Fermentation Science

Fermentation is a natural process used by tiny organisms like yeast and bacteria. They eat sugar and produce other substances like carbon dioxide gas and alcohol. Humans have used fermentation for thousands of years to make bread, cheese, yogurt, and many other foods.

How Fermentation Works

Yeast and bacteria are microorganisms that break down sugar for energy. When they do this without oxygen, it is called fermentation. Yeast produces carbon dioxide gas and alcohol. The gas makes bread dough rise and creates bubbles in drinks. Bacteria produce lactic acid, which gives yogurt and sauerkraut their sour taste.

Fermentation in Food

Many foods you eat are made with fermentation. Bread rises because yeast produces carbon dioxide bubbles in the dough. Cheese and yogurt are made when bacteria ferment milk. Pickles are cucumbers fermented in salt water. Chocolate and coffee beans are also fermented as part of their processing.

Fun Facts

• Humans have been using fermentation to make bread for over 5,000 years.
• The holes in Swiss cheese are made by carbon dioxide gas produced during fermentation.
• Sourdough bread uses wild yeast and bacteria from the air for fermentation.

Did You Know?

Your muscles use a form of fermentation when you exercise really hard. When your muscles cannot get enough oxygen, they ferment sugar to produce energy. This produces lactic acid, which is what makes your muscles feel sore!