Edible Pickering Emulsion Stabilized with Silkworm Particles

Edible Pickering-type emulsions, with which proteins can be ingested in an invisible state, could be successfully fabricated by using silkworm particles as an emulsion stabilizer and castor oil as an oil phase. Zeta potential measurements by electrophoresis confirmed that the silkworm particles were not electrostatically stable under acidic conditions (pH 4) and tended to aggregate in the aqueous media. On the other hand, under basic conditions (pH 10), the particles, whose surface was highly negatively charged, dispersed in the aqueous media via electrostatic repulsion. Homogenization of the silkworm particle aqueous dispersion and castor oil under acidic conditions led to the formation of oil-in-water Pickering emulsions, which were stabilized by the silkworm particles adsorbed at the oil–water interface. After removal of the water-soluble components existing in the silkworm particles via purification, the adsorption density of the silkworm particles on the oil–water interface of the droplets increased and more stable Pickering emulsions were formed. The oil droplets creamed up/sedimented during the storage but could be well redispersed by handshaking. Furthermore, it was demonstrated that the higher the silkworm particle concentration of the aqueous dispersion, the smaller the droplet size of the emulsions and the more stable emulsion against coalescence (at least for 3 months).