Why I love the science of Rose Levy Beranbaum: butter & unbleached flour

M

marilynfl

Moderator
Rose has a FAQ page and the question was asked about cupcakes sinking in the middle:

Q:"the cakes rise beautifully in the oven - but then about 5 minutes after I take them out they begin to sink in the middle. What do you think could be the problem? I'd love for them to be just slightly rounded on top, for the sake of presentation."

Rose's Answer:

The Wrong Type of Flour

If using unbleached flour for a butter cake in which the butter is used in softened form, as opposed to melted as for a genoise, the cake will dip in the center about 5 minutes after baking. This is because the smooth flour particles of unbleached flour cannot effectively hold the butter is suspension. So use bleached cake flour or bleached all-purpose flour.

Too Weak a Structure

This is usually due to too much leavening. Try dropping the baking powder by 1/4 teaspoon.

The larger the cake, the less amount of baking powder per cup of flour is used. This is because the distance from the sides of the pan to the center are greater so that they batter needs a stronger structure to support itself.

http://www.realbakingwithrose.com/questions_and_answers/faqs/#.VD5ersDD-71

 
Never mind. I think it means to decrease BP - I don't understand how it weakens the cake though.

 
I know this answer: It's in the Cake Bible.

I read this section over and over again when I was making LARGE cakes for my niece's wedding dessert table.

Bear with me, I'm going to paint a visual:
12" pan has a 6" diameter, so batter in the middle is 6" away from hot metal edges.
8" pan has a 4" diameter, so batter in the middle is 4" away from hot metal edges.

If the recipe is designed for an 8" pan, the amount of rising agent is perfect for creating air bubbles quickly--this will airily lift the batter structure, making it weaker until the protein sets with the aid of hot pan edges.

However, if you scale up the recipe--including scaling the rising agent--you get the same amount of fast air bubbles, but the middle of the batter is too far from the hot edges to help it set. That's why bakers will put a metal spike in the middle of large diameter cake pans.

Rose developed a math formula for slightly reducing the amount of rising agent by size so there are fewer air bubbles created, giving the protein structure more time to set.

Her two-layer 9" cakes fit perfectly in a single 12" pan, but apply the reduced rising agent.

Her single 9" cakes fit perfectly in two 6" pans, with NO need to reduce the rising agents (since the hot metal walls of pans are near enough to bake (set) the center of the cake,)

 
The *hot* pan edges are also the reason for using wet wraps around large pans.

The wet wraps keep the metal rims from getting too hot and baking the cakes edges quicker than the middle of the cake. They work beautifully.

Again, not necessary for standard cake pans, but the concept shines for half-sheet size cakes.

I've even taken heavy cardboard the WIDTH of the half-sheet cake pan, covered it with foil and divided the pan in two. Use 1 box cake mix for each side. Bakes perfectly.

 
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