Impact of environmental stresses on orange oil-in-water emulsions stabilized by sucrose monopalmitate and lysolecithin

The food and beverage industry is trying to replace synthetic functional ingredients with more "label-friendly" ingredients in many commercial products. This study therefore examined the influence of environmental stresses on the stability of emulsions stabilized by a combination of lysolecithin and sucrose monopalmitate (SMP). Orange oil-in-water emulsions (5% (w/w) oil) stabilized by SMP (1%) and lysolecithin (0-0.5%) were prepared using high-pressure homogenization (pH 3). In the absence of lysolecithin, all emulsions were highly unstable to droplet aggregation, which was attributed to low droplet charge (weak electrostatic repulsion) and small SMP headgroup size (weak steric repulsion). Incorporation of 0.1-0.5% lysolecithin into the emulsions greatly improved their stability to droplet aggregation, which was mainly attributed to the increase in negative charge on the droplets (strong electrostatic repulsion). The addition of high levels of salt (NaCl) to the emulsions promoted droplet aggregation and creaming. Emulsions containing 0.5% lysolecithin were stable to heating (30-90 °C) in the absence of salt, but exhibited droplet aggregation and creaming when held at high (>50 °C) temperatures in the presence of 300 mM salt. This study has implications for the development of emulsion-based delivery systems for use in food and beverage products.