he firmness of ice cream is related to its structure. The air cells of ice cream structure are essentially spherical although there is some distortion due to fat and ice crystal formation (Prentice, 1992). The material surrounding these air cells is a non-Newtonian fluid containing clumps of fat (up to 80%) and small ice crystals. In fat reduced ice cream products, it is clear that the rheology of the composite fluid surrounding the air cells will be altered due to the reduction in the fat clumps which predominate the composite fluid of conventional ice cream structure.