Ice cream, bread, popcorn, meringue, and marshmallows are just a few examples for aerated foods. The formation and stabilization of aerated foods are influenced by numerous parameters such as ingredients, viscosity, foaming mechanism, and gas volume fraction. One foaming mechanism that has been scarcely investigated is called high-pressure foaming.  

High-pressure foaming has a high application potential for the food industry with respect to the formation of micro-cellular products. The experiment design allowed for the systematic study of the gas dissolution and  foam formation under defined pressure, temperature, and flow conditions. Oil-in-water emulsions were chosen as a model system and were saturated with carbon dioxide at elevated pressures up to 50 bar. This showed that dissolved gas fraction, emulsion viscosity, and shear stress have a major influence on foam formation. This was confirmed by video analysis capturing nucleation, growth and destabilization of bubbles as a function of pressure, supersaturation, and time.

The results of this work provide an understanding of the high-pressure foaming mechanism from a rheological perspective, which are the backbone for the design of related processes. These principles were adapted for gluten-free dough to partially compensate its low gas-holding capacity. The process was successfully implemented in a foam extrusion process on a semi-industrial scale, showing that this technology improves the density, foam structure, texture and sensory properties of gluten-free bakery products.

This research was conducted at the Laboratory of Food Process Engineering at ETH Zürich.

The full research dissertation can be viewed and downloaded online, here.  If you would like more information or would like to discuss this research further please contact Volker Lammers.

Each year EFFoST and Cargill present the student of the year award to six students and also give them the opportunity to showcase their research. In this article Volker Lammers who won the 3rd prize for the PhD student of the year award discusses his research. Currently Volker is leading the Process Engineering group at the German Institute of Food Technologies (DIL e.V.).