Stabilization of water-in-oil emulsions by submicrocrystalline alpha-form fat particles

The results presented in this study confirm previous knowledge and stress t he need for both hydrophobic emulsifiers and submicronial fat particles to stabilize water-in-vegetable oil emulsions. It was demonstrated that polygl ycerol polyricinoleate (PGPR) is superior to glycerol monooleate and/or lec ithin, but is incapable of stabilizing these fluid emulsions for sufficient storage periods. Fluid emulsions, unlike margarine, exhibit high droplet m obility and are susceptible to flocculation and coalescence. It was also de monstrated that submicronial alpha-form crystals of hydrogenated fat can be obtained in the oil phase by the flash-cooling process. The crystals are h omogeneously almost mono-dispersed and exhibit insufficient stability again st flocculation and phase separation. The use of an emulsifier (PGPR) in th e fat crystallization process was very helpful in decreasing the aggregatio n and flocculation processes. The alpha-form (mixed with beta'-form) submic ronial crystals can stabilize water-in-oil emulsions only in the presence o f food emulsifiers, provided the concentration of tristearin is limited to 1.0-2.0 wt% (to prevent phase separation and high viscosity) and the PGPR i s added at sufficient concentrations (PGPR/tristearin ratio of 2.0 or more) . Ideally stable (for over 6-8 wk) fluid emulsions can be formed in systems composed of fat submicrocrystalline hydrophilic particles and food-grade e mulsifiers. These water-in-oil emulsions can serve as the basic preparation for any food-grade water-in-oil-in-water double emulsion.