Q. Describe the foaming properties?

Foods like meringue, ice cream and beer contain foams. A number of foods possess good foaming properties on account of the proteins they contain that can provide the stability to products and impart characteristic qualities to foods. Surface proteins are stretchy and flexible almost like a loose rubber sheet, which provide resistance to disruptive shear forces and compression/dilatation forces. This is obtained by denaturation/unfolding of polypeptide chains and exposing substantial regions of hydrophobic residues into air or lipid phases where they are stable. The ability of the protein films to resist shearing and high level stretching capability contributes to good foaming and emulsifying properties. These properties are provided from extensive interactions between protein molecules and reach a maximum at the isoelectric point of the protein where electrostatic repulsion is at a minimum.