Unveiling the fate of structured oils in engineered emulsions during in vitro digestion

Lipid overconsumption can lead to hyperlipidaemia and obesity, which poses an increased risk for cardiovascular diseases, metabolic syndrome, and type 2 diabetes. With billions of adults and millions of children affected, the economic burden exceeds 250 billion euros annually in healthcare costs. A strategic approach to combat obesity involves regulating lipid digestion using engineered emulsions. By engineering the droplets’ lipid core and interface, it is possible to modulate their digestive fate, creating partially indigestible emulsions that reduce caloric intake while ensuring the delivery of essential fatty acids crucial for human health. Motivated by the need to understand lipid crystal evolution inside the engineered lipid core during simulated digestion, our research sheds light on the intricacies of this process. This knowledge is crucial for designing emulsions with tailored lipid digestion, offering potential solutions to the escalating global obesity crisis.
The present work entails the in vitro digestion of 16 emulsions, tracking the evolution of the lipid droplets structured with lipid crystals, by means of synchrotron X-ray diffraction. This systematic study aims to unveil modifications in lipid crystal structure during digestion. The use of synchrotron light allowed for the analysis of digested emulsions where only a small fraction of lipid crystals, in some cases as low as 0.3 mg/mL, is able to diffract radiation. A total of 96 diffractograms were collected and correlated with oil lipolysis kinetics, droplet characteristics, microscopy observations, and melting profiles. In general, we could observe a rearrangement of lipid crystals at the nanoscale during simulated digestions, including polymorphic transformations and lamellar shrinkage along with the formation of other structures possibly originating from lipid digestion products. This research unlocks novel methods to modulate lipid digestibility, potentially offering concrete solutions and preventive measures against obesity and its associated diseases.