In this article, we examined a new environmentally friendly process of introducing a hardly soluble active additive into chitosan edible films using the example of rutin, which has antioxidant and nutraceutical effects. The process is based on the formation of submicron particles of rutin in the chitosan matrix, during the short-term (10 s) mechanical activation of mixed aqueous solutions in a metastable state using a rotor-stator device. It is shown that mechanical activation accelerates the nucleation of rutin and prevents aggregation of the resulting particles due to embedding them in the polymer structure. Chitosan samples differing in molecular weight and deacetylation degree were used to form the films. It was found that the rutin particles size decreases with an increase in its concentration in supersaturated solutions, as well as with an increase in the chitosan solution viscosity. Rutin particles had a needle-like shape with a diameter of 0.40–0.75 μm and showed a reinforcing effect, increasing the tensile strength of chitosan films by 25–40%. Chitosan films containing rutin were smooth, uniformly yellow colored, and had lower water vapor permeability compared to films made of chitosan alone.
