58-7 |
The effect of droplet composition on the stability of emulsions |
R. CHANAMAI1, G. Horn2, and D. J. McClements1. (1) Department of Food Science, University of Massachusetts at Amherst, Amherst, MA 01003, (2) Wild Flavors, Inc., 1261 Pacific Avenue, Erlanger, KY 41018 Food emulsions contain oil droplets that may vary widely in their composition, e.g. molecular weight, polarity and surface activity. Differences in the physicochemical properties of oil droplets might affect emulsion stability through different mechanisms, e.g. coalescence and ostwald ripening. Our objective was to examine the influence of droplet composition on the stability of model oil-in-water emulsions stabilized with Tween 20 or gum arabic. Oil phases were made by mixing decyl alcohol and hexadecane at different ratios. Aqueous phases were prepared with different amounts of Tween 20 or gum arabic. Surface tensions and interfacial tensions of oil phases were measured using a Wilhelmy plate tensiometer. Emulsions stabilized by Tween 20 or gum arabic were prepared with different droplet compositions. Particle sizes of emulsions were measured as a function of time at 25°C using a laser light scattering instrument. Droplet composition had a significant impact on emulsion stability. The particle size of emulsions made from oil phases with low interfacial tension increased more rapidly than those made from oil phases with high interfacial tension. Tween 20 stabilized emulsions were relatively stable to droplet growth, irrespective of the droplet composition. Gum arabic stabilized emulsions were stable when the droplet contained pure hexadecane, but became increasingly unstable to droplet growth as the decyl alcohol concentration in the droplet increased. Tween 20 lowered the interfacial tension more efficiently than gum arabic, which means that it protects droplet against coalescence more effectively. Our results are interpreted in terms of the influence of interfacial tension, emulsifier adsorption and coalescence stability of emulsions. The stability of emulsions is strongly influenced by droplet composition. A better understanding of these factors will have important implications for selecting oils or emulsifiers to enhance emulsion stability.
Session 58, Food Chemistry: Lipids, Emulsions and Antioxidants
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