Beer 101: Yeast

Yeast is one of the four main ingredients that go into making beer, beautiful beer. The others are hops, malt, and water (this post is next in my Beer 101 series). There are certainly other ingredients that can be added to the beer process, but these four are the core pillars that hold up the whole thing.

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These itty bitty single-celled microrganisms are technically classified as a fungi. They reproduce by an asymmetric division process called budding. Their job is to convert fermentable sugars from the malt into alcohol and other byproducts. There are hundreds of varieties and strains of yeast out there, some of which are commonly used to brew beer.

Yeasts are generally put into one of two categories: ale yeast (top fermenting) or lager yeast (bottom fermenting), depending on how they behave during the fermentation process. There’s also a nebulous third category, known as spontaneously fermenting yeasts, which result when beer is left exposed to the air and is literally infected with wild yeast strains as they wander by – this is what creates sour beers.

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Ale yeasts generally sit on top of the beer-to-be, fermenting away between temperatures of 10° to 25°C (though some yeasts won’t activate below 12°C). These guys rise up to the surface, forming a thick raft of a head as they bubble away. These yeasts tend to yield beers higher in esters, which are the chemicals that give fruits their characteristic flavors. In the case of Hefe Weizen beers, the yeast produces the ester iso-amyl acetate, the same one that is found in bananas. Other esters include ethyl acetate, which can be flowery, and ethyl caproate, which is kind of wine-like and fruity. Top-fermenting yeasts are used for brewing ales, porters, stouts, Kölsch, Altbier, and wheat beers.

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Lager yeasts create much less of a head and tend to settle at the bottom of the tank as fermentation nears completion. They grow less rapidly than the ale yeasts and don’t create that layer of thick foam on top of the beer. These yeasts work at lower temperatures, around 7° to 15°C.

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In addition to making beer the alcoholic beverage that we so enjoy, it also has a large impact on the flavor of the final beer. The flavor and aroma of beer is complex and is influenced by  many factors, including malt, hops, and the yeast strain. The synthesis of yeast creates many byproducts, including ethanol (alcohol), CO2 (carbon dioxide), and also some flavor compounds like clove, butterscotch, and green apple.

Yeast may be tiny and invisible to the naked eye, but it plays a huge role in making beer what it is.

 

 

Review: Firestone Walker Union Jack IPA

This Union Jack IPA is described as a double dry hopped India pale ale and let me tell you, it is pretty aggressive! I wouldn’t call it a palate destroyer exactly, but it has punch to it.

If I’m remembering my early beer drinking days correctly (and they involved plenty of beer, so maybe I’m not, to be fair), this IPA by California brewery Firestone Walker might have been one of my first IPA experiences. At that time, I was still pretty new to beer in general and tended to prefer roasty, dark stouts so an IPA was a pretty big long shot. I would bet that I didn’t like it very much. It’s no wonder it might have scared me off of the style, considering its big, bold hops flavors.

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I decided to give it another go now that I’m older, wiser, and very much into IPAs. I poured this from a bottle into a Sam Adams Perfect Pint Glass. This is one of my favorite ways to enjoy a beer! These glasses have a laser-etched bottom inside, which generates activation sites for the CO2 bubbles in beer to form up. These bubbles are part of what delivers the flavors of beer to us, as well as what creates the experience of carbonation. Sadly, I did not get these glasses in the divorce. Dang!

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This beer poured a rich golden yellow with a significant head that stays for days. There’s a very green, grassy nose that’s hoppy as well. It’s maybe even a little bit bready, too. The taste is all hops! Hops, hops, hops! It never got too dry, though, and there was maybe just a hint of citrus on the back end. It’s odd, but I’d even say that this beer gets a little sweeter as it warms up. Very strong hops flavor, but a very drinkable beer to be sure.