A kinetic study of oil-in-water emulsion formation stabilized by rice husk ash and lecithin

Many food products are in the forms of emulsions whereby at least one phase is dispersed in other phases. Since emulsions consist of different immiscible phases, they tend to be unstable with time despite the incorporation of emulsifiers. In this study, the stabilities of oil-in-water (O/W) emulsions prepared using emulsifier mixtures of rice husk ash (RHA) and lecithin were monitored with time and destabilization kinetics of emulsion were studied. Rice husk ash of 2% was combined with various lecithin concentrations ranged from 0.5% to 3%, and they were added into the oil phase. The emulsification was carried out using a rotor stator homogenizer. The results showed that the rate of emulsion destabilization followed the first order kinetic model. The lowest value k₁ of 0.4 × 10⁻³ minute⁻¹ was obtained from the combination of 2% RHA and 2% lecithin. This implied the synergism action of RHA with lecithin in stabilizing the emulsion. The mixtures of lecithin and RHA seemed to be quite promising in stabilizing the O/W emulsion system for designing healthy O/W emulsion food-based products. (paper)