Where does the alcohol come from in beer?
While the process of making beer is extremely complex and varies greatly from brewery to brewery and beer to beer, there are a few constants. Almost all beers are made with a malt -- usually barley -- but sometimes wheat, oats, other grains or a combination of them. In addition, hops are used to counteract the sweetness of the malts. Then there is the key ingredient, water. In mass-produced American beers, corn and rice are often added as cheap sources of fermentable sugars. In the brewhouse, the ingredients are processed to make a liquid extract called wort, basically sugar water ready for fermentation.
This wort is then cooled, yeast is added and the two settle in a fermentation tank. A few days' time allows the yeast to turn the sugars into ethanol and carbon dioxide during fermentation. Thus yeast is responsible for turning a cold, sugary water into a carbonated alcoholic beverage. From here, further aging and processing refines the product.
The process of making beer is obviously more complex than this, and a more detailed explanation will be appearing in the future.
What are the differences between all these different types of beer: ales, lagers, pilsners, bocks, etc...?
There are two primary divisions in beer styles -- ales and lagers.
Almost all other subdivisions fall into these two categories. Most porters, stouts, hefeweizens, barley wines, wheat beers and Belgian dubbels fall into the ale class, along with the obvious pale ales -- India pale ales, blonde ales, red ales, etc. On the other hand, most pilsners and bocks are lagers.
The main difference between the two divisions is the type of yeast that's used for fermentation. Ales use a top-fermenting yeast, meaning it settles on top of the wort. This is the term for beer before it's the official beer we know in the fermentation tanks. For lagers, just the opposite is true. This yeast is bottom-fermenting, and fermentation temperatures are typically around 45 to 55ÃpF. For the top fermenting yeast, warmer temperatures near 60 to 70ÃpF are more suitable.
Of course the variety of ingredients is immense, but the type of yeast is the major factor in separating the two divisions. From here, an assortment of variables, most importantly malt selection, further classify the two specific styles.
The style that is most common is specifically known as an American Macro Adjunct Lager, an American style in origin and typically made by large brewers (also known as macrobrewers). Adjuncts are used to lighten the flavor and cut costs, using bottom-fermenting yeast. Thus, Pabst Blue Ribbon, Michelob Ultra and others are technically just as much lagers as is Yuengling Lager.
Many libraries worth of books could be (and have been) written on styles of beer. For more detailed information visit http://www.beertown.org/education/styles.html and download the PDF on styles.
Chris Straub is a senior majoring in chemical engineering and a Collegian columnist. He is the great-great grandson of the founder of Straub Beer. His e-mail address is cts150@psu.edu.
Suds Snippet
According to the Beer Institute, the oldest written recipe in the world is for beer. Found on a 4,000-year-old Mesopotamian clay tablet, this was not just any old recipe, but according to the tablet, handed down from the god Enki.
