What causes sponge sandwiches to assume a peaked shape during baking
There are a number of different reasons why this problem should occur but a particularly common one is associated with the conditions in the oven during baking. Often the condition is caused by too rapid a heat transfer to the batter. In all baked products heat is transferred from the surface to the centre and in the case of round products much of the heat transfer is along the radii from outer edges to centre. In the case of round sponges the surface area is large relative to its thickness so that a small portion of batter in the centre is the last to bake and the considerable expansion forces present exploit the radial effect and force the sponge to peak. The most obvious sources of too rapid a rate of heat transfer are as follows:
• Too high a baking temperature in the oven. Robb (1987) showed that sponge cake peaking was entirely dependent on baking temperature and independent of baking time. The solution is to lower the baking temperature but you may also have to increase the baking time in order to remove sufficient water from the product.
• Excessive top heat, particularly in deck ovens. The high radiant heat component in such cases acts like too high a baking temperature. In such cases the 'baking temperature' may appear to be satisfactory. If you cannot balance the heat components in your oven steaming the chamber before you are ready to bake is a good way of removing excess radiant heat.
• In the case of ovens that bake by forced air convection too high an air velocity can cause the product to peak. Cauvain and Screen (1988) showed that high air velocities in forced convection ovens increased sponge cake peaking even when the temperature was 'normal'.
Other possible reasons for the problem include the following:
• Over-treatment of the flour, either from excessive chlorine treatment (see 2.10) or excessive heat treatment (see 2.9). In the latter case you might also expect that the flour has a ' burnt' odour which may carry through to the product. If you suspect that this may be the cause we suggest you discuss the problem with your flour supplier.
• A lack of carbon dioxide gas because the baking powder level is too low or because the rate of reaction has been too fast and much of the carbon dioxide gas has been lost before the batter reaches the oven.
• Insufficient mixing so that there are too few gas bubble nuclei present in the batter for carbon dioxide inflation.
CAUVAIN, S.P. and SCREEN, A.E. (1988) Heat-flux measurement and sponge cake baking. FMBRA Bulletin No. 4, August, pp. 156-162, CCFRA, Chipping Campden, UK.
ROBB, J. (1987) Cake baking conditions. FMBRA Bulletin No. 4, August, pp. 150-158, CCFRA, Chipping Campden, UK.
Continue reading here: How do we convert a plain sponge recipe to a chocolate form
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