Tracking the phase transition process of solid fats and fatty oils by time-split X-ray diffraction measurements

There are many crystal polymorphs in the solid fats and fatty oils that are used as raw materials in foods such as chocolate and margarine. Fat or fatty oil is cooled down to solidify it from a high temperature to precipitate a crystal. The crystals that form in this precipitate differ depending on the cooling speed; therefore, control of rate of temperature change and the holding temperature are important factors to determine the property of the crystal.

Previously, to track the state variation (phase transition) over a short time period, a high-intensity radiation source was required; however, by using the NANO-Viewer small angle X-ray scattering instrument and a high-sensitivity/high-resolution 2D X-ray detector, a high speed time-split measurement every few seconds becomes possible even in the laboratory.

control of rate of temperature change and the holding temperature are important factors

Figure 1: 2D image

The phase transition behavior of the triacylglycerol tripalmitin during a temperature increase of 5°C/min was confirmed every five seconds by simultaneous X-ray measurement with DSC (FP82: METTLER TOLEDO). When the diffraction profiles (2) to (5) in Fig. 3, and (1) and (4) in Fig. 1 corresponding to the 47°C endothermic peak are compared, it is clearly observed that the 4 to 5 Å short-range order (corresponding to the outside ring of Fig. 1, changes first, before the approximately 50 Å long-range order (corresponding to the inside ring of (1) and (4) in Fig. 1 changes. Furthermore, the beta phase peak becomes apparent together with the exothermic peak (6) in Fig. 1 and Fig. 3.

phase transition behavior was confirmed
phase transition behavior was confirmed
Figure 2: DSC curve
Figure 3: Combined 2θ

The S-MAX3000 pinhole SAXS camera design is available with a choice of conventional or high brilliance X-ray sources. A 3-meter, fully evacuated camera length provides both high intensity and high resolution. Coupled with a fully integrated 2-dimensional multi-wire proportional counter, the system is capable of making highly sensitive measurements from both isotropic and anisotropic materials. A wide range of sample stage attachments provide maximum flexibility in controlling environmental sample conditions during measurement. Read more...