Cellulose nanocrystal/chitosan ratio in Pickering stabilizers regulates vitamin D3 release

This study investigated the use of cellulose nanocrystals (CNC)/chitosan (Chit) polyelectrolyte complex as a stabilizing agent for Pickering emulsions. We demonstrated that chitosan reduces the surface charge of CNC improving the emulsification process. An optimal stabilizing complex containing 1% chitosan results in emulsions with minimal zeta potential (3.2 ± 0.3 mV), droplet size (2.8 ± 0.8 μm), and creaming index (19.8 ± 1.0%) values, along with high stability during storage, a change in pH, and high centrifugal forces (up to 2000 g). The study also showed that the maximum neutralized surface charge of the CNC in the CNC-Chit complex allows for effective adsorption on the surface of sunflower oil droplets, producing a denser stabilizing layer with a smaller droplet size. Additionally, chitosan addition is linked to improved stability and higher viscosity, with little dependence on ionic strength and temperature. Potentiometric titration revealed that compared with sulfated CNCs, five times less chitosan is needed to neutralize the negative surface charge of acetylated CNC. The wettability of a hydrophilic surface depends on the surface charge of the complex, and the wettability and adhesion performance increase with increasing chitosan content. Additionally, we showed that tuning the stabilizer composition can change the bioaccessibility of lipophilic compounds during oral administration. Graphical Abstract