Quiescent water-in-oil Pickering emulsions as a route toward healthier fruit juice infused chocolate confectionary

Abstract

We demonstrate a route toward the preparation of healthier fruit juice infused chocolate candy. Up to 50 wt% of the fat content in chocolate, that is cocoa butter and milk fats, is replaced with fruit juice in the form of emulsion droplets using a quiescent Pickering emulsion fabrication strategy. Fumed silica particles are used in combination with chitosan under acidic conditions (pH 3.2–3.8) to prepare water-in-oil emulsions, the oil phase being sunflower oil, molten cocoa butter, and ultimately white, milk, and dark chocolate. Adsorption of the polycationic chitosan molecules onto the surface of the silica particles influenced the particle wettability making it an effective Pickering stabilizer, as shown by cryogenic scanning electron microscopy analysis. The formation of a colloidal gel in the continuous (molten) oil phase provided the system with a yield stress, hereby giving it a gel-like and thus quiescent behaviour under low shear conditions, as determined by rheological measurements. This warrants a homogeneous distribution of emulsion droplets as settling through gravity upon storage under molten/liquid conditions is arrested. In our low-fat chocolate formulations the cocoa butter has the desired polymorph V structure, and neither sugar nor fat bloom was observed upon storage of the fruit juice containing chocolate confectionaries.