Water, Barley, Hops, Yeast

The short descriptions below provide only the most basic introductions to the main ingredients in beer. Each ingredient has multiple books written on the topic and college level courses delve into each topic. 

Water is the key ingredient in beer, although consumers overlook it. Brewing water is both complicated and simple at the same time. 

Water is a medium to hold molecules. Very simple right? However, the exact amount and specifics of each molecule is what makes water appropriate for brewing, as well as providing color, aroma, bitterness, fruity flavors, and so on in a glass of beer. 

It seems that once you try to understand water chemistry, you go down a deep hole of learning that just gets more complicated at every turn. The complexity comes from the fact that molecules interact with each other depending on variety of enviroments and circumstances. As the circumstances change, the molecular reactions change which makes water chemistry hard to master. 

 

Malted barley is mostly used to provide a host of things to beer. There is so much to say about malts, that is hard to know where to start. From the consumer's perspective, malts provide a spectrum of color to make beer not look like clear water, and some of the flavors in beer such as a coffee taste.

Very importantly, malts provide fermentable sugars for yeast to convert into alcohol. Who would want to drink a black imperial stout beer that has color and taste of coffee, but no alcohol? Wouldn't that be called "cold coffee?" 

Hops provide a number of attributes to beer. The chief contributors to beer are bitterness (otherwise beer would be undrinkably sweet) and preservatives (otherwise beer would not last more than a few days). Hops also provide flavors to beers which are described as Citrusy, Earthy, Floral, among others. These hop flavors come from oils in the hop plants. The hop variety (such as Cascade) and the terroir (such as England, verus Germany), both define the aroma and flavor that the hop provides.

Yeast's primary function is to consume sugars and produce alcohol.  Yeast also produces by products of desirable flavors, and CO2. The flavors produced by yeast are managed by selecting a certain strain of yeast and controlling the fermentation temperature. In reality, yeast is the ingredient that makes beer and manipulating the fermentation process is an art in itself. 

These ingredients are the basics of any beer. Other ingredients can be added to specific beers, such as fruit, coffee or chocolate to make seasonal beers.