPI/HA complexes in medical, food and cosmetic fields.

Automated summary

The study investigated the interactions between whey protein isolate (WPI) and hyaluronic acid (HA), revealing the formation of different complexes with distinct properties and structural changes at varying pH values and protein to polysaccharide ratios, potentially useful for applications in the medical, food, and cosmetic fields.