Nucleation behaviour of tripalmitin from a triolein solution

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Abstract
Nucleation of tripalmitin (PPP) crystals from melt and from its binary triolein (OOO) solutions was studied by differential scanning calorimetry (DSC) and optical microscopy. Cooling DSC thermograms for either pure PPP or OOO exhibits a single exotherm. For the solutions, two widely separated peaks due to PPP and OOO were observed. The PPP peak is broadened and shifts down to a lower temperature as the OOO content in the solution increases. A modified Turnbull and Fisher equation was used for nucleation data analysis. The temperature for maximum supercooling of the solution is reduced by OOO but the degree of maximum supercooling remains unchanged at 22oK. An interfacial free energy of 9.45 erg/cm2 for β‐PPP/ melt was deduced. This value drops rapidly to a slightly lower value of 8.95 erg/cm2, in triolein solution. The effect of a reduced interfacial free energy on nucleation is critically discussed in the light of a simultaneous reduction in the melting point of β‐PPP in the solution.