The structure of many food products is based on networks of crystalline particles. In oil-continuous products, such as margarine or butter, this network consists of a mixture of small crystallites of triglycerides (also known as triacylglycerols or TAGs) . Product quality is related to the manufacturing process used, since the growth of the fat crystals can be tuned by TAG composition and cooling rates. For a given composition, fat network formation depends on the amount of TAG crystals and their dimensions and is therefore directly related to the surface to volume ratio.
Small Angle X-ray Scattering (SAXS) measurements were performed on both home-lab equipment (D8-Discover, Bruker-AXS) and at the ID02 beamline at the ESRF, Grenoble to obtain information about the thickness of the fat crystallites (domains). Based on the Full Width at Half Maximum (FWHM) of the first order diffraction line the average crystallite thickness is calculated using the Scherrer equation. However, in order to have a better understanding of the structuring capability of the TAGs, knowledge of the thickness distribution of the crystallites is preferred.
Peak shape analysis based on Fourier transformation methods was performed on the X-ray diffraction patterns. We considered the Bertaut-Warren-Averbach  method to be a feasible approach to resolve crystallite thickness distributions (CTD) in TAGs where molecules are packed in repeating bi-layers in longitudinal direction. This method, initially developed for metals, was also successfully applied to obtain distributions of domain thickness of layered clay minerals . The proof of principle of BWA method for CTD in fats is presented on a model system consisting of mono-acid TAG (tripalmitate) subject to shock- and slow-cooling. Examples on real-use mixed-acid TAG systems or so-called fat blends are presented as well.
With additional knowledge of the thickness distribution of triglyceride crystallites it might be possible to tune the fat blend composition and to further optimize the processing of food products.