Assessment of rheological methods to study crystallization of palm oil fractions.

This study provides an evaluation of the use of rheology to characterize soft, semi-hard, and hard fats in relation to determine the crystallization onset, crystallization behavior, as well as microstructure development using either a plate-plate or a starch pasting cell (SPC). The results from this study demonstrate that when applying rheology to study fat crystallization, the results must be interpreted with care. The application of a plate-plate geometry allowed for sensitive evaluation of the initial nucleation phase, which was not possible with an SPC. Both geometries could provide information on crystallization behavior in terms of one-step or two-step crystallization. However, in the late stage of the crystallization process, when the fat crystals form a strong network, the SPC could not describe differences in the rheology of the fat-crystal network, which was a possibility by the use of a plate-plate geometry. Thus, oscillatory rheology with a suitable geometry can be used to evaluate the entire crystallization process.