Elaboration and characterization of barley protein nanoparticles as an oral delivery system for lipophilic bioactive compounds

This is the first report in which barley protein nanoparticles were prepared with the aim of developing a delivery system for lipophilic bioactive compounds at ambient temperature using high pressure homogenization. No organic solvents or crosslinking reagents were involved in the nanoparticle preparation. Effects of processing conditions and formulae on particle size and size distribution were investigated. Optimal nanoparticles with regular spherical shape, small size (90-150 nm) and narrow size distribution (PDI < 0.3) could be achieved at a protein weight concentration of up to 5% when the oil/protein ratio was maintained within a range of 1 to 1.5. These nanoparticles exhibited high zeta-potential (about -35 mV), high payload (51.4-54.5%) and good stability without the use of surfactants. As shown by the release test, though the bulk protein matrices of nanoparticles were degraded in the simulated gastric tract, even smaller nanoparticles were released and bioactive compounds were protected by a layer of barley protein. Then, complete release occurred in the simulated intestinal environments due to pancreatin degradation. In vitro studies showed that barley protein nanoparticles are relatively safe and could be internalized by Caco-2 cells and accumulated in the cytoplasm.