Tripalmitin-driven phase segregation in multicomponent fats

This contribution reviews the recrystallization of high-melting components in PO (PO)-based fat blends monitored by differential scanning calorimetry (DSC) and time- and temperature-resolved small- and wide-angle X-ray scattering (SAXS/WAXS) in four different case studies. Different temperature-time profiles, including annealing, were applied to investigate the crystallization kinetics with focus on mixed crystal formation (co-crystallization) and its potential for being controlled. The main focus was hereby to capture phase segregation events during melting. These segregation effects are caused by true recrystallization from either the melt or melt-mediated polymorphic transition of the tripalmitin (PPP)-rich high-melting fraction. The first case study illustrates the formation of mixed crystals by step-wise crystallization and evaluation of the subsequent melting DSC curve. By applying low heating rates, the evolution of the observed melting points combined with information on lamellar spacings revealed a time-dependent formation of the medium-melting fraction. The second case study discusses the effects and interplay of heating rate, crystallization temperature, and partial melting on the phase segregation in PO crystallization. The third case study focuses on PPP as driver for phase segregation in a palm-based commercial hardstock (PCM). Fourth, the same PCM was subjected to different crystallization routines including annealing to modify the mixed crystals formed. Deduced from SAXS/WAXS observations, annealing during the cooling step proved greatly aiding the formation of a mixed crystal, which would withstand phase segregation of PPP during the melting.