Define Protein Stabilized Food Emulsions?
Many food products are emulsions (eg. milk cream, ice creams, cream, butter etc.) and protein constituents often play a major role in the stabilization of these colloidal systems. In the fresh milk, soluble proteins are immunoglobulins. Homogenization of milk increases emulsion stability because it reduces the size of fat globules and because newly formed casein submicelles displace the immunoglobulins and adsorb to fat globules. The proteins stabilize emulsions and contribute physical and rheological properties, like thickness, viscosity, elasticity and rigidity that determine resistance to droplet coalescence. Ionization of amino acid side chains may also take place depending on the pH and this provides electrostatic repulsive force that favors emulsion stability. This functional property is important in the formation of many common food products, such as salad dressings and sausages. Proteins can bind to water, lipids, volatile flavours and other substances and possess important functional properties.