Greetings everyone! Thank you for being so patient in waiting for this latest segment in your continuing Beerducation. Today we bring you yeast, the mighty little microbes that convert all that sugar into alcohol. They are the amazing alchemists that make beer, beer.
Yeast is a microscopic fungus that has been one of humanity’s best little helpers for thousands of years, helping us ferment beverages and make bread for millennia. For beer there are primarily two strains of yeast used and choosing the proper type is a huge factor in determining what kind of beer you will come out with, but more on that later. Depending on the type of yeast you use, you can come up with a variety of flavors and aromas such as banana, clove, plums, prunes, clove, and vanilla; even tartness and sourness.
To briefly recap some of our previous lessons, once the sugars are extracted from the grain, making wort, the liquid is boiled and hops are added at this time. Once the boil is finished (after 60 to 90 minutes usually) the wort is then crash cooled as quickly as possible. Once the wort reaches the target temperature you want to ferment the beer at the yeast is added and the fermentation vessel is sealed with an airlock. As the yeast consumes the sugars and produces the alcohol it will also produce plenty of carbon dioxide, which will need to escape.
How do you determine your fermentation temperature you ask? Well that factors in when choosing your yeast. The two main ones are the warm fermenting ale yeast, and the cool fermenting lager yeast.
Ale yeast is by far the oldest, dating back to when dinosaurs ruled the earth (http://www.fossilfuelsbrewingco.com/)! Aside from our reptilian cousins, humanity has also been using this yeast for centuries. Ale yeast usually ferments at temperatures within the 65-75 degree range at a faster rate. The result is a less “clean” beer with more prominent fruity flavors (known as esters) that give ales an added complexity. Common ale styles are the Pale Ale, the Heffeweizen (wheat beer), and Stouts.
Lager yeast is the new kid on the block at roughly several hundred years old. It is believed to have been originally developed somewhere in Germany through the practice of storing and aging beer in caves. The word lager means “to store” in German. Lager yeast is usually fermented in the 45-55 degree range in a slower, less tumultuous process. After the initial fermentation the beer is stored at near freezing temperatures for an additional period (the actual lagering). This process integrates sulfur compounds that come from lager yeasts, giving lagers their crisp, clean taste. Common examples of this are the Pilsner, Oktoberfest and the mighty Dopplebock.
Right now I’m going to clear up a common myth about ales and lagers; that ales are darker beers with higher alcohol and lagers are always lighter beers with lower alcohol. This is completely and utterly false. Ales can be made as light as any lager and low in ABV with the English Bitters as an example, being pale straw and in the 3-4% ABV range, and lagers can be be dark and mighty, with Baltic Porters being as dark as any stout with up to 10% alcohol.
There is one other variety that I haven’t touched upon and that is yeast from wild, or open fermentation. Used in parts of Belgium to produce Lambic beers, the process calls for native yeast spores to inhabit open vats of wort for fermentation. Once fermentation is completed, it is aged in wooden barrels and often mixed with other beers. The result is a wild and unique sour beer, although some styles are mixed with fruits to sweeten them. While I recommend everyone to try a lambic at some point, I’d be careful about trying open fermentation yourself. While the wild yeast in Belgium may be world class, you’re probably not going to get the same results in Brooklyn.
Thanks for tuning in for your continuing Beerducation, I hope you enjoyed reading it as much as I enjoyed writing it (which, in case you’re wondering, I did very much enjoy it). Keep an eye out for the next segment where we’ll begin delving into some beer styles and also a recap of our next adventure in home brewing, where we will be making an American Amber Ale and a French Saison. Until then enjoy the nice weather, stay safe, be healthy, and enjoy some great beer!
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