Influence of process parameters on microstructure of food foam whipped in a rotor-stator device within a wide static pressure range

Whipped foods like ice cream, chocolate mousse, fresh cheese or bakery products are increasingly popular. Related research in the field of foam process engineering is concerned with design and characterization of new aeration processes, generating foams with a well defined microstructure. The perception properties, stability and flow behavior of food foams strongly depend on their gas fraction and bubble size distribution. Ideally, foams contain smallest possible gas bubbles of equal size. Within this study, experiments on a rotor-stator whipping device were conducted and the influence of several process parameters on the resulting foam microstructure determined. All foams were produced from a model system containing a total milk protein and guar gum and were characterized by their overrun and bubble size distribution. The impacts of residence time in the dispersing flow field, rotational velocity of the whipping tool, overrun and pressure on the bubble size distribution were quantified. The traditional application of back-pressure during continuous foaming leads to bubble expansion when the back-pressure is released whereas a new way of foaming under partial vacuum conditions, developed within this work, allows for subsequent bubble shrinkage. (c) 2005 Elsevier B.V. All rights reserved.