As I explore the science behind baking I more and more aware of the role each ingredient has when creating the perfect cookie. I've been aware that sugar is more than a sweetner, it can also change the texture, taste, color and harness of a cookie. Rule of thumb, brown sugar has more mositure so it creates a chewier, softer cookie. White sugar has less and creates a thiner, crispier cookie.
But there is more. Much more...
When a recipe calls for creaming together the fat and sugar this is not simply a way of mixing these two ingredients together. The purpose of doing this step is to get air into the batter. This mixing causes the sugar granules to rub against the fat producing air bubbles in the fat. Later when the leavener is added, the leavening gases enlarge these air bubbles and cause the batter to rise when place in the oven. The length of time you cream the butter with the sugar determines the amount of air incorporated into the batter.
Sugar also attracts moisture in the batter which reduces the amount of gluten formed in the flour. The result of this is twofold. First, less gluten in the batter produces a baked good with a more tender crumb. Hence, recipes that contain a high sugar content produce a baked good with a more tender crumb Second, because not as much gluten is formed, the batter will be lighter. When baked, the batter will be able to rise more and the result will be a baked good with more volume.
The ability of sugar to hold moisture also prolongs the shelf life of baked goods. Liquid sugars hold more moisture than other types of sugars. Just as brown sugar will hold more moisture than granulated white sugar.
You may have wondered why batters brown in the oven. The browning is the result of the sugar reacting with the protein in other ingredients (eggs, milk) when heated. The higher the sugar content the darker the crust.
There are different types of sugar and the size of the granules can differ. Sugars vary in color from white to dark brown depending on the amount of molasses added during processing. The size of the sugar crystal affects the amount of air that can be incorporated into the batter during the creaming of the sugar and fat. For example, granulated sugar will incorporate more air into the batter than confectioner's sugar. The size of the crystal will also affect how quickly the sugar will dissolve in the batter. Therefore confectioner's sugar will dissolve quicker in the batter than granulated sugar.
White sugar is a refined sugar derived from sugar cane and sugar beets. It is sold in many granule sizes ranging from superfine to coarse.
Granulated white sugar or table sugar has fine to medium-sized granules and is the sugar most often used in recipes. Try to find one where the crystals are not too large as they do differ from manufacturer to manufacturer. When heated granulated white sugar takes on a toffee-like color and flavor.
Superfine (castor or caster) sugar is granulated white sugar that has superfine granules and is good for making meringues as it dissolves rapidly. You can make your own by processing granulated sugar in your food processor for a few seconds.
Coarse (decorators or pearl) sugar is granulated white sugar that has been processed into small, round grains that are larger than the grains of granulated sugar. They are typically used for garnishing baked goods.
Crystal sugar is like coarse sugar except the crystals are pellet shaped.
Confectioners, powdered or icing sugar is granulated sugar that has been ground to a powder with cornstarch added to prevent lumping and crystallization. It comes in 4X, 6X and 10X but 10X is the one generally found in stores. 10X means that the granulated sugar has been processed ten times. Confectioners sugar is used in meringues, icings, confections, and some sweet pastry.
Invert sugar is mainly used for commercial purposes and is produced by heating cane or beet sugar with a small amount of acid, such as tartaric acid. It comes in syrup form and is used in cake and candy making. Invert sugar gives baked goods: added sweetness and crust color, prolongs shelf-life, and when used in icings it produces added smoothness.
Brown sugar is a refined sugar that varies in color from light to dark brown and has a full-bodied flavor and soft moist texture. In the past brown sugar was semi-refined white sugar where some of the natural molasses was left in. Now brown sugar is made by adding molasses back into refined white sugar. The color will depend on the amount of molasses added during processing of the sugar. The darker the color the stronger the taste so use the one you like the best. The same weight of brown and white sugars has the same sweetness. Because white sugar is denser than brown sugar, to get equal sweetness firmly pack the brown sugar so when inverted the cup of brown sugar will hold its shape. Substituting brown sugar for white sugar in a recipe will produce a baked good that is a little moister with a slight butterscotch flavor.
Brown sugar has the tendency to lump and become hard. To avoid this, store in a glass jar or plastic bag in a cool dry place. If is becomes hard, soften it by placing a slice of apple in a plastic bag along with the brown sugar for a few days. You can also sprinkle a few drops of water on it and seal in plastic bag for a few days.
Raw Sugar is what is left after processing the sugar cane to remove the molasses and refine the white sugar. In North America raw sugar is actually not "raw" as it has been partially refined to remove any contaminants. The color is similar to light brown sugar but it's texture is grainier.
Demerara sugar is a raw sugar that has been purified. It comes from Guyana and is a dry, coarse-textured amber sugar that has a toffee-like flavor.
Muscovada or Barbados sugar is another raw sugar that has been purified. It has a finer grain that Demerara and very moist. Its color ranges from light to dark brown and it has a strong molasses taste.
Turbinado sugar is a raw sugar that has been steam cleaned. It is light brown in color and coarse grained, with a slight molasses flavor.
sugar info borrowed from The Joy of Baking
qoute from Chow Hound that proves me point about sugar:
"White sugar made a cripier, lighter colored cookie, Brown sugar made a denser, more moist cookie. However, the class favorites were those cookies made with a combination of the two!! "