In pressure-induced crystal growth of triolein from melt at pressures up to 300 MPa and at temperatures between 283.16 and 293.16 K, we can distinguish three different crystal morphologies. Raman spectroscopy indicates that they are related to different polymorphic structures. Switching from the most stable to a less-stable structure implies a jump in the growth rate to a maximum value. As pressure increases, the growth rate decreases indicating that the growth is transport limited. Measurements at different temperatures show that the growth rate is mainly governed by pressure. In a certain parameter range, we observe crossnucleation to crystals with a higher growth rate. These crystals have a Raman fingerprint not yet described in the literature.

High-pressure treatment is a promising option for improving mechanical properties and processing parameters of fat-containing products. To identify optimum processing windows, melting curves, crystallization kinetics, and pathways for transferring the optimized structures to atmospheric pressure need to be known. Here, we provide melting curves of different polymorphic forms of triolein in the industrially relevant pressure range. The melting points of different polymorphic forms are detected optically in thin samples during stepwise changes of pressure or temperature. For cross-nucleated spherulites, this method allows determining the respective melting points of nuclei and overgrown structures. Tracing the melting curves to atmospheric pressure confirms previous identification of the polymorphic forms at high pressure and enables identifying a previously reported but undefined structure as the β 2-form. Employing Raman spectroscopy, it is confirmed that the polymorph remained unaltered during the pressure release. With increasing pressure, the melting curves of the different polymorphic forms approach each other until they successively merge at the highest pressure levels studied.