Chemical aeration

Abstract

The control of the relative density or volume of baked goods to manufacture products with the desired eating characteristics is a critical function in modern manufacturing practice. However, the ways to achieve this control have been available to bakers for centuries. They start with the incorporation of air into batters, doughs and pastes to form a nucleus of gas cells which will expand during baking to make the final product. The expansion of the initial gas cells can be achieved by the use of chemical aerating agents and/or yeast, but in all cases the evaporation of water in the batter, dough or paste plays a major part in the expansion process. The relative importance of the various aerating systems in a product formulation is dependent on many factors and can be different at different stages in the process. Thus, for example, the expansion of gas cells by water is dependent on the excess vapour pressure in the product as it is baked. Hence the internal batter temperature is critical since water vapour pressure will increase progressively as the temperature increases towards the boiling point of water. The amount of expansion at any stage in the production process will also be affected by the viscosity of the batter and the porosity of the walls of the gas cells, especially those at the surface. This chapter is not intended to cover all aspects of the chemistry and physics of confectionery production, but the reader should appreciate that an understanding of the chemistry and physics of any production system is necessary to achieve effective control. Thus the development of a well controlled cake manufacturing process requires the technologist to understand the critical factors in foam generation and batter stabilization and the appropriate aerating system for use in manufacture.