Greek yogurt makes an excellent substitute for sour cream when baking cookies. A low-fat or fat-free version of thick, creamy Greek yogurt can take the place of higher-calorie sour cream in baking because it works the same way as sour cream in the baking process.
Baking Relies on Balance
Successful baking involves balancing two types of ingredients: strengtheners and tenderizers. Flour and eggs strengthen a baked good and give it substance. Fat and sugar tenderize it. Sometimes these functions can overlap, but it's still necessary to create balance among these ingredients to create the desired qualities of flavor, tenderness, moistness and texture in baked goods. That's where fats, such as butter, margarine, sour cream, heavy cream and yogurt, come in.
Fats Aid Chemical Processes
Fats perform several chemical functions in baking. In addition to tenderizing, fat aids in moisture retention. Fats also help to leaven causes cookie dough so that it rises properly. Butter, cream and yogurt also help create texture. Greek yogurt and sour cream are interchangeable because each can perform these functions in similar fashion.
Greek yogurt substitutes well for sour cream because their consistencies are similar. This means that when a cookie recipe calls for a cup of sour cream, a cup of Greek yogurt can be substituted without having to calculate an equivalent amount as with other kinds of fat. Another advantage to Greek yogurt is that it withstands heat better than sour cream, which can curdle in a recipe if the temperature is too high for it. Greek yogurt adds a more tart flavor than sour cream, which helps to balance the sweetness of cookie dough.
Be Sure of Yogurt's Quality
When replacing sour cream with Greek yogurt, check the product's authenticity and quality. Only yogurt that comes from Greece, where it's traditionally made with sheep's milk, can be labeled as Greek. Other strained yogurt is termed Greek-style yogurt; it should be thick and creamy like Greek yogurt. Greek-style yogurt can be an acceptable sour cream substitute, but be sure to read the product label to check for artificial thickeners such as starch or gelatin that may affect the cookie dough.
Plain Yogurt an Imperfect Substitute
Plain yogurt can't be substituted for sour cream with the same ease that Greek yogurt can. The regular version has more water than Greek yogurt, which can make cookie dough too liquid and retard leavening. Regular, or plain, yogurt can be strained to produce the same thick creamy consistency, but it also can have additives such as starch or gelatin to enhance its texture. These additives can ruin cookie dough by interfering with the chemical processes of both the strengthening and tenderizing ingredients. Swapping genuine Greek yogurt for the sour cream in a cookie recipe is much more likely to produce delicious results.