The fat globule membrane in ice cream

A method for determining the average thickness of the membrane around the fat globules in homogenised ice cream mix from the mix viscosity is examined. The difficulties with this approach, such as the non‐Newtonian behaviour of the mix, the polydisperse nature of the fat globule size distribution and the contribution of the micellar casein to the volume fraction of the aqueous phase, are discussed. Values of 60 to 90 nm for the effective “hydrodynamic” thickness have been obtained for ice cream mixes of 9% w/w vegetable fat and 10.5% w/w skim milk solids. It is suggested from these values, and from the interpretation of electron micrographs of similar mixes, that part of the micellar casein is attached to fat globules, thus increasing the effective volume fraction of the fat and accounting for the abnormally high viscosities of these mixes.