The composition of whey protein fractions that change. depending on the processing methods are reported to influence the functionality of WPI. The WPI prepared by ion exchange technique that was used in our study, normally. contains the full complement of β-lactoglobulin, but much. of the -lactalbumin and some of the immunoglobulins and. other protein components are lost. The principal functional- ity of -lactoglobulin is gelation and thickening.The -lac- toglobulin fraction is particularly important in forming. large protein networks after heating [ 22]. In the study of Britten [ 23 ], WPI was dispersed in water (8%), pH was. adjusted and ionic calcium was added. The dispersion was heated at 95 ° C for 15 min and then cooled to room temper-. ature. Electron micrographs showed that the increse viscos-. ity of protein dispersions after heating reXects the. formation of linear polymers. Calcium is beleived to pro- mote protein association and increase polymer length. Extremely high viscosity in ice cream mixes containing. WPI can be sourced from these polymers or large protein. networks and also from higher molecular weight of WPI in. comparison to inulin.