Food for Today

Food Science Activities :

Cookie Chemistry

Have you ever wondered why some cookies come out thin and crunchy, while others are fat and fluffy, yet still others are soft and chewy? A cookie’s texture largely depends on how much the dough spreads before the structure sets during baking. These processes, in turn, are affected by the choice of ingredients and how they interact. Understanding these relationships can help you predict the outcome. Recall, however, that recipes for baked items are actually complex systems. The presence or lack of an ingredient doesn’t guarantee a certain texture, but understanding how ingredients work can help guide you in choosing a recipe that gives the texture you want.

Thin and Crunchy
The more a cookie dough spreads during baking, the thinner and crunchier the finished product will be. What ingredients promote spreading over setting? For the fat, margarine and butter are better choices than shortening. Due to their chemical makeup, they start to melt at lower temperatures than shortening. They also contain a little water.

Sugar too plays a leading role. A high sugar content increases spread because the sugar liquefies at baking temperatures. In fact, it is sometimes considered a liquid ingredient.

Recipes that use granulated sugar are most likely to retain a crisp texture. Sugar is hygroscopic (hy-gruh-SKAH-pik). That is, it readily takes up water. Granulated sugar, however, is less hygroscopic than other common sweeteners, so granulated leaves more water in the mix.

Sugar also raises the temperature at which proteins coagulate, which delays setting. Likewise, baking soda raises the setting temperature by neutralizing some of the recipe’s acidity.

Fat and Fluffy
Cookies with a cakelike texture may start with cake flour. This low-protein flour ties up less water in forming gluten. Water escapes as steam, raising the dough. Reduced amounts of fat and sugar speed the rate of coagulation and setting. Vegetable shortening in the ingredients list also suggests a quick set and fluffier texture. Any solid fat will spread more slowly if the formed cookies are chilled on the pan before baking.

Recipes that use more eggs, with their superb binding and coagulating properties, are also apt to spread less and rise more. Eggs provide some of the water that rises as steam. Egg whites have a drying effect that further promotes a light and airy interior. Finally, baking powder increases acidity, which quickens coagulation.

Soft and Chewy
A chewy texture depends on moistness plus density. Vegetable oils and melted fats, which don’t trap air as well as solid fats, contribute to both qualities. Among sweeteners, look for brown sugar, honey, molasses, and corn syrup. They are hygroscopic, absorbing water from the air even after baking. Powdered sugar, with its fine texture, also makes for a dense texture.

Extra egg yolks add fat and richness. Lesser amounts of leaveners decrease rising. Bread flour, while not often used in cookies, also helps create chewiness. Small amounts of bread flour add the protein and gluten needed for a more compact cookie.

Make It Your Way
With all of this information in mind, you’re better equipped to choose recipes for the cookies that are most appealing to you—or to a family member or special friend. You might even be inspired to take a cookie recipe from the family files and experiment to make it your way.


Ingredients are a good clue to a cookie’s texture because they affect the
A)cookie’s color.
B)rates of spreading and setting.
C)oven temperature.
D)baking time.

Margarine’s chemical makeup makes it a good choice for crispy cookies because it
A)melts at relatively low temperatures.
B)is less likely to burn than butter.
C)adds less air than vegetable oils.
D)reduces acidity.

An important quality in sugar related to texture is
A)promoting browning.
B)providing protein.
C)retaining moisture.
D)none of the above.

Hygroscopic ingredients affect texture by
A)incorporating air.
B)limiting gluten development.
C)attracting water.
D)liquefying sugars.

Compared to a crunchy cookie, a cakelike cookie is apt to have
A)more eggs.
B)more liquid.
C)more fat.
D)more sugar

Chilling cookie dough affects texture by
A)allowing water to escape.
B)slowing the spread of solid fats.
C)reducing coagulation.
D)deactivating leaveners.

Cookies that use more egg whites than yolks are most likely to be
A)fluffy and cakelike.
B)moist and chewy.
C)moist and chewy.
D)none of the above.

Both eggs and baking powder have the effect of
A)lowering the melting temperature of fats.
B)releasing water.
C)trapping water.
D)adding structure

To achieve the textural results created by vegetable oils, look for recipes that use
A)cake flour.
B)extra egg whites.
C)small amounts of sugar.
D)melted margarine or butter.

To help ensure that a cookie stays moist after baking, choose a recipe that uses
A)bread flour.
B)vegetable shortening.
D)fewer eggs.

Suppose you have a recipe for a fluffy cookie that calls for margarine or butter, but you have only vegetable oil. What difference might you expect in the texture if you use the oil? Why? What changes in other ingredients might you try to lessen the difference?
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