Precipitation/Solubility of Proteins
Most of the functional properties are dependent on the degree to which the proteins are soluble. The solubility behaviour provides a good index of potential application of proteins. This is so because the degree of insolubility is probably the most practical measure of protein denaturation and aggregation and because proteins that initially exist in a denatured, partially aggregated state, often have an impaired ability to participate effectively in gelation, emulsification and foaming.
Note, in general, proteins, which are highly soluble, may be used in applications where emulsification, whipping and film formation are important whereas low solubility may be desired in applications with high protein levels and when limited emulsification or protein-protein interactions are needed.
Solubility of proteins is markedly and irreversibly reduced when heating is involved. However, heat treatments may be unavoidable to achieve other objectives (microbial inactivation, removal of off-flavor, removal of water and others).