Stabilizing oil-in-water emulsions with regenerated chitin nanofibers

Natural chitin is a highly crystalline biopolymer with poor aqueous solubility. Thus direct application of chitin is rather limited unless chemical modifications are made to improve its solubility in aqueous media. Through a simple dissolution and regeneration process, we have successfully prepared chitin nanofibers with diameters around 50 nm, which form a stable suspension at concentrations higher than 0.50% and a self-supporting gel at concentrations higher than 1.00%. Additionally, these nanofibers can stabilize oil-in-water emulsions with oil fraction more than 0.50 at chitin usage level of 0.01 g/g oil. The droplet sizes of the resulting emulsions decrease with increasing chitin concentrations and decreasing oil fraction. Confocal laser scanning micrographs demonstrate the adsorption of chitin nanofibers on the emulsion droplet surface, which indicates the emulsion stabilization is through a Pickering mechanism. Our findings allow the direct application of chitin in the food industry without chemical modifications.