Heterogeneous Nucleation of 1,3-Distearoyl-2-oleoylglycerol on Tristearin Surfaces

The following work investigates the heterogeneous nucleation of 2-oleodistearin (SOS) triglycerides on surfaces formed by crystals of tristearin triglyceride (SSS). This work shows, through computer simulations and nucleation kinetics, that SOS may heterogeneously nucleate on SSS surfaces. Atomic-scale molecular dynamics showed that SOS molecules exhibited an affinity to a simulated SSS surface. Nucleation kinetics using differential scanning calorimetry showed that the inclusion of minor amounts of SSS (from 1 to 4%) in an SOS melt resulted in an increase in the isothermal nucleation rate of crystallizing SOS. Using a model based on the Fisher-Turnbull approach, estimates of the surface free energy, activation free energy, and the critical radius were calculated from the nucleation rates. The estimated parameters demonstrate the heterogeneous nucleation of SOS on SSS surfaces: reduced surface free energies, activation free energies, and critical radii with the inclusion of SSS in an SOS melt. This may point to strategies to enhance the nucleation of one of the three major triglycerides present in cocoa butter and the one that crystallizes first from the melt for better control of the chocolate tempering process.