The Science of Cake Bakery . . .

 
(A Simple Butter Cake)

From time to time readers ask me why their cake sank in the middle when baking. They always say something along the lines of: "I followed the recipe perfectly, but it still sank. What did I do?!" While it's impossible for me to know exactly what happened in any specific occasion without my actually being there, and I can't pretend to be an expert baker myself, these are the top 5 things you should look out for which may help to keep your cake from sinking the next time you bake:

1. Old Baking Powder:   Baking powder may only account for a tiny percentage of your entire cake ingredients, but it can ruin the whole thing if you're not careful! Remember that baking powder only stays fresh for about 6 months to a year, so date them when you buy them, and toss and replace any containers that have been hanging around too long.

Not sure if yours is still good? Take 5 seconds to test it before you start baking by placing a teaspoon of baking powder in about a 1/2 cup of hot water. If still good, it should start to bubble rapidly. If nothing (or barely nothing) happens, it's time to head to the store.

2. Too Much Leavening:  As counter-intuitive as it might sound, adding too much baking powder, baking soda, or yeast to a cake will cause it to sink as the amount of air that is created within the cake will be more than the structure can support and the whole thing will come crashing down.

Never add additional baking powder or other leaveners to self-raising flour or cake mixes (they already have it mixed in), and always be sure to read a recipe clearly and measure carefully.

When in doubt, remember that the average ratio for baking powder to flour is 1 to 1.5 teaspoons per cup of AP flour; so if you read a recipe that calls for something way above that, it's probably an error.


3. Overbeating:   this is probably one of the most common reasons why cakes sink. I'm not sure what it is, but we all seem to have a natural tendency towards overbeating cake batter until it is smooth and creamy. This is even easier to do when we rely on the trusty old Kitchen Aid or food processor to do our mixing for us. But beating in too much air into the batter once the dry and wet ingredients are combined will only cause the batter sink.

Go ahead and work the air in when creaming the butter, sugar, and eggs, but as soon as you add the flour mixture, remember that it's ALL about the light hand. Fold the dry ingredients through the wet only until they are just combined, then delicately divide and pour into your cake pans. If adding anything at the end (food coloring, chocolate chips, nuts, etc.), continue to work the addition through the batter as gently as possible in a flowing folding motion.



4. Oven Temperature: an oven that isn't properly calibrated and runs either too hot or too cold, could easily make for a falling cake. If possible, spring for an external oven thermometer (you can find them in the $15-$30 range at stores like Bed, Bath, and Beyond) to make sure that when it says 350 on the dial, it's really 350 inside the oven.

Also, don't be tempted to peek inside that oven for at least the first 80% of the suggested baking time. Remember that each time you open the oven door, the temperature inside can drop as many as 10 degrees. These tiny fluctuations in temperature can affect the even rising of the cake. 

5. Timing:  Unless a recipe specifically calls for it, don't let a finished batter sit for very long before baking. 20-25 minutes while the first batch bakes is fine; a few hours while you run out to pick up the kids and finish some errands is not. I always strive to have my cakes in the oven as soon as I have finished mixing them, unless of course I have been otherwise instructed in a recipe.

Remember that the minute the wet and dry ingredients meet, a chemical reaction starts to take place (like those baking soda volcanoes we all made in 7th grade science class). To get a light, fluffy, and beautifully raised cake, you want that chemical reaction to take place inside the oven as the cake bakes so that the air that is created gets sealed into the baking cake. If your batter is sitting on the counter or on the fridge, the air created inside will just escape into the room, and come time for baking, there will be less to lift the cake up.
  

 
(Irish Apple Cake)

And... a few bonus tips!

Preheating IS important. Depending on your oven, it can take as long as 30 minutes for it to reach the optimal baking temperature. Always be sure to do that first before getting on with your recipe or you'll end up with an uneven, lumpy cake.

Baking Powder and Baking Soda are NOT interchangeable. Though baking powder contains baking soda, it also has other components that act as a catalyst for all that good air-creating cake-rising action, and is used in recipes that don't have acidic elements. Baking soda usually works along with an acid (lemon juice, buttermilk, yogurt, chocolate, etc.). Some recipes call for both, but that doesn't mean that you can skip one or the other; if it calls for both, be sure to use both.   



(A Lemon and Pistachio Cake)

Center your oven rack. Unless otherwise told, position your oven rack in the center and place the cake pans right in the middle of the rack. If baking two cake layers at once, place them on the same rack side-by-side; don't put one on top of the other; they won't bake evenly that way.

As much as possible have all your ingredients at room temperature. I know it is very tempting to want to be in a rush and to think that it can't possibly hurt if all of your ingredients are at different temps.  When it comes to the science of baking however, this variance in temperature between ingredients can make a really big difference when it comes to the end result. Bake a cake with frigid butter and eggs and you may end up with something resembling a pancake. That’s why some recipes call for “room temperature” ingredients, a frustratingly general concept, especially from a scientific point of view.  Baking with room temperature butter helps to create "fluffiness."  Too warm or too cold butter can result in either too few air bubbles, or air bubbles with don't hold their shape and flatten quickly. 

Eggs are also crucial in giving loft to baked goods. The white of the egg is 90 percent water and 10 percent protein; when you beat an egg, it’s the protein that traps the air bubbles, and when incorporated into baked goods, these bubbles expand in the heat of the oven. Egg whites can be whipped up to eight times their volume, but this maximum air-trapping happens only when the eggs are warm; in warm eggs, the whites and yolks are looser, so it’s easier to incorporate air into them (which is the whole point).

Warmer eggs are also better when you’re mixing batter for cakes and cookies, because if you introduce cold eggs to a warmer butter-sugar mixture, the fat in the butter could harden. That would impede integration of the butter and eggs, which is why you’re creaming them to begin with.

But you do want your eggs to be cold if you need to separate the whites and yolks. Cold eggs are easier to separate, so if your recipe calls for the yolks and whites to be separated, do it before warming the eggs. 



So now that I have told you all that I can about the science of baking and shared all of my wisdom in great cake bakery, I think it's only fair that I share my absolute favourite cake recipe with you.



 It's a deliciously buttery sponge, filled with fresh raspberries and baked into two moist layers. Sandwiched together with a lovely vanilla butter cream icing and some seedless raspberry jam, and then drizzled with more sweetness. This is one very moreishly scrummy cake.



 *Raspberry Celebration Cake*
Cuts into 12 scrummy slices
Printable Recipe

This is the cake I always bake for summer birthdays.  A light moist sponge, filled with lovely raspberries, butter cream icing and seedless raspberry preserves.  Top with a sweet glaze and serve with more raspberries.

For the Cake:
175g of caster sugar (3/4 plus 1/8 cup)
175g of butter, softened (13 TBS)
4 large free range eggs, separated
100g self raising flour (a scant 3/4 cup)
1 tsp baking powder
100g ground almonds (1 scan't cup)
a few drops of almond extract
125g of fresh raspberries (a heaped cup)

For the buttercream:
75g of butter, softened (1/4 cup approx.)
125g icing sugar, sifted (about 3/4 cup)
few drops vanilla

For the glaze:
100ml icing sugar sifted (1/3 cup approx.)
water to thin 

 

Also about 4 heaped dessertspoons of seedless raspberry jam

Preheat the oven to 180*C/350*F/Gas mark 4.  Butter two 8 inch sandwich cake tins.  Line the bottoms with parchment paper.  Set aside.

Cream together the butter and sugar until pale and fluffy.  Beat in the egg yolks.  Sift the flour and baking powder over the creamed mixture and then fold in using a metal spoon.   Fold in the ground almonds and exract.  Fold only until all traces of the flour have disappeared.

Beat the egg whites until they just hold their shape.  Fold them in gently, by thirds, being careful not to overmix and lose the lightness of the whites.  Lightly fold in the berries.  Divide between the two prepared cake tins and level off carefully.

Bake in the heated oven for 30 to 35 minutes, just until they test done.  A toothpick inserted in the centre should come out clean and they should spring back when lightly touched on top.

Remove from the oven.  Let cool in the tins for five minutes, then tip out onto wire racks, peel off the baking paper and allow to cool completely.

Make the buttercream by beating together all the ingredients until smooth and creamy.

Place one cake, bottom side up on a cake plate.  Spread completely with all the buttercream.  Spread the raspberry jam over top of the buttercream and then top with the other cake layer, placing it right side up.  Whisk together the icing sugar for the glaze and enough water to make a smooth drizzable mixture.  Drizzle decoratively over the top of the cake.  Allow to set, then dust with more icing sugar if desired.

Have a great weekend!