Controlling ice-cream structure by examining fat: protein interactions

The proteins in mill have a range of physical functional properties, such a s solubility, heat stability, gelation, viscosity, emulsification and foami ng, that govern the application of milk and milk products in foods. The pro cess of fat destabilisation establishes one of the major structural element s in ice-cream, along with ice crystallisation, air bubble formation, and m acromolecular structure within the unfrozen phase. Proteins adsorb to emuls ified fat after homogenisation to create a fat interface. Adsorbed protein levels after ageing are inversely proportional to the presence of added sur factants. Increasing levels of protein adsorption impedes fat destabilisati on during freezing by enhancing steric stabilisation of the fat globule. Th us, fat: protein interactions ultimately control ice-cream structure. We ha ve examined the fat structuring phenomena by microscopy techniques and have shown that optimal fat destabilisation is comprised of partial coalescence of fat within the serum phase and enhanced adsorption of fat globules to a ir interfaces. We have also demonstrated that fat destabilisation can be en hanced in the absence of added surfactant by controlling protein adsorption through manipulation of the homogenisation process.