Lauric acid adsorbed cellulose nanocrystals reduced the in vitro gastrointestinal digestion of oil-water pickering emulsions

Abstract

An in vitro gastrointestinal tract (GIT) fate of beta-carotene-loaded oil-in-water Pickering emulsions stabilized with lauric acid-adsorbed cellulose nanocrystals (CL) was investigated. Different concentrations (0.5, 1.0, 1.5 and 2.0%, w/v) of CL and pure cellulose nanocrystals (CNC) were used. During in vitro digestion, the effects of CL and CNC and their concentrations on the lipid droplet diameter (D 4,3 ), zeta potential, microscopic structure, phase stability (creaming index), degree of lipid digestion (free fatty acid release), and bioaccessibility of loaded beta-carotene were recorded. The Pickering emulsions stabilized with levels of CL above 1.0% (w/v) were stable against lipid droplet flocculation and coalescence and impeded the increase of D 4,3 (p ≤ 0.05) throughout the GIT phases. A significant increase in the D 4,3 was recorded for the emulsion stabilized with CNC due to flocculation and coalescence of lipid droplets. Instead of electrostatic repulsion stabilization, Pickering emulsions stabilized with CL displayed steric stabilization activity at the lower pH of the gastric phase, where the lowest zeta potential of less than +10 mV was found. The Pickering emulsion stabilized with CNC had significantly higher lipid digestion (∼63%) than stabilized with CL (∼52%). Average bioaccessibilities were up to 65% for CL stabilized Pickering emulsions and 70% for CNC-stabilized Pickering emulsions. CL can maintain emulsions phase stability by retaining lipid droplet size, reducing lipid digestibility, and prolonging the release of lipophilic nutrients. Other modifications of CNC may be required to release such nutrients in the small intestine, and in vivo studies are needed to verify in vitro assays. • Modifying nanocellulose with lauric acid improved emulsion stability but delayed the release of beta-carotene for absorption in an in vitro digestion model system. • Other types of chemical modification may be necessary to deliver phytonutrients for absorption in the small intestine.