The experimental setup of this study was based on the measure- ent of the liquid solid transitions of the lipid carrier both in bulk and in emulsions. As shown in Figure 3, crystallization of bulk and dispersed HPKO occurred at different temperature Tc onset 24 °C and c (endset) 9 °C for bulk HPKO and T (onset) T eC in emulsified HPKO. This difference w and T thoroughly discussed by Cornacchia and Roos (2011b, 2011c) and was attributed to the different mechanism by which bulk lipid and finely emulsified lipid droplets crystallized. and to the effect of the protein emulsifier. Crystallization consists of 2 steps: nucleation (or initiation) and crystal growth (or propagation). Nucleation is formation of ordered molecular d nuclei, which act solid templates to form embryos that can grow to crystals. In O/W emulsions, nucleation and growth in the lipid phase are relatively slow processes and both contribute to regulation of crys tallization kinetics (Reid 1998). Crystallization of bulk lipids often follows a heterogeneous nucleation pathway which is catalyzed by impurities (foreign bodies that provide a surface for nucleation and crystal growth. Conversely, finely dispersed emulsified lipids are claimed to show homogeneous nucleation requiring molecular assembly of lipid molecules to form nuclei by themselves with out catalyzing impurities and surfaces (Simoneau and others 1993; Awad and Sato 2002; Coupland 2002: Palanuwech and Coupland 2003: McClements 2005). We also expect that crystallization of lipids in small dispersed particles is delayed by molecular inter- actions with surface active components, that is, surfactants and proteins (Cornacchia and Roos 2011 b, 2011 c). Crystallization requires a temperature substantially below the Trn to establish a sufficient thermodynamic driving force for nu- cleation (Gliquid Gold favors crystallization), but an activation for the formation of nuclei exceeding energy barrier (kinetic factor) the minimum size required for crystal growth must be overcome. Thus, nucleation can only occur well below Tm (supercooled sys tem). The degree of supercooling is lower in heterogeneous nu cleation than in homogeneous nucleation as the catalytic surfaces reduce the number of molecules required form the lipid to embryos (Reid 1998; 2002). systems, where in this phase is composed of different triglycerides (TAGs) as is HPKO), crystallization can occur as a binary mixture case low-melting (Murray and of high-melt TAGs and composition-dependent 1996; Rousseau 2002) with a melting profile. Our findings also supported the theory of reduced nucleation because of kinetic factors slowing down mass transfer and molecular reorganization toward nucleation sites within dis ed lipid particles due to hydrophobic interactions between lipid molecules and protein emulsifiers. This resulted in a hig degree of supercooling required for the nucleation of the emul sified lipid molecules compared to bulk lipid irrespective of the nucleation mechanisms