Related Experiment Video
Updated: Nov 8, 2025

Solubility of Hydrophobic Compounds in Aqueous Solution Using Combinations of Self-assembling Peptide and Amino Acid
Published on: September 20, 2017
Characterization of interactions between whey protein isolate and hyaluronic acid in aqueous solution: Effects of pH
Weigang Zhong1, Changqing Li1, Mengxue Diao1
1Department of Food Science, College of Food Science and Engineering, Jilin University, Changchun, Jilin, 130062, China.
Abstract:
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 pHΦ1 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 (pHΦ2). WPI/HA mixtures showed shear thinning behavior and elastic property. Whey protein underwent significant α-helix structure change when interacting with HA in range of pHΦ1>pH > pHΦ2 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.
Related Concept Videos
Mixtures of Acids
A Mixture of a Strong Acid and a Weak Acid
In a mixture of a strong acid and a weak acid, the strong acid dissociates completely and becomes a source of almost all the hydronium ions...
Mixtures of Acids
In a strong and weak acid mixture, the strong acid dissociates completely and becomes a source of almost all the hydronium ions present in the solution. In contrast, the weak acid shows...
Polyprotic Acids
Factors Affecting Solubility
Titration Calculations: Strong Acid - Strong Base
A titration is carried out for 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M of a strong base NaOH. The pH at different volumes of added base solution can be calculated as follows:
(a) Titrant volume = 0 mL. The solution pH is due to the acid ionization of HCl. Because this is a strong acid, the ionization is complete and the hydronium ion molarity is 0.100 M. The pH of the solution is then:
pH Scale

