The Role of Starch Granules on the Formation of Gas Cells in Sponge Cake

Abstract

This study clarifies the role of starch in the process of forming the structure of sponge cake. Sponge cakes are usually made of wheat flour, egg, and sugar as main ingredients. However, the experimental system for cakes made with these ingredients becomes too complex to study the behavior of starch granules in cake batters due to the viscous nature of materials such as wheat flour proteins. For this reason, either wheat starch or potato starch was substituted for wheat flour so that sponge cakes could be prepared in the most simple system possible. The structure of gas cells was observed in sponge cakes made from either wheat or potato starch through a scanning electron microscope. Gas cells were spherical and continuous in the wheat starch sponge cake, whereas the gas cells were mostly nonspherical in the potato starch sponge cakes, the gas cells having been destroyed, forming discontinuous layers. The difference in the gas cell structure of these cakes is dependent partly on whether or not starch granules are nuiformly dispersed on the surface of air bubbles in cake batters. The wheat starch granules were distributed uniformly on the surface of air bubbles, but the potato starch granules were not. The difference in the gas cell structure may also be attributed to the fragility caused by the swelling and deformation of the potato starch granules, as observed by the Amyloviscograph.