Stability and rheology of water-in-oil high internal phase emulsions containing continuous phase solid fat

Abstract

Solid fat added to the continuous phase of water-in-oil (W/O) high internal phase emulsions (HIPEs) was assessed for its effects on aqueous droplet size, microstructure, and rheology during storage for one month. The emulsions consisted of 76 wt% water and a continuous phase composed of up to 2.4 wt% fully hydrogenated soybean oil (corresponding to 10 wt% of the oil phase), polyglycerol polyricinoleate as surfactant, and soybean oil. The HIPE with 2.4 wt% solid fat showed the highest rigidity and brittleness at all-time points during storage, but also the lowest thixotropic recovery, which we ascribed to plastic failure of the fat crystal network. While fat added at all concentrations limited visual oil–water phase separation, its presence increased coalescence, particularly at higher concentrations. The present results demonstrated that the rigidity of W/O HIPEs may be tailored by addition of low amounts of solid fat; however, its addition may compromise physical stability.