Solidification and phase transformation behaviour of food fats — a review

Recent studies on physical behaviour of food fats have been reviewed. with an emphasis on solidification properties in bulk and emulsion states. It was shown that the use of synchrotron radiation X-ray beam highlighted the solidification behaviour of polymorphic fats, which was not unveiled by traditional X-ray beams on a laboratory scale as summarised in the following: (a) kinetic processes of molecular ordering of lamella-structured fat crystals. (b) mixing behaviour of different triacylglycerols forming miscible, eutectic, and molecular compound crystals, and (c) remarkable influences of shearing forces on the rapid solidification of the more stable forms of cocoa butter. These results have given some indications to the physical control of fat solidification. and the blending and fractionation of solid fats. The influences of hydrophobic emulsifiers on the solidification of fat crystals in O/W emulsions, which were in-situ monitored by an ultrasound velocity technique, have shown that the addition of highly hydrophobic emulsifiers having long-saturated acid moieties accelerated the nucleation of the fats at the interface areas of the emulsions. These effects are also indicative for the selection of the emulsifier for the control of the fat solidification in the emulsion phases.