The last but not least, the yeast. If you are a new brewer you might be tempted to use regular yeast for baking. As your friend and guide through the brewing process I advise against it.
There is much to learn about yeast so lets begin. Yeast is the element responsible for the fermentation. Fermentation is the process where sugars/carbohydrates are converted to alcohol and CO2. Yeast also converts chemicals found in hops and changes the flavour and aroma of the finnished product.
The yeast you will use will greatly depend on the recipe and beer style, you intend to create. There are two main categories when it comes to beer yeast:
- top cropping yeast
- bottom cropping yeast
Top cropping yeast
In the more academic circles known as Saccharomyces Cerevisiae. As the name suggests, the yeast will make foam on the top of the fermented liquid. This type of yeast will be used when producing top fermented beverages. Some examples are IPA, APA and most of american beer :D. This kind of yeast prefers higher temperatures than the bottom cropping yeast (It is typical to see preffered temperature of fermentation around 15-20 °C/59- 68 °F). That is why a lot of homebrewers make top cropping beers.
When making top cropping beers one does not have to cool the fermentor as much as with bottom cropping yeast.
Bottom cropping yeast
In the more academic circles known as Saccharomyces pastorianus. We use this type of yeast to produce Bohemian, German and other laggers and some American styles of beers as well (certain ales). This yeast preffers low temperatures (all the way down to 5 °C/41 °F).
There are other ways to classify yeast as well, such as by the alcohol content they will tolerate or there are specific yeasts for certain brew styles as well as breweries having their own specially breed or modified yeast.