Brewing 101: Zymurgy

Most people know that beer is fermented, and that fermenting is where the alcohol comes from. But what does that mean? In beer brewing, fermentation is the conversion of carbohydrates to alcohols and carbon dioxide using yeasts, bacteria or a combination of the two, under anaerobic conditions. More simply put, fermentation is the chemical conversion of sugars into ethanol. The science of fermentation is known as zymurgy.


It's so simple!

After the wort (young beer) is boiled, it is cooled and aerated, and then yeast is added to it, which begins the fermentation process. It is during this stage that sugars won from the malt are metabolized into alcohol and carbon dioxide, and the product can be called beer for the first time.

There are three main fermentation methods: warm, cool and wild. The first two, warm and cool, refer to the temperature at which the beer is fermented. Wild fermentation refers to the process of allowing wild, uncontrolled and untamed yeast to ferment your beer instead of specific, controlled, collected and deliberate yeast. There are different methods to deliver wild yeast, such as fermenting in a wooden barrel where yeast are already living or fermenting in open containers and allowing the natural wild yeast in the air have at the beer. These processes are more common in Belgium and other parts of Europe than they are in the States.

Wild yeast attacking some delightful beer

There are two types of brewing yeasts that are distinguished by where they ferment beer. The first type forms foam at the top of the wort during fermentation and is called top-fermenting yeast. Top fermenting yeasts generally produce higher alcohol concentrations and in higher temperatures (typically 61 F to 75 F) produce fruitier, sweeter beers.  The other type of yeast, bottom-fermenting, is typically used to produce cool fermented, lager-type beers. These yeasts ferment more sugars, creating a dryer beer, and grow well at low temperatures.

Here’s to craft-brewed happiness… Cheers!