National Sourdough Bread Day Date in the current year: April 1, 2024

Bread has been a staple in many cultures around the world throughout recorded history. Early breads were unleavened; it is believed that the first leavened bread was baked by the Sumerians around 6000 BC.

Leavening is a process that causes carbon dioxide bubbles to form in doughs and batters, making bread and other baked foods rise in the oven and giving them a soft and airy texture. Bread may be leavened by naturally occurring bacteria and fungi, industrially produced yeast, chemicals, steam, or aeration.

The dough used to make sourdough bread is fermented using naturally occurring lactic acid bacteria and yeast. Lactic acid produced during fermentation gives sourdough bread its characteristic mildly sour taste, which has given it its name. Rye bread is usually leavened with sourdough because it contains too little gluten to be leavened with baker’s yeast.

According to food historians, bakers have relied on the use of sourdough as a leavener for most of human history. To make sourdough breads, bakers use the so-called sourdough starter. It is a mixture of flour and water that contains a colony of wild lactobacilli and yeast. These microorganisms are naturally present in flour, but they need water, time and the right temperature to grow and develop a stable culture.

Back in the day, European peasants would bake sourdough bread once a week, saving a piece of dough to use as the starter the next week. Sourdough techniques were brought to the New World by French bakers during the California Gold Rush and spread to Alaska and Yukon during the Klondike Gold Rush thanks to California miners who made their way north, bringing along their sourdough starters.

Some of the best known sourdough breads from different parts of the world include Amish friendship bread (United States), bazlama (Turkey), borodinskiy bread (Russia), coppia ferrarese (Italy), eish merahrah and eish shamsi (Egypt), injera (Ethiopia and Eritrea), pumpernickel (Germany), rugbrød (Denmark), and others.

In the 20th century, sourdough was gradually replaced by cultured yeasts in most commercial bakeries. However, sourdough baking has a devoted community of artisan bakers and baking enthusiasts. They exchange starters and tips online and share their work on social media. Some sourdough baking enthusiasts even name their starters and intend to pass them on to their heirs (there are starters that have been passed through several generations of one family).

If you’re a fan of sourdough bread, don’t forget to celebrate National Sourdough Bread Day on April 1. It is the perfect occasion to make your own sourdough starter, take a trip to San Francisco, which has been synonymous with sourdough bread since the California Gold Rush, or buy a loaf of sourdough bread at your local bakery if you’re not feeling particularly adventurous.