Isostatic Ultra-High-Pressure Effects on Supercooled Melts in Colloidal Triglyceride Dispersions

Abstract

Colloidal triglyceride dispersions can form metastable supercooled melts that need tedious tempering processes to be transformed into a crystalline state. We investigated the possibility of transforming the supercooled melts into crystals in a short time by treatment with isostatic high pressure. Nanosized supercooled melts of triglycerides in aqueous dispersions (prepared by high-pressure homogenization) were exposed to isostatic ultrahigh pressure for short periods to initialize crystallization processes. The dispersions were analyzed with different appropriate measuring methods such as differential scanning calorimetry, nuclear magnetic resonance, X-ray scattering, and electron paramagnetic resonance. The resulting particle sizes were estimated by photon correlation spectroscopy and transmission electron microscopy. The results of differential scanning calorimetry, X-ray, and nuclear magnetic resonance experiments show the induction of triglyceride particle crystallization by high-pressure treatment. Electron paramagnetic resonance spectroscopy shows that the triglyceride crystallization coincides with relocation of the lipophilic probe into a more polar environment. Transmission electron microscopy micrographs show the transformation of supercooled liquid particles into crystallized anisotropic particles. Crystal transformation in nanoscaled systems can be delayed for months, depending on the materials and the composite. It is shown that isostatic high-pressure treatment can be a valuable method to induce, accelerate, and control crystallization processes in specific colloidal triglyceride dispersions.