Cooking Patterns > Food Processing Patterns

Fermentation

Fermentation is a biochemical technique for food processing. It breaks down sugars into other chemicals through the use of bacteria, yeast, or other living microorganisms.

The fermentation process works like this. A microorganism is mixed into a food substance that contains some form of sugar. The microorganisms then slowly eat the sugar, digest it, and poop out the desired chemical, along with some other by-products.

Fermentation is used to make several different types of food, including alcohol, bread, and yogurt to name a few. I cover these three food types here.

Alcohol

When creating alcoholic beverages, yeast is used to convert sugar into ethyl alcohol.

The different types of alcohol are made by using different sources of sugar. For example, barley is fermented to create beer and whisky, sugar cane is used to create rum. potatoes are used for vodka, and agave fruit is used for tequila.

Here is a demonstration of someone making homebrew beer with yeast:

Bread

In breadmaking, yeast is used during the proofing process to make the dough rise.

Before proofing, the dough is mixed and kneaded, creating millions of tiny air bubbles. The dough is then placed in a lit area to proof for a few hours. During the proofing (“poofing”) process, the yeast digests sugars in the flour, turning them into carbon dioxide. This gas then inflates the network of air bubbles, causing the dough to rise.

In most bread recipes, the dough rises twice. The first rise is the main one. Then the dough is formed into a loaf and left to rise again. Finally, it is put in the oven to bake.

You can see the many pockets of space that were created by the fermentation process when you cut a slice of the bread.

Here is a demonstration of someone making bread at home with yeast:

Yogurt

Yogurt is also made through the fermentation process.

Milk is first pasteurized by bringing it to a boil. This denatures the proteins in the milk. Denature means the bonds that hold the proteins in a folded shape break, causing the proteins to stretch out. The milk is then left to sit outside for an hour to come back down to room temperature. Then a small amount of yogurt, called the starter culture, is mixed into the denatured, room temperature milk. The starter culture contains the bacteria that are needed for fermentation. The bacteria eat the lactose sugar in the milk and poop out lactic acid. The acid causes the denatured protein in the pasteurized milk to coagulate or bond with each other. This results in the formation of the semi-solid, soft gel we know as yogurt.

Here is a demonstration of someone making yogurt at home with starter culture: