sourdough

Everyday

1. Sourdough is bread made with a starter, a mix of flour and water full of wild yeast and bacteria, instead of packet yeast; it tastes slightly sour. tree →
2. A sourdough starter is the bubbly mixture kept alive and «fed» with flour and water to make this bread. tree →
3. (US, old) A sourdough was an old-timer in Alaska or the Yukon, especially a gold prospector. tree →

In the lessons

In science lessons it shows microbes at work: the yeast makes carbon dioxide gas, which makes bread rise, and the bacteria make acid, which gives the sour taste. In everyday life many families bake sourdough at home. Phrases: «a sourdough loaf», «sourdough starter», «feed the starter».

Examples

• We had sourdough toast for breakfast. tree →
• Our sourdough starter bubbles because of the wild yeast. tree →
• Feed the starter with flour and water every day. tree →
• Sourdough tastes a bit sour because of the bacteria. tree →
• The bakery sells a crusty sourdough loaf. tree →
• Gas bubbles from the yeast make holes in sourdough. tree →
• San Francisco is famous for its sourdough. tree →

Note

Uncountable as bread (some sourdough), countable as loaves (two sourdoughs). It is one word. The sour taste is from lactic acid, the same acid as in yogurt.