Emulsions under shear - the formation and properties of partially coalesced lipid structures

Partial coalescence in semi-crystalline emulsion droplets is essential to the manufacture and quality of many dairy products including ice cream, whipped cream, and butter. In real food emulsions this process occurs under fluctuating temperatures and shear rates and some of the effects of these factors are considered in this work. Two approaches to the problem are reported. In the first, the freeze-thaw stability and shear modulus of a food oil emulsion during a freeze-thaw cycle is related to the volume fraction of dispersed phase. In the second approach the rate of crystallization of emulsified n-hexadecane in the presence of solid n-hexadecane is shown to be independent of applied shear rate. Some ideas on how these approaches may be combined for a fuller understanding of the partial coalescence process are presented. (C) 2001 Elsevier Science Ltd. All rights reserved.