Level of baking powder of batter weight

Fig. 30 Effect of baking powder level in sponges. • Skimmed milk powder.

If you suspect that an ingredient may have become contaminated with silicon you should discuss the problem with your supplier.

Reference

CAUVAIN, S.P. and HODGE, D.G. (1977) Collapse in sponge cakes. FMBRA Bulletin No. 6, December, pp. 214-222. CCFRA, Chipping Campden, UK.

Further reading

CAUVAIN, S.P. and CYSTER, J.A. (1996) Sponge cake technology. CCFRA Review No. 2. CCFRA, Chipping Campden, UK.

10.34 We are having problems with the bottom crust of our sponge cake products becoming detached after baking. We also notice that the corners of the product become rounded and the texture close. Why do these problems occur?

The problem comes from a lack of carbon dioxide in the formulation either because you are adding too little baking powder or because too much has been lost before the product reached the oven, or you are mixing the batter for too long.

In most cakes, but especially with sponges, getting a fine cell structure and light texture in the baked product requires the evolution of baking powder in the oven to inflate the air bubbles that have been incorporated during mixing. Even though the air bubbles expand under the influence of heat in the oven their degree of expansion is limited by Charles's Law, i.e. to 273 of their volume for each 1 kelvin (for practical purposes 1K = 1 °C). The evolution of carbon dioxide provides increases in gas volumes far in excess of that obtained purely from the temperature effect.

As the sponge batter expands during heating its relative density changes and this affects the heat transfer rate into the batter. Batters with high relative densities, i.e. low gas volumes, bake faster than those with low relative densities, because the gases involved act like an insulating material. Thus the more gas that is evolved during baking the slower the heat transfer rate and this leads to a more uniform expansion of the batter.

Steam is also generated during the baking process. This requires that the temperature in the product exceeds 100 °C. The presence of dissolved sugars raises the boiling point of the aqueous phase in sponge (Cauvain and Young, 2000) but the crust still sets fairly early in the baking process. The quantities of steam progressively evolved from the batter as the heat penetrates to the centre build up pressure under the top crust and detach it from the rest of the product. There is also a build up of steam at the angle of the base of the pan and its side, which prevents the batter flowing into that area. The rounding of this area of the product is often referred to as 'chamfering'.

The rate at which carbon dioxide gas is evolved depends on the rate of reaction between the acid component and the sodium bicarbonate. This can be regulated either by changing the acid type or its particle size. In the latter case larger particles are slower to react.

We suggest that you first investigate the effect of raising the level of the baking powder that you are using. This usually solves the problem. If it persists then you are probably using an acid that is too fast acting and we suggest that you change to a slower one. A rough guide for choosing a suitable acid is:

• fast acting acids - acid calcium phosphate (mono-calcium phosphate), tartaric acid and cream of tartar (potassium hydrogen tartrate).

• slow acting acids - sodium acid pyrophosphate and sodium acid aluminium phosphate.

The baking powder reaction rate can also be controlled by using an acid or sodium bicarbonate with a larger particle size; however, you must ensure that unreacted components are not left behind in the baked product as this can lead to flavour problems.

If you mix the batter for too long then the carbon dioxide gas evolved during the mixing process may escape from the batter rather than diffusing into the air bubbles. Cauvain and Cyster (1996) showed that this could happen even when using an apparently ' slow' acting acid such as sodium acid pyrophosphate.

References

CAUVAIN, S.P. and CYSTER, J.A. (1996) Sponge cake technology. CCFRA Review

No. 2. CCFRA, Chipping Campden, UK. CAUVAIN, S.P. and YOUNG, L.S. (2000) Bakery Food Manufacture and Quality: Water control and effects, Blackwell Science, Oxford, UK.

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