INFORM February 2025 Volume 36 (2)

OLEOGELS

inform February 2025, Vol. 36 (2) • 15

Tiago C. Pinto at the XRD1 beamline at Elettra Sincrotrone Trieste. Source: Tiago C. Pinto, University of Helsinki

emulsions in the digestive system. Pinto’s research focuses on correlating variations in the microstructures of these materi als with their macroscopic properties and implications in the body. Due to the low concentration of crystals within oleogel samples—especially when diluted in a digestion titrate—con ventional X-ray diffraction (XRD) methods are not capable of distinguishing changes in characteristic structures during digestion. For this reason, the researchers brought their experiments to Elettra Sincrotrone Trieste, a synchrotron light source in Basovizza, Italy. The team took advantage of the superior pho ton flux provided by the XRD1 beamline at Elettra to analyze emulsions with a variety of compositions as they underwent in-vitro digestion. “The signal-to-noise ratio with benchtop XRD would have been too low,” Pinto said. “With synchrotron XRD, we were able to identify even subtle variations in crystal structure during the digestion process.” In fact, the use of synchrotron light allowed for the anal ysis of emulsions even when only a small fraction of lipid crys tals—in some cases as low as 0.3 mg/mL—diffracted radiation. INVESTIGATING A VARIETY OF OIL PHASES AND EMULSIFIERS The researchers studied emulsions with a structured oil phase in a dispersed water phase. Some samples contained oil drop

lets with just solid lipids, and some contained a blend of solid and liquid lipids. The structure of water is well-characterized, whereas the intricate, polymorphic crystal structures of oleogels during digestion are less understood. Having the oil phase suspended in water, rather than the other way around, offered an experi mental advantage, since the samples were overall more homo geneous, and therefore easier to analyze at the synchrotron. In total, the team analyzed 16 combinations of oil phases and emulsifiers (see page 16). The oil phases included combi nations of different concentrations of rapeseed oil, candelilla wax, sunflower wax and fully hydrogenated palm oil (FHPO). Emulsifiers included modified starch, Tween 20 (a common surfactant used in food applications), whey protein isolate and hydroxypropyl methylcellulose (a cellulose derivative). The researchers chose these particular emulsifiers to test examples of macronutrients, indigestible fibers and polymers as struc turing agents. “We wanted to look into whether structural changes during digestion depend more on the composition of the oil in the sample or the emulsifier,” Pinto said. “We were also look ing at factors such as the size and shape of lipid crystals, layer stacking and polymorphic form to see whether they affected the digestibility and digestion rate of the emulsions.” After months of preliminary experiments at the University of Helsinki, the researchers conducted their 48-hour experi ment at the synchrotron. This was challenging work, as each