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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.
It seems simple: Add more sugar to a cookie dough and the cookies will be sweeter. Add brown sugar rather than white sugar, honey rather than molasses and you’ll change the flavor a bit. But that’s not all. Sugar does far more than add sweetness. It can change texture, too. But how?
It all comes down to moisture. Sugar is what we call hygroscopic, which means it has an affinity for water molecules. This means that sugar will hold on to moisture in food and can slow the evaporation of moisture from cookies and cakes as they bake. This makes a tremendous difference when it comes to producing moist, tender baked goods.
But not all sugars are created equal. Some have a greater tendency to hold moisture than others. After all, different sugars (brown versus white sugar, for example) have slightly different structures.
Sugar can be a single molecule made up of carbon, hydrogen, and oxygen—like glucose and fructose. Other sugars, like sucrose, or white table sugar, are made up of multiple molecules (in this case, one glucose and one fructose), tied together with chemical bonds. Now, when sucrose is heated with an acid, it breaks back down into the two smaller sugars, glucose and fructose, resulting in something we call invert sugar. This small chemical change makes a big difference: While sucrose is hygroscopic, invert sugar is even more water-loving.
And this can make a tremendous difference when, say, you want to bake a chewy, rather than crunchy, cookie. We hit the kitchen to get proof.
To show the powerful effect that sugar can have on the texture of a baked good, associate editor Dan Souza made two batches of chocolate-chunk oatmeal cookies, one with brown sugar and the other with granulated white sugar.
He kept the rest of the ingredients and the baking procedure identical.
After the cookies cooled to room temperature, we tasted them for chewiness and then Dan attempted to bend a sample of each batch around a large wooden rolling pin. (This is no easy task for the firm, crunchy cookies.)
The results were undeniable. The brown sugar cookies had some serious chew and bent around the curvature of the rolling pin with ease. The white sugar cookies, on the other hand, snapped in half immediately under pressure.
So you want a chewy—rather than crunchy—cookie? Look to sugar. Sweeteners that contain invert sugar, like brown sugar, help to retard the crystallization of sucrose, therefore holding on to more moisture than white sugar. And that will do a whole lot more than add sweetness.
MAKE IT NOW. Our recipe for Chocolate-Chunk Oatmeal Cookies is free through November 12, 2012.
Got some questions on sugar? Leave 'em in the comments.