Résumé :
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The proteins in mill have a range of physical functional properties, such as solubility, heat stability, gelation, viscosity, emulsification and foaming, that govern the application of milk and milk products in foods. The process of fat destabilisation establishes one of the major structural elements in ice-cream, along with ice crystallisation, air bubble formation, and macromolecular structure within the unfrozen phase. Proteins adsorb to emulsified fat after homogenisation to create a fat interface. Adsorbed protein levels after ageing are inversely proportional to the presence of added surfactants. Increasing levels of protein adsorption impedes fat destabilisation during freezing by enhancing steric stabilisation of the fat globule. Thus, fat: protein interactions ultimately control ice-cream structure. We have 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 air interfaces. We have also demonstrated that fat destabilisation can be enhanced in the absence of added surfactant by controlling protein adsorption through manipulation of the homogenisation process.
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