Functional properties of cellulose derivatives to tailor a model sponge cake using rheology and cellular structure analysis

The functional properties of cellulose derivatives were studied to understand their specific and respective roles in the structure formation at each step of the process of a model sponge cake composed of hydroxy propyl methyl cellulose (HPMC) and methylcellulose (MC) and native corn starch. During batter preparation, the shear-thinning behavior and the quantity of air in the final product increased with the HPMC/MC ratio. HPMC controlled the viscosity of the system and limited bubble loss during starch addition. However, the lower the batter density, the higher the inhomogeneity of the final structure. During baking, the MC governed the sol-gel transition but HPMC slightly impeded it, and the gelling temperature decreased along with the HPMC/MC ratio. Because of the cold water binding capacity of starch, the concentration of HPMC/MC increased in the continuous phase during the batter preparation, decreasing the gelling temperature. A compromise in the HPMC/MC ratio giving a gelling temperature of about 54 degrees C was necessary to have a homogeneous final structure. Image analysis of the cellular structure confirmed the results by a classification of the products. The higher the MC concentration, the smaller the cells and the thicker the cell walls. An analysis of the effect of the mixing time after starch addition showed that the density after baking increased along with it. It was possible to obtain different crumb structures from a same composition by only changing the mixing time. Finally, a hypothesis about the structuring mechanisms of a model sponge cake at each step of the process was proposed using a schematic representation of the structure at three different scales and along the process steps. (C) 2017 Elsevier Ltd. All rights reserved.