Active gelatin films incorporated with Pickering emulsions encapsulating hesperidin: Preparation and physicochemical characterization

In the present contribution, we focus on the fabrication and characterization of active gelatin-based films incorporated with oil-in-water (O/W) Pickering emulsions stabilized with chitosan nanoparticles (ChiNP) and encapsulating hesperidin (Hesp). Results revealed Pickering emulsions with d(3,2) of 5.4 mu m and PDI of 0.3. Hesp was found to improve the physical stability of the emulsions, suggesting that ChiNP adsorb more efficiently, in the presence of Hesp. Films were produced by the casting method incorporating different emulsion' levels (5, 10, 20, 30 and 50 g oil/100 g of gelatin). Microstructure analysis with confocal laser scanning microscopy (CLSM) images showed a similar droplets size and size distribution in the film matrix, endowing the films with homogeneous distributions of oil droplets over their 3D network architecture of films. Scanning electron microscope (SEM) suggested that this phenomenon might be related to Pickering stabilization effect of oil droplets incorporated into the film matrix. With increase of incorporation level, film' surfaces were more heterogeneous. Interestingly, the incorporation of Pickering emulsions was effective to produce films with good compatibility between interface of oil droplets and gelatin matrix. Films showed less resistance to tension, and more flexibility. The water vapor barrier properties of films improved by increasing the incorporation level. X-ray analysis revealed a good compatibility among the composite films. Films incorporated with encapsulated hesperidin showed a noticeable antioxidant activity. These findings are important to better design composite active films incorporated with Pickering emulsions, in order to optimize film formulation in a rational manner towards their eventual application as food packaging.