Understanding the Difference - Ale VS Lager
Understanding Lagers VS Ales
Hugh Sissons Diary of a Brewer
I am often asked (especially when I am doing our public brewery tours) about the difference between ales and lagers and beers. I hear discussions of top fermenting yeast (ales theoretically) versus bottom fermenting yeast (lagers, so they say), and even if where the yeast does its work were consistently true (it is not in all cases), it does absolutely nothing to explain the flavor differences between the two major types of beer. Consequently, in my opinion, top versus bottom is completely useless! More edifying is to discuss flavor differences in ales versus lagers.
Beer is the overall generic term for fermented malt beverages whether it is an ale or a lager, it is still called beer! There are ONLY two kinds of beer ales and lagers. Within those two broad categories there are many styles. Major ales styles are pale ale, IPA, porter, stout, and barleywine, just to name a few. Among the major lager styles are pilsner, Mrzen, bock, and dunkles (dark lager).
What really differentiates an ale from a lager is the temperature of fermentation. Ales ferment typically between 64 and 70 degrees F, and lagers ferment typically between 52 and 58 F. Fermentation is the process whereby yeast consumes the sugars from the malt, and in turn produces alcohol and carbon dioxide. All yeast strains, in addition to producing alcohol and CO2, also produce small amounts of other compounds which add subtle flavor complexity to the beer.
With warmer fermentation temperatures (ales), yeast will produce elevated ester compounds. These come across on the palette as a rounded fruitiness, and give ales their characteristic complexity. Typically, ale yeasts will not ferment at colder (lager) temperatures.
Colder fermentations obviously require a yeast that is genetically capable of fermenting at colder temperatures (as opposed to ale yeasts). The colder temperatures prevent these lager yeasts from producing the amount of esters which are so characteristic of ales. However, many popular lager yeasts do produce elevated sulfur compounds during fermentation. These sulfur compounds take extended cold storage (known as lagering) to be pleasantly integrated into the beer, but once accomplished, these compounds show on the palette as crispness and cleanness.
This is all a bit of an oversimplification, but it is helpful to understanding the basic differences between the two types of beer. Ales can be referred to as being fruity, rounded, and complex, and lagers can be referred to as being crisp, clean, and angular. A close sampling of normal strength (ie around 5% ABV) examples of each type will illustrate these concepts from a sensory perspective. So have a couple of beers you pick the type and see if you think I am right!
