Quick bread leavening agents include a weak base, such as baking soda (sodium bicarbonate) plus a weak acid, such as cream of tartar, lemon juice, or cultured buttermilk, to create an acid–base reaction that releases carbon dioxide. (Quick bread leavened specifically with baking soda is often called "soda bread".) Baking powder contains both an acid and a base in dry powdered form, and simply needs a liquid medium in which to react. Other alternative leavening agents are egg whites mechanically beaten to form stiff peaks, as in the case of many waffle recipes, or steam, in the case of cream puffs. Nevertheless,
Buttermilk cultured buttermilk to simulate residual flecks of butter that can be left over from the churning process of traditional buttermilk. Cultured buttermilk, often known simply as "buttermilk" now, was first commercially introduced in the United States in the 1920s. It was popular among immigrants, and viewed as a food that could slow aging. It reached peak annual sales of in 1960. Buttermilk's popularity has declined since then, despite an increasing population, and annual sales in 2012 reached less than half that number. Condensed buttermilk and dried buttermilk have increased in importance in the food industry. Buttermilk solids are used in