Two Ways to Make Dough Rise
Baked goods rise when gas gets trapped in a batter or dough and expands in the heat of the oven. The gas can come from living yeast, which produces carbon dioxide as it feeds on sugars, or from a chemical reaction, typically between an acid and an alkali. Both approaches have long histories, and they solved different problems.
Fermentation First
For most of history, leavened bread depended on fermentation. A baker might keep back a piece of dough from the last batch, or maintain a sourdough culture, a mix of wild yeasts and bacteria that sours and lifts the dough. In many regions bakers also collected foam from brewing, called barm, and added it to dough. Brewing and baking were closely linked for this reason.
These methods worked, but they were slow and variable. A culture could weaken in cold weather, and a loaf might take many hours to rise. Home bakers needed time, experience and a source of active culture.
Yeast Becomes a Product
In the nineteenth century, scientists including Louis Pasteur showed that yeast is a living organism responsible for fermentation, part of a wider discovery of microscopic life at work in food. That knowledge helped producers grow yeast deliberately rather than relying on brewery leftovers. Compressed yeast, sold as moist cakes, appeared in Europe in the middle of the century and soon reached the United States, where the Fleischmann family is often credited with popularizing it from about the late 1860s.
Compressed yeast was more predictable than barm but did not keep long without cool storage, a problem eased once household refrigerators became common. Dry yeast formulations came later, and active dry yeast became widely used in the twentieth century, with military supply needs during the Second World War often cited as a spur. Instant forms followed. Each step reduced the skill and time required to get a reliable rise, which is part of why store-bought bread and home baking could coexist.
Chemical Leavening Arrives
Chemical leavening offered something yeast could not: speed. In eighteenth-century North America, bakers experimented with pearlash, a potash made from wood ashes, which reacts with acids such as sour milk to release gas. A recipe using it appears in an American cookbook of 1796, often cited as an early example, though the practice may be somewhat older.
In the 1840s sodium bicarbonate, known as baking soda or saleratus in some places, became more widely available. It releases gas when combined with an acid such as buttermilk, molasses, vinegar or lemon juice. This made quick breads, biscuits, pancakes and cakes possible without waiting for fermentation. The weakness was balance: too little acid left a soapy taste, and too much changed flavor.
Baking Powder
Baking powder, a product of the growing chemical trade and early industrial chemistry, packages the alkali and a dry acid together, with starch to keep them stable. Add liquid and the reaction begins. The Englishman Alfred Bird is often credited with an early version in the 1840s, said to have been made for a family member who could not eat yeast breads, though the details of the story vary between tellings. In the United States the chemist Eben Horsford developed phosphate-based powders in the mid-nineteenth century, and commercial manufacturers soon competed.
Later formulations used acids that react at different stages. Some release gas when mixed with liquid and more when heated in the oven, so that a batter does not have to go straight into the oven. Different acids produce different aftertastes, and aluminum-based ingredients became a topic of consumer debate, so some products are now marketed without them.
What Changed for Home Cooks
Reliable leaveners changed the daily kitchen in several ways.
- Cakes and biscuits could be made in under an hour, supporting a wider range of home baking.
- Recipes became more precise, because measured leaveners behave consistently.
- Cookbooks and packaged-food advertising spread standard recipes, a development that went hand in hand with the growth of convenience foods.
- Factory-made bread and mixes used the same chemistry at larger scale.
How They Compare
Yeast gives bread its characteristic flavor and structure but needs time. Baking powder and soda give a tender, quick result with a different crumb. Many recipes now use both, or add a little baking soda to sourdough pancakes for lift. Neither technology replaced the other, which is a common pattern in the history of kitchen tools: new methods tend to sit beside old ones.