Influence of Energy Density on Foamability: Comparison of Three Foaming Methods.

Abstract

The aim of the following study was to compare three different foaming methods and investigate the influence of the applied energy density (Evol) on the following foam properties: foam capacity (FC), sauter-diameter (d3,2) and interfacial area (IA). Foams were prepared with sodium caseinate, porcine gelatin, and egg albumen (c=1-10wt%) by whipping, spraying, and sparging employing up to 5 different Evol (3.3×104Jm-3-4.0×108Jm-3). First, whipping resulted in a FC that depended on the protein concentration and the type of protein with gelatin having the highest FC (837.2%±89.5%) at 1wt% among used the proteins. There was no linear trend between FC and concentration of gelatin whipped foams. In contrary, egg albumen whipped foams revealed a linear relationship between FC and concentration, with the highest foam capacity at c=10wt% (675.7%±83.0%). An increase in Evol led to an increase in FC and in IA, but in a decrease in d3,2 for all whipped foams. Second, spraying showed for all proteins an increase in FC with increasing concentration up to a plateau at >5wt% (caseinate), >2wt% (gelatin), >2wt% (egg albumen). No clear correlation between foam properties and Evol was observed for spraying. Third, sparging yielded a FC that was less affected by concentrations used in this study. Increasing the Evol during sparging led to a higher FC and IA, while the d3,2 slightly increased. Overall, no correlation between the methods, proteins, and energy density was obtained because the protein structure and foaming method influenced the foamability. However, Evol in combination with IA as output parameter was shown to be most suitable to compare the foamability of the proteins and the methods.