Preparation of Pickering double emulsion stabilized by chitosan nanoparticles and evaluation of the effects of formulation parameters on the physical stability of formed emulsions

Emulsions stabilized by edible nanoparticles have attracted the attention of many researchers during the past ten years. However, very few studies have investigated the stabilization at least one interface of a double emulsion with a layer of edible nanoparticles. In this study, water-in-oil-in-water (W / O / W) Pickering double emulsions were prepared using chitosan nanoparticles as external aqueous phase stabilizers. Experiments were performed with Taguchi design. The effects of formulation parameters, including the ratio of internal aqueous phase content to the oil phase, initial emulsion content to external aqueous phase, and chitosan nanoparticle concentration on droplet size and stability of double emulsions were investigated. The results showed that the nanoparticle concentration had the highest effect (34.91%) on the droplet size of emulsions. Treatment No. 5, with 2: 8 of internal aqueous phase to continuous internal phase, 1: 9 of primary emulsion to continuous external phase, and a concentration of 0.65% nanoparticles, had the smallest droplet size compared to other treatments. Based on the results of the stability study, the ratio of the initial emulsion content to the external aqueous phase was more effective on the stability of the emulsions. The creaming index and coalescence were insignificant in treatments No.  5 and 7.