Development of highly stable phytosterol oleogel particle-based emulsions with improved bioaccessibility of ꞵ-carotene

Oral administration is the most preferred route for drug and bioactive delivery, although it raises great challenges due to the involvement of the gastro-intestine system and limited bioavailability. In this research, gelled oil particle-based emulsion was formulated using ꞵ-sitosterol and γ-oryzanol (SO) mixtures, as structuring agents, to improve the β-carotene bioaccessibility.

The effect of SO concentration was analyzed under simulated GI conditions and changes in their particle size, zeta potential, and morphology was assessed. Furthermore, these differences were examined with respect to the oleogel particle susceptibility to gastrointestinal digestion and β-carotene bioaccessibility kinetics.GI digestion tests revealed that unstructured oil particles-based emulsions incubation in the stomach phase promotes particle aggregation and consequently leads to particle size increase in comparison to the structured oil particles-based emulsion. In the small intestine phase, the extent of lipid digestion was correlated to the particle size and the oleogel-network mechanical strength. More specifically, higher SO concentration led to stronger network that hindered lipolysis process, on one hand, while on the other hand, higher SO concentration also led to particle size decrease resulting in higher total extent of lipolysis. It was shown that smaller mixed micelles are formed during the lipolysis process when particles were prepared using higher SO concentration, implying on the ability to control micelle size during digestion. Moreover, the β-carotene bioaccessibility kinetics was directly related to the original particle size and density of the lipid phase that was controlled by the SO concentration. Overall, the results suggest that the combination of solid texture and liquid lipid core found in oleogel system offers mechanical protection and micellization ability during digestion. Therefore, the obtained oleogel particles-based emulsion has the potential to be utilized as effective encapsulation systems for hydrophobic molecules with controllable release by manipulating the biophysics of the chosen lipid and structuring agent network.