Tapping the Power of Brewers Yeast

I think people that don’t make beer would be shocked to know what a beautiful complex process it is. There are five things that go into a beer. Water, malt, hops, the yeast, and then finally you have the brewer managing all that. Because the same brewer can take all those four ingredients and depend on the temperatures and timing of each step he can make a completely different beer.

If you want more information on yeast in the beer brewing process be sure to check our Beer School: What is Yeast.

The oldest Yeast

Pouring dry yeast from a bottle to a bowl.
Credit: https://www.purewow.com/food/instant-vs-active-dry-yeast

Yeast created ethanol that’s present in beer and distilled spirits. A lot of people think brewers make beer. But they don’t. Yeast makes beer. Brewer’s yeast is probably the oldest domesticated organism and human beings have been capturing and propagating it for different purposes for thousands of years.

In 1990, brewers yeast, saccharomyces cerevisiae was the first eukaryotic genome to be sequenced. It was a really important advancement in science. Much of what we know about human health comes from the study of model organisms. brewers yeast is a single cell so it’s easier to study. It’s easier to manipulate the genes.

The Brewing Process

So the process of brewing starts by grinding them all. We need to extract the sugar and the protein from it. The malt is usually barley or wheat. It has to be grown to the right stage, germinated until the sugar starts to break down. And then the germination has to be stopped by heat.

Wheat plants in different stages of growth.
Credit: https://www.dreamstime.com/photos-images/germinated-wheat-seed.html

The longer you heat the grain, the darker the malt gets. Darker malts have tastes of chocolate and coffee. Lighter malts are more acidic.

It goes into a mash tun where it’s heated in the presence of water. As the water is heated enzymes in the malt are activated. That actually breaks down more complex sugars and proteins. After that stage, the extract from the malt is drained into a kettle and boiled in the presence of hops.

Hops are bred for a huge variety of flavors, aromas, and bitterness. They are added at different stages during the brewing process to have different effects.

Louis Pasteur

Photograph of Louis Pasteur the French scientist.
Credit: https://www.indiatoday.in/education-today/gk-current-affairs/story/louis-pasteur-1351743-2018-09-28

One of the earliest contributions that brewer’s yeast made to human health happened sometime about 120 years ago. A lot of prominent scientists were interested in the nature of fermentation. One of them was French scientist Louis Pasteur. He realized that when the wine and beer tasted correct there was only one microorganism present under the microscope. And it was yeast.

When it tasted poorly, sour or other off flavors he was noticing all kinds of smaller microorganisms. He was able to formulate the theory that there were actually small microorganisms in the environment, our food, water, and air that were making people sick. If you just boiled or superheated food or water you could sanitize it to the point where it would no longer make people sick. The process of sanitizing solutions by boiling is now named pasteurization after him.

Back to Brewing

Once the wort is boiled in the kettle is finished it has to be cooled off. Usually through a heat exchanger piped to a fermenter. And that’s when the yeast is pitched. We cultivate yeast by storing them first at -80 C. From there they’re thawed and streaked onto plates where we pick single colonies. Then they are grown up in liquid media in larger and larger phases. From there they are pitched into our propagation tanks where they are grown on a larger scale.

Five glasses of beer with different type of beer in each one.
Credit: https://www.minnpost.com/second-opinion/2018/04/study-links-drinking-more-5-glasses-wine-or-beer-week-lower-life-expectancy/

When the fermentation is completed most beers are then transferred to a conditioning tank. People have been making beer for a long time. Thousands of years and essentials of making beer haven’t changed. There’s really no alcoholic beverage that’s created without yeast. Or very few. You can’t overestimate its contribution to public health. Yeast is an important part of beer and science. Cheers.

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