Factors affecting the Formation and Stabilization of Gas Cells in Bread Doughs

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Publisher Summary This chapter focuses on the factors affecting the formation and stabilization of gas cells in bread doughs. When the Chorleywood Bread Process was first introduced, the need for a fundamental understanding of the process became apparent. There is still limited understanding of the mechanisms involved in bread production at a molecular level. Wheat flour dough is a complex dispersion of air cells, lipid droplets, and starch granules in a continuous hydrated gluten matrix. A uniform distribution of bubble nuclei are created during mixing. Carbon dioxide diffuses into the bubble nuclei in proof to form gas cells and to create a semi-solid foam and on baking, this becomes a sponge-like structure. The bubble wall material must be present in the aqueous phase of the dough and be able to adsorb rapidly at the gas-liquid interface. The bubble walls must have considerable visco-elasticity as the bubbles expand to occupy >90% of the total volume. The chapter reports measurements on aqueous extracts from flours of different baking qualities. Their interfacial properties were determined using a Langmuir trough and a surface rheometer. The response of films to compression and expansion corresponds to the forces the bubbles experience during proof and in the oven and their response to shear reflects forces during mixing.