Chitin nanocrystals/alginate complex for tuning stability, rheology and bioavailability of cholecalciferol in Pickering emulsions.

In this paper we investigate polyelectrolyte complexes of sodium alginate (Alg) and chitin nanocrystals (ChNC). Formation, stability and transport properties of sunflower oil-in-water emulsions stabilized by ChNC-Alg complex were studied using dynamic light scattering (DLS), laser Doppler electrophoresis, optical microscopy, potentiometric titration, rheology and simulated digestion. It has been established that during emulsions formation, the ChNC-Alg complex is rearranged at the interface and the formation of a two-layer coating of the droplet occurs. Stabilized O/W emulsions are stable during storage, in the pH range 2-9 and centrifugal acceleration up to 2000 RCF. Presence of Ca and Na ions in the range up to 150 mM has virtually no effect on the droplet size. Inclusion of 5 wt% Alg in the ChNC-based emulsion stabilizer system leads to a drop in Gibbs adsorption >16 times compared to the ChNC-stabilized emulsion, increase in viscosity and rheopexy index of the systems. We found that chemical properties of colloidal phase surface and rheological properties of emulsions stabilized by ChNC-Alg are mostly dependent on the droplet size, not the type of oil as a result of a comparative study of sunflower oil/liquid paraffin oil. Emulsion drops of an optimized composition are stable in the upper parts of the model gastrointestinal tract system and transport vitamin D3 to the small intestine without significant losses. The bioavailability of vitamin D3 in emulsions stabilized with the ChNC-Alg complex is higher than for emulsions stabilized with ChNC alone.