Texture and stability of aerated food emulsions - effects of buoyancy and Ostwald ripening

In this paper, we analyze the effect of buoyancy and Ostwald ripening on the spatial dependence of bubble size distribution as well as for the volume fraction of incorporated air in a food emulsion. Experimental data as well as numerical simulations have shown that buoyancy results in a vertical spatial heterogeneity of air volume fraction as well as bubble size distribution with time. Simulation of the Ostwald ripening process has shown that for the time period of interest (1 month), the fraction of the small and large size bubbles increased at the expense of the intermediate size bubbles. In the system studied (mayonnaise aerated to about 50 vol.%), it was found that buoyancy is the predominant destabilizing factor. However, a parametric analysis reveals that in systems where the bubble size distribution has a smaller mean value, Ostwald ripening could also destabilize the aerated product significantly. For aerated mayonnaise, it is shown that increasing the yield stress of the continuous phase can prevent degradation of texture, by preventing the rise of the air bubbles due to buoyancy. (C) 2003 Elsevier Ltd. All rights reserved.