Browsing by Author "McClements, David Julian"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Fabrication, characterization and lipase digestibility of food-grade nanoemulsions
    (ELSEVIER SCI LTD, 2012) Troncoso, Elizabeth; Miguel Aguilera, Jose; McClements, David Julian
    The behavior of nanoemulsion-based delivery systems within the gastrointestinal tract determines their functional performance. In this study, the influence of particle radius (30-85 nm) on the in vitro digestion of nanoemulsions containing non-ionic surfactant stabilized lipid (corn oil) droplets was examined using simulated small intestine conditions. Nanoemulsions were prepared by a combination of high-pressure homogenization and solvent (hexane) displacement. Lipid droplets with different sizes were prepared by varying the oil-to-solvent ratio in the disperse phase prior to homogenization. The fraction of free fatty acids (FFA) released from emulsified triacylglycerols (TG) during digestion was measured by an in vitro model (pH-Stat titration). Nanoemulsions exhibited a lag-period before any FFA were released, which was explained by inhibition of lipase adsorption to the oil-water interface by free surfactant. After the lag-period, the digestion rate increased with decreasing oil droplet diameter (increasing specific surface area). The total amount of FFA released from the emulsions increased from 61% to 71% as the mean droplet radius decreased from 86 nm to 30 nm. The incomplete digestion of the emulsified lipids could be explained by inhibition of lipase activity by the release of fatty acids and/or by interactions between lipase and surfactants molecules. (C) 2011 Elsevier Ltd. All rights reserved.
  • Thumbnail Image
    Item
    Influence of particle size on the in vitro digestibility of protein-coated lipid nanoparticles
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2012) Troncoso, Elizabeth; Miguel Aguilera, Jose; McClements, David Julian
    The influence of particle size on the in vitro digestion of beta-lactoglobulin (BLG)-coated lipid nanoparticles was examined using simulated small intestine conditions. Nanoemulsions were prepared by high-pressure homogenization and organic solvent (hexane) evaporation. The effect of the initial organic phase composition on the size, microstructure, electrical properties, and digestion of the lipid nanoparticles was evaluated. The radius of the nanoparticles decreased (from 85 to 48 nm) as the solvent concentration in the initial organic phase increased (from 0% to 95%). The lipid digestion rate initially decreased with decreasing particle radius (for r = 85-59 nm), but then it increased (for r = 59-48 nm). This dependence is contrary to the usual assumption that lipid digestion increases with increasing lipid surface area. Our results suggest that the structure of the protein layer coating the lipid nanoparticles has an important effect on lipid digestion. (C) 2012 Elsevier Inc. All rights reserved.