Correlation between viscosity and solubility

Viscosity and consistency of protein systems are the important functional properties in fluid foods, such as  beverages, soups, sauces and creams. Correlation between viscosity and solubility is not  simple. Insoluble heat denatured protein powders do not develop high viscosity when placed in aqueous medium. Highly soluble protein powders with low water absorption and swelling capacities (whey proteins) also exhibit low viscosity at neutral or IpH. Soluble protein powders with high initial water absorption capacities (sodium caseinates and some soy protein preparations) develop a high viscosity. Thus, for many proteins, a positive correlation is observed between water absorption and viscosity.