Spheroidal Fat Crystals: Structure Modification via Use of Emulsifiers

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Emulsifiers were used to modify the kinetics of formation and morphology of spheroidal fat crystal assemblies generated via the confined gap shear-cooling of model fat systems consisting of fully hydrogenated canola oil (FHCO), canola oil (CO), and glycerol monostearate (GMS), glycerol monopalmitate (GMP), sorbitan monostearate (SMS), or sorbitan tristearate (STS). The presence and morphology of spheroidal fat crystals were dependent on emulsifier type and concentration, with GMS, GMP, and SMS significantly reducing spheroid size at lower concentrations and causing deformation of the crystals into irregular and elongated shapes at higher concentrations. STS significantly hindered the formation of spheroidal crystals and instead promoted globular crystalline assemblies. Thermal analysis and X-ray diffraction revealed that samples crystallized primarily into the β′ polymorph along with a smaller amount of α polymorph. The ratio of α to β′ polymorphs generally increased with emulsifier concentration and imposition of higher laminar shear rates, suggesting the importance of two phenomena: (i) shear may influence the interactions between triacylglycerols at a molecular level, affecting the type of nanoplatelets formed and their interactions to form crystallites and subsequent crystals, and (ii) the extent of shear (rate/duration) may affect the rate and/or amount of emulsifier incorporated into triacylglycerol crystal lattices. Overall, these results demonstrated that fat crystal structures may be tailored with the combined use of emulsifiers and laminar shear.