Unveiling the fate of lipid crystalline structures in engineered emulsions during in vitro digestion

This study investigates how lipid crystalline structures in emulsions evolve during digestion, aiming to inform functional food design and potentially modulate lipid digestion. Using synchrotron-based X-ray diffraction, we monitored real-time structural transformations of lipids during in vitro digestion of 16 emulsions with varied lipid phases and emulsifiers, revealing rapid, composition-dependent transformations. These changes include lamellar packing changes and the emergence of different polymorphic forms originating from digestion products, as early as the first two minutes of lipolysis. Palm-based systems showed a reduction in native β-polymorphs, while wax-based systems retained β'-forms. Lamellar packing spacings shifted towards 62 Å and 48 Å across all systems, suggesting similar structural adaptation, regardless of the original sample composition. Modified starch and hydroxypropyl methylcellulose as emulsifiers reduced the extent of lipolysis. These findings offer insight into lipid self-assembly during digestion and support the development of functional foods targeting metabolic health.