What Yeast does in the brewing process?

For most home brewers, selecting a recipe and ingredients is the most exciting part of the brewing process with the drinking part of the process being the reward. Although I do love the drinking part of the process, one of my favourite parts of brewing is still the fermentation of beer. What the yeast does in the brewing process is fascinating because of the natural science behind it. Fascinating because the greatest discovery in brewing beer took place around 4000 years ago when ancient Egyptians discovered that adding yeast to certain liquids created alcohol. And the world was changed forever for the better!

What is Yeast?

When brewers talk about the fermentation of beer, they are specifically talking about using yeast to convert the sugars in the beer into alcohol. For a lot of people, yeast is a mysterious substance that we use in brewing and baking without really understanding what it is. As gross as it sounds, yeast is a single celled creature that loves to feast on sugars. Yeast is actually a living organism. IT’S ALIVE! Because it alive, the temperature of the wort is vitally important to the success of the fermentation. If the wort is too hot, the yeast will die. If the opposite happens and the wort is too cold, the yeast will go dormant. Either situation means no beer! For ales, the ideal temperature is between 68-75 Fahrenheit, and for lagers, the ideal temperature is around 45 Fahrenheit.

Fermentation of beer

Once introduced to homebrew, yeast typically takes seven to ten days to convert all the glucose (sugar) in the wort into ethanol alcohol. The byproduct of this process is the production of carbon dioxide. Beer fermentation is basically the process that produces the alcohol and carbon dioxide content in beer. So to make this a bit easier to remember yeast is a living thing that eats sugar and expels alcohol and carbon dioxide!

Watch the show!

Once the yeast is added to the fermenter, the show really begins. The style of beer you are making, will dictate what type of fermentation you are going to have. Either you will have a calm quick fermentation that will create a bit of foam or you will have a crazy fermentation that will blow the top off your fermenter. I have personally brewed a double India pale ale recently that appeared to be boiling for two weeks straight without it being touched.
Once all the sugar is consumed by the yeast, the yeast falls to the bottom of the fermenter with the rest of the trub. When the beer is transferred to bottles or a keg, the yeast can be discarded. Keep in mind if you are using an expensive liquid yeast that you can actually wash it and use it in another batch of beer.

Like I said earlier, yeast fermentation is a fascinating process because of the natural science behind it. There are no added chemicals or laboratory procedures used to create beer. Yet in every sense fermentation is a science lesson!
The fermentation of beer is made naturally by a living thing known commonly as yeast. Yeast converts the sugars in the wort into ethanol alcohol to make beer. After fermentation is complete, your wort is officially beer and is nearly ready to drink. Cheers!

Photo by traviscrawford

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