Effect of oil type and β-carotene incorporation on the properties of gelatin nanoparticle-stabilized pickering emulsions

The type of oil used and the introduction of bioactive compounds could strongly influence the microstructure and physicochemical properties of Pickering emulsions, which have yet to be fully understood. Herein, oil-in-water (O/W) Pickering emulsions were stabilized by autofluorescent gelatin nanoparticles with either corn oil or medium chain triglyceride (MCT) oil as references for commonly studied edible oils. The microstructure of the emulsions with changes in nanoparticle concentration, oil fraction (Phi), and oil type was investigated with confocal laser scanning microscopy (CLSM). An increase in nanoparticle concentration resulted in an increased thickness of the adsorption layers and number of droplets. Increasing Phi helped to form compact gel-like emulsions and improve the oxidation stability of the emulsions. The high oil-water interfacial tension and surface-active long-chain fatty acids of corn oil caused sparse packing droplet interfaces. Hence, corn oil emulsions were generally less stable than MCT oil emulsions, which was further demonstrated through studies of water holding capacity (WHC), long-term storage stability, and rheology. Furthermore, the incorporation of beta-carotene had negative effects on the formation and stability of the emulsions, especially for corn oil emulsions. The findings in this work may have important implications for exploiting Pickering emulsion formulations in real food products.

Automated summary

The study investigated the microstructure and physicochemical properties of Pickering emulsions stabilized by gelatin nanoparticles with different oil types and concentrations, using confocal laser scanning microscopy. Increasing nanoparticle concentration led to thicker adsorption layers and more droplets, while increasing oil fraction improved emulsion stability and oxidation resistance. Corn oil emulsions were less stable due to high interfacial tension and long-chain fatty acids, compared to MCT oil emulsions.