As I mentioned in the last blog, yeast plays a fundamental role in beer.  Let’s expand on that idea just a little more.  Different types of yeast fit better into different types of beer.  There are yeasts that are Ale specific (anything from Irish Ale yeast, Scottish Ale yeasts, etc.).  The reason behind the different types of yeast has to do with various factors.  I will highlight two.  First of all, a yeast may impart flavors that are more conducive to a brew style.  Brewers of wheat beers may want to impart a clove or banana type flavor to their brew.  The combination of grains and yeast will create a fertile ground for flavor profiles.  Secondly, the type of yeast chosen is practical in nature.  Some yeast strains are able to tolerate higher and lower levels of alcohol production.  The higher the alcohol production, the stronger the strain that is needed.  If you think about it, this is why something like kitchen yeast (for bread) is not suitable for fermentation.  It is precisely for the above mentioned reasons that this is true  (although, it is interesting to note, that some yeast strains do impart a bready quality to beers, provided that the flavor is desirable).

One more consideration is the fermentation temperature itself.  Various beers are actually fermented at different and controlled temperatures (fluctuations more than 5 degrees are discouraged).  The yeasts plays a distinctive role in the type of beer that is being brewed.  For instance, a lager is brewed at temperatures that remain between 55 (at the highest) and 32 degrees.  The yeast and temperatures create the clean taste that is often ascribed to Lagers.  Lager is actually a German word that means ”to store,” which is to say that it does not necessarily have to have a particular color to qualify as being a Lager.  In fact, Sam Adams makes a Black Lager, which might seem to be a contradiction in terms.  Suffice it to say that yeast and temperature both play a fundamental role in this process.  This is why ales are fermented at higher temps than Lagers.  Yeast will act differently at different temps.  Of course, the cooler the temps, the slower the fermentation.