Sponge cakes shrink because they contain eggs. When the egg cooks, the water inside the egg evaporates, leaving behind air pockets. The air pockets expand when the cake cools down, causing the cake to shrink.
Top 14 sponge cake problems and how to fix them
Sponge cakes are delicious desserts that are perfect for birthdays, holidays, and other special occasions. However, there are certain problems that can arise when making sponge cakes.
Here are the top 14 sponge cake problems and ways to fix them.
1. Cake is Crumbly
If you have crumbly cake or dry, it means you have overbeaten the batter too much.
Overbeating causes the gluten in the flour to develop into a tough network of protein strands which traps all the moisture from the liquid ingredients for baking within the mixture.
This results in a dense cake with little volume. To avoid this problem, beat only until soft peaks form on the surface of the batter.
2. Too Dry or Moist
A moist sponge cake has a light texture while a dry one feels heavy. If your cake seems very wet or sticky, then add more sugar to balance out the sweetness.
On the contrary, if your cake is not sweet enough, reduce the amount of sugar by adding some milk powder or cornstarch. You may also use an alternative ingredient such as cocoa powder instead of sugar.
3. Not Rising Properly
When mixing together the dry ingredients and the wet ingredients, make sure both sides of the bowl are well mixed before proceeding to the next step. Have a proper ingredient ratio.
Also, don’t forget to grease the pan properly so that the cake will rise evenly during cooking.
4. Sponge Cake Separation of Eggs
Separated eggs tend to be runny and cause the cake to collapse.
Make sure you separate each egg carefully and wash off any excess yolk using cold running tap water.
5. Stiffened Batter
To prevent stiffening of the batter, mix the butter first and let it melt completely before adding the rest of the dry ingredients.
Alternatively, you could try melting the butter in a microwave oven at medium heat for about 30 seconds.
Overcooking leads to a hard crusty exterior but undercooked interior.
So check whether the center of the cake is cooked through by inserting a toothpick or skewer into the middle of the cake. It should come out clean without any traces of wet cake.
Undercooked cakes taste bland and lack flavor. They’re best served warm rather than hot.
For example, serve warm slices of cake straight from the oven. Or bake the cake again once cooled down.
8. Sponge Cake Batter Runs Out Before Cooking Time Is Up
Baking time varies depending on different factors like preheated oven temperature, humidity, altitude etc. Therefore, always use an oven thermometer and follow the instructions provided on the packaging.
In case the recipe calls for 15 minutes’ baking time, start checking the cake’s progress every 5-10 minutes.
Once done, remove the cake immediately from the oven and allow it to cool down fully before slicing.
9. Shrinks After Cooked
After being baked, most types of cakes become softer due to steam loss and lack of structure. The result? A shrunken cake!
Don’t worry though because there are ways to fix this issue. Simply place the cake back in the preheated oven for another 10 – 20 minutes.
10. Doesn’t Rise Enough in Center
The reason why your cake doesn’t rise up high enough might be due to insufficient leavener and lack of structure. Try increasing the quantity of baking soda used in the recipe.
Another option would be to replace half of the baking soda with cream of tartar.
11. Fluffy on Top but Hard at Bottom
This problem can occur when too much flour was added to the cake mixture.
To avoid this, either decrease the amount of flour or increase the liquid content.
12. Browning cakes During Baking.
If your cake starts browning unevenly, it means that the top layer is getting hotter than the bottom part.
This happens because the air trapped inside the cake expands faster than the outer surface which results in unequal heating.
To solve this problem, cover the whole cake loosely with aluminum foil until the end of the successful baking process.
13. Sponge Cake Filling Leaks Through
When making a filling such as jam, chocolate ganache, mousse, or custard, make sure not to overfill the cake so that the cake won’t get soggy.
If necessary, use an offset spatula to spread the filling evenly across the entire cake.
14. Crust Gets Tough
A tough crumb texture occurs if the cake has been stored improperly. Store the cake tightly wrapped in plastic wrap or aluminium foil.
Also, don’t store the cake in direct sunlight since excessive exposure will cause the sugar crystals to dissolve.
A science theory about cake collapse:
I have baked a sponge cake and it is shrinking. I am not sure if this happens to everyone or just me, but my cakes always seem to shrink when they are cooling down.
Is there anything that can be done about this?
It’s because the batter has risen in volume during cooking. The rising causes the air inside the cake to expand as well.
When you take the cake out of the oven, the heat escapes through the sides leaving behind less gas inside the cake.
As a result, the cake shrinks. You could try adding more eggs to compensate for the lost volume.
Alternatively, you could add some extra egg whites to help add extra structure.