Why baking baking soda changes its use in the kitchen
When baked, baking soda turns into sodium carbonate, a much stronger base, with its own uses in bread, noodles, and pretzels.
Baking soda has many uses beyond baking. In Chinese cuisine, it's used to tenderize meat, and at home, it's used as a household cleaner, for example, to remove labels from glassware. When used in baking, however, it takes on a whole new range of applications.
When baking soda is exposed to oven heat, it transforms into sodium carbonate, also known as soda ash. Both are closely related, but their distinct chemical formulas give them different properties. Sodium carbonate is not used as a leavening agent in baking; it is primarily used to flavor, soften, and give a pleasant texture to breads and pasta.
To achieve this, spread an even layer of baking soda on a rimmed baking sheet and place it in a preheated oven at 250-350 degrees Fahrenheit. During baking, the baking soda releases water vapor and carbon dioxide, losing approximately one-third of its weight. The time varies considerably depending on the oven, ranging from one to five hours. To monitor the process, weigh the empty baking sheet and then the baking soda, checking it every half hour until it has lost one-third of its weight.
The loss of these components transforms bicarbonate into carbonate and drastically changes its pH. Sodium bicarbonate is a mild base, with a pH of 8.3, while carbonate is a strong base, with a pH of 11.3. In other words, carbonate is 1000 times more alkaline, which makes a huge difference in cooking.
Sodium carbonate is perhaps most popular in Chinese and Japanese cuisines, where it gives noodles an elastic texture. It compacts the gluten networks and creates the chewy texture of traditional ramen noodles. In Chinese cooking, bicarbonate is also added to fermented bread dough to balance its acidity.
Sodium carbonate is also used as a substitute for lye in some recipes. Lye is primarily associated with soft, German-style pretzels, to which it imparts their flavor and dark brown color, but it is caustic, dangerous to handle, and difficult to find in stores. Many recipes substitute it with bicarbonate of soda, with a different result; sodium carbonate comes much closer to the flavor and texture of lye-soaked pretzels.
