LAUSR

Abstract The bioaccessibility of β-carotene when administered in nanoparticles together with a lipid or when the lipid is administered separately (excipient) was investigated using an in vitro digestion model. The excipient oil was either in bulk form or in nano-emulsions. β-carotene loaded oil-free nanoparticles (NP) and oil-in-water nanoemulsions (NE) were fabricated using three different proteins (SPI, WPI or SC). Nanoemulsions without β-carotene and bulk oil containing the same quantity of lipids were mixed with NPs to study the effect of the form of the oil as excipient (NP + NE and NP + oil). Size distribution, changes in particle size and ζ-potential were determined as a function of time during simulated gastro-intestinal incubation. The addition of oil promoted the bioaccessibility of NPs, and dispersed nano-emulsions (NP + NE) was more effective than bulk oil (NP + oil). The lipolysis rate of the small dispersed oil droplets was higher and more micelles that attracted β-carotene were formed for NP + NE. However, the bioaccessibility for NP + NE was lower than β-carotene containing emulsions (NE group), probably due to the steric inhibition of lipolysis by more protein digestive products of the NP + NE group. This study suggests that the presence of lipids either in bulk or nano-emulsified form would increase the bioaccessibility of lipophilic nutrients in an oil-free nanoparticle.