Recipes engineered for perfection—what exactly does that mean? The Science series takes you inside the experiments behind 50 cooking concepts featured in our new book, The Science of Good Cooking, by the editors of Cook’s Illustrated.
Brownies. Some people like them cakelike and airy. I, however, am wholeheartedly in the rich and chewy camp. I like my brownies to be closer to fudge than cake. But when making fudgy brownies things can easily go seriously awry—even when following a recipe. The difference between fudgy and cakey brownies can come down to simply how much you stir the batter. Why?
It all comes down to gluten, the network of cross-linked wheat proteins that begins to form when water and flour are combined. In bread dough, this network is deliberately made to be strong, engulfing swollen starch granules and gas bubbles, stretching as the dough rises and then bakes to give the finished loaf its structure and chew. In quick-bread recipes like brownies, that’s exactly what we don’t want. The goal here is to minimize the development of gluten as much as possible. The addition of eggs, fats, and sugars to brownie batter has a tenderizing effect. These ingredients all interfere with the formation of gluten by slowing protein unfolding and bonding. But even with eggs, fats, and sugars in the batter, if you overmix a quick bread, you will end up with tough results.
Stirring would seem to be the gentle way of mixing the ingredients, but in a wet batter, it’s enough to begin unfolding the proteins and activate the formation of gluten. It really doesn’t take much gluten to turn a fudgy brownie into a disappointingly airy cakelike bar. This is why in the test kitchen we forgo the wooden spoon for a spatula and fold rather than stir. To avoid overmixing, wet and dry ingredients are carefully folded together until only a few streaks of dry flour remain.
To prove the importance of folding when it comes to my favorite kind of brownies, associate editor Dan Souza made three batches, varying only the mixing technique. For one batch he folded the wet and dry ingredients until they were just combined, with a few streaks of flour remaining.
For the second batch, he folded past this stage until no dry flour remained at all.
Finally, he mixed the third sample on low speed in a stand mixer with a whisk attachment for a full 5 minutes.
The results were dramatic.
While the properly folded batter baked into compact, tender, perfectly fudgy brownies…
…the overfolded sample was relatively cakey and tough.
Just that little bit of overmixing made a huge difference. And the sample whisked in the stand mixer?
No contest. This was the worst batch of fudgy brownies ever. They baked up almost twice as tall as the properly folded batch and offered serious resilience.
So if your goal is to make a batch of fudgelike brownies with some serious chew, pay close attention to your mixing technique. Fold—don’t stir. Use a spatula—not a wooden spoon. And make sure to leave streaks of flour behind.
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Our recipe for Triple-Chocolate Espresso Brownies is free through December 10, 2012.
Got any baking questions? Leave 'em in the comments.