104 Principles of Food Science Baking Batters and doughs used to prepare baked goods are complex food mixtures. Understanding the effects of pH on these mixtures can help a baker be more successful. The freshness and pH of ingredients will affect the flavor, color, and texture of finished products. Chemical Leavening Agents Chemical leavening agents are ingredients that are added to baked goods to lighten or aerate the finished product. Baking powder and baking soda are the chemical leavening agents used to make many baked goods light and fluffy, 6-12. These leaveners work because they contain a base. When they are combined with an acid and moistened in batter or dough, neutralization occurs. The by-products of the neutralization process are a salt, water, and carbon dioxide gas. The carbon dioxide becomes trapped in the batter or dough and creates air pockets. The air pockets swell and form a light, porous structure during baking. Baking Soda Baking soda, or sodium bicarbonate, is a salt. It is formed by combining sodium hydroxide (NaOH), a strong base, and carbonic acid (H 2 CO 3 ), a weak acid. Sodium bicarbonate is a base. When baking soda and an acid are combined in a baked product, carbon dioxide is released. Acids commonly used with baking soda include lemon juice, vinegar, sour cream, buttermilk, and cream of tartar (tartaric acid). Buttermilk and yogurt have a naturally low pH. If stored properly, these and other low pH foods will generally stay fresh for long periods. However, even foods with low pH may be spoiled by the actions of some microorganisms. Yeasts can grow in a range of pH 4 to 7. They play a role in the making of wines and breads. Molds will grow in a wide range of pH from 2 to 8.5. Mold and pH monitoring are a part of the processing of tea, coffee, chocolate, cheese, and shelf- stable juices. Salts are a by-product of neutralization. They help preserve foods. They work by killing bacteria through dehydration. Salt is abundant, inexpensive, and works without refrigeration or special canning. As a result, packing in salt was a common preservation method for pioneers in colonial America. Settlers in the United States often salt cured hams, bacon, and other pork products. Vizual Studio/Shutterstock.com 6-12 Biscuits are usually leavened with baking powder. JBryson/iStock/Getty Images Plus 6-11 Low-acid vegetables, which have a pH of 4.6 or higher, must be pressure canned to ensure their safety. Copyright Goodheart-Willcox Co., Inc.