Monday, June 2, 2008

Why did the chocolate shortbread turn out so weird?

It is flaky when it is supposed to be crumbly!

Some of you may have sampled my chocolate "shortbread", and you probably noticed that it had several problems. First, it was bland, but the most severe failure was the texture. Shortbread is supposed to be crumbly and buttery. Mine was flaky with layers. The crumbliness is due to lack of gluten formation in its dough.

Gluten is a protein that forms in wheat flour when the already resident proteins gliadin and glutenin come in contact with water. When mixed or kneaded, this long and sprawling protein will form bonds with itself and other gluten molecules, creating an elastic web. This web is useful in cakes and breads because it enables the batter/dough to retain the carbon dioxide produced by yeast or chemical leaveners. Without gluten, it would be impossible for these to rise.

Shortbread is a different story. It is not meant to rise, and contains no leaveners. It is crumbly because there is no web of gluten to hold it together. The basic shortbread recipe is: mix butter with flour and sugar. Knead to form a ball. Roll out and bake. Notice there is no water to allow gluten to form.
Well, I had never made shortbread before, and in fact I didn't even know what shortbread was supposed to be like. So I followed a recipe in my favorite cookbook. The recipe told me to use "very cold butter", so I did. Unfortunately the butter was so cold that the dough refused to form a cohesive ball. I was confused, and I decided to add some water and see what would happen. Well, as you can guess, it was turned out like a thick cracker than anything else.
Later, I looked up shortbread recipes online and found that they all used almost twice the amount of butter mine had, and they did specify for the butter to be cold.

This was the most I could get out of cold butter. It is still powdery.

Information came from On Food and Cooking by Harold McGee, and Wikipedia

1 comment:

Julien said...

Very nice explanation. Good research.