Multi-scale triglyceride crystal network analysis using a benchtop ultra-small-angle X-ray scattering instrument

Abstract

Benchtop ultra-small-angle X-ray scattering (USAXS) offers a practical route to probing micron-scale structural features in soft-matter systems, provided that instrumental limitations are explicitly defined and respected. In this work, a Rigaku NANOPIX mini USAXS instrument is used to characterize hierarchical fat crystal networks, with emphasis on establishing a reliable analysis window and appropriate treatment of slit-geometry effects. Analyzer crystal rocking curves are employed to define a lower bound for quantitative analysis (q_min ≈ 3.4 × 10⁻⁴ Å⁻¹), while counting-statistics considerations define an upper bound (q_max ≈ 1.4 × 10⁻² Å⁻¹). Data outside this window are shown to be strongly influenced by direct-beam and noise artifacts and are therefore excluded from interpretation. Within the valid q-range, slit-smearing effects inherent to Bonse–Hart geometries are addressed by smearing structural models using open-source SASView software rather than numerically desmearing experimental data. Using cocoa butter, commercial chocolate, and a reference triglyceride mixture as representative case studies, power-law scattering regimes are extracted and compared with synchrotron SAXS measurements over overlapping q-ranges. While absolute slope values vary between instruments and samples, benchtop USAXS captures consistent scattering trends, including stable power-law behavior in tempered systems and transient curvature in untempered samples that diminishes upon storage. These results demonstrate that benchtop USAXS, when interpreted within a rigorously defined q-window and with appropriate resolution treatment, provides a reproducible and accessible tool for comparative analysis of hierarchical fat systems. More broadly, this study outlines best practices and interpretive boundaries for laboratory-scale USAXS measurements in soft-matter research.