Fermentation

Ever wonder about the science behind some of your favorite foods like yogurt, pickles, kimchi, kombucha, and bread? Well, all of these delicious foods are thanks to a process called fermentation!

A Quick Historical Overview

Fermentation has been around for thousands of years, dating back to as early as 7000 BCE. From ancient Egypt to China, this process spanned worldwide, and continues to play a prominent role in food culture today. The science behind fermentation only came to light when the French microbiologist and chemist, Louis Pasteur, demonstrated that this process occurs due to living microorganisms like fungi and bacteria. Another scientist, named Eduard Buechner, built upon Pasteur’s work and was able to extract the enzymes from microorganisms that hold the ability to break down sugars.

What Exactly is the Fermentation Process?

Many organisms require oxygen to perform cellular respiration. Things like glucose and oxygen are used to make ATP, the key to providing enough energy to vital cellular processes. There are times where some organisms need to make ATP for cellular processes without oxygen. Certain microorganisms like bacteria, fungi, and muscle cells have developed processes, like fermentation, to provide energy for cellular processes in the absence of oxygen. It is an anaerobic process, or a process in the absence of oxygen, that breaks down carbohydrates into acids or alcohols through the action of enzymes from microorganisms. This means that these microorganisms can continue glycolysis, a process that breaks down glucose in order to release energy.

There are two main types of fermentation, alcoholic and lactic acid fermentation. In alcoholic fermentation, yeast break down glucose into ethanol, carbon dioxide and ATP products. Common in muscle tissue, lactic acid fermentation is where glucose is converted into lactic acid and cellular energy in the form of ATP products. This occurs by the presence of the lactate enzyme, lactate dehydrogenase.

How Fermentation is Used in Foods

In food fermentation, carbohydrates are converted either into alcohols, acids or carbon dioxide. This process transforms foods, often changing a food’s smell, taste or texture. For example, lactic acid fermentation is used to pickle vegetables. Foods like sauerkraut and pickles are submerged in acid or salt brines and stored in an air sealed container to remove the presence of oxygen. This anaerobic environment is ideal for producing lactic acid producing bacteria that break down the natural carbohydrates of the vegetable and produce preserved foods with different flavor profiles, while reducing the presence of bad bacteria, which greatly improves many foods’ shelf life.