While there are literally hundreds if not thousands of different classifications for beer, they all come from one of two starting points. You either have an Ale or Lager. As a general rule, most macrobrews are lagers while microbrews are ales. We will get into why that is in just a bit.
So what is yeast?
Yeast is a single cell organism that eats sugar. When it eats (ferments) sugar it gives off three by-products; carbon dioxide (CO2), alcohol, and heat. This is why we use it for brewing, without yeast, we would have a grainy, sugary drink that didn’t make us feel very good (or as good as a drink with alcohol can).
Ale vs. Lager
As I said before, everything boils down to the type of yeast you use; lager or ale. An ale refers to a yeast that ferments on the top of the fermenter and will function from 60-76 degrees or so. If it gets any colder than 55 degrees, the yeast will go dormant and stop fermenting. Ales can ferment in 3-7 days depending on the sugar available. Generally ale yeast give you a higher alcohol concentration. Ales also give off a fruity ester flavor that is desirable for some types of beer.
A lager on the other hand is a bottom fermenting yeast and functions at colder temperatures (40-55 degrees). It tends to give a crisper beer, but also takes longer to complete. It can take as long as month and a half. Lagers are much lighter in body and tend to be harder to make. A lager does not give off the esters of an ale, and therefore, it can be easier to detect when something goes wrong.
My choices for homebrew
Luckily homebrew shops offer a huge variety of yeast. Some cultures are specially made to give special tastes. A hefeweizen yeast will often give a bananna flavor to the beer. The yeast also come in several different forms. The first is dry yeast. Dry yeast is freeze-dried yeast cells that are very cheap. You must rehydrate the yeast in order to give it a proper chance at life. Another problem is that it can become easily infected and cannot be used on multiple batches.
The other option is liquid yeast. These generally come in two forms, The first is a smack pack. There is a bag within the outer bag that hold yeast nutrient. When you smack the bag, you release the nutrient and the yeast start feeding and multiplying. It is an effective means of generating healthy yeast growth.
The other liquid yeast can be found in vials (pictured at the beginning of this article). It is basically a vial of dormant yeast cells that need to be grown a bit to get proper pitching rates. Liquid yeast is the way to go if you want to make several beers using the same type of yeast. It is reusable. The only real downside is the upfront cost. Dry yeast can be found for around a dollar, where liquid yeasts cost at least $6. But you get a better pitching rate and it can be used over and over again.
I’ll explain what I mean by some of these terms more indepth next week.