Microorganisms: The secret behind many kitchen staples

Behind that soy sauce bottle, that serving of kimchi, and that tub of yogurt are microorganisms.

Fermentation has been used by humans for at least 10,000 years, primarily as a way to preserve foods and to improve their taste. It’s a natural process that is still used today to make a wide variety of food items including the aforementioned, as well as, unknown to many, monosodium glutamate or MSG.

It’s easy to confuse fermentation with food spoiling because the underlying mechanism is basically the same. To understand the difference, let’s take a look at milk. Naturally, if one lets milk sit in the refrigerator past its expiration date—or even worse, was not put in the refrigerator—the milk turns sour.

That’s a common example of spoiling. 

But, of course, milk can be turned into healthy, tasty food products such as cheese and yogurt. These are common examples of fermentation. Scientifically speaking, the cause of both spoiling and fermentation is the same: microorganisms

It wasn’t until the 1850s that scientists really understood the process. Before then, milk turning sour was thought to be a purely chemical reaction. In other words, scientists thought that two chemicals were interacting with each other to form a new product, which is what happens when iron rusts or when a match is lit. Yogurt and cheese had been made for centuries, but nobody truly understood why milk could be turned into these food products.

It was Louis Pasteur who demonstrated that living microorganisms—in milk, bacteria—caused the changes that occur in milk. This is also why milk is now pasteurized, a process whereby it is heated to eliminate bacteria and extend its shelf-life.

Today, fermentation is defined as a process by which microorganisms cause a beneficial change in an organic substrate. Yogurt and cheese are considered to be “fermented” not “spoiled,” because microorganisms are employed deliberately to create a beneficial change in the milk. Bacteria aren’t the only microorganisms used for fermentation. For example, yeast, which is not a bacteria, is used to ferment dough, giving us bread. 

Speaking of microorganisms, In 1909, Dr. Kikunae Ikeda, the inventor of AJI-NO-MOTO, isolated glutamic acid from kombu, which is a type of seaweed. He recognized that the taste of this substance was neither sweet, sour, salty, nor bitter, so he gave it a new name: umami. 

Dr. Ikeda’s discovery led to the development of MSG, which would bring umami to tables as a food seasoning.

But producing MSG on a large scale was challenging, which is a problem faced by many great discoveries. For years, MSG was produced through the “extraction method,” which uses wheat protein extracted from gluten. But this process was inefficient, difficult to perform on a large scale, and hard to reproduce reliably in factories outside of Japan.

Fortunately, in the 1960s, the bacteria responsible for creating glutamic acid was discovered, and fermentation became the primary production method of MSG. Importantly, this made it possible to produce MSG in Southeast Asia, South America, Europe, and North America.