Beer, in its purest form, is comprised of water, malted barley, hops and yeast. Its brewing is an ancient art dating back to Mesopotamia, ca. 2000 BC, the same region where barley is believed to have first been cultivated. As the cultivation of barley spread, so did beer. And so, in time, the peoples of Europe became especially skilled at the art of brewing. While most of the Mediterranean cultures preferred wine (their climates being favorable to the cultivation of grapes), the more northern lands, especially Germany and England, came to embrace beer.

Beer has since spread around the world, enjoyed by nearly every culture that it has touched. Although there are almost as many different styles as there are people that drink beer, this "nectar of the gods" still relies upon four basic ingredients: water, malt, hops and yeast.

There is a tremendous amount of variation on the brewing process involving different kinds of malt, hops, and yeast. Even the type of water used has a distinct effect upon the flavor of the finished product.

Water
Not surprisingly, the ingredient that makes up most of the volume in beer also has a great affect upon its taste. There are two variables that are important considerations when brewing beer, the alkalinity (or pH level) and the amount of minerals in the brewing water. Put simply, low alkaline water is most conducive to the enzymes that break down the starches present in the brewing grains and/or adjuncts. Calcium ions, the most significant mineral in the brewing process, react with the phosphates naturally present in the grains and thereby lower the pH level of the mash. Additionally, calcium tends to promote the enzymatic degradation of starch, aids in the hop-flavoring process, and inhibits certain off-flavors from developing in the beer.

The most famous beer-making regions rely upon the qualities of the local water to make their brews unique. And indeed, you may notice that all brands of beer from a particular brewery have a similar under-riding flavor that, more often than not, is caused by the source of water.

Malt
Probably the single most vital ingredient in beer is the malted barley that the yeast ultimately relies and feeds upon. Not coincidentally, the earliest civilizations to harvest barley are also regarded as those first to process the grain into beer.

Malt is made by a manner in which the edible seeds of the barley plant (known as barleycorns), produce the sugars and starches necessary for brewing, as well as the enzymes that will break down those starches into more palatable sugars. Essentially, the barley is allowed to germinate through immersion in water and then allowed to dry at a controlled and steadily increasing rate. During germination, the barleycorn naturally generates sugars and starches essential for growth and development of the new barley plant. Maltsters control this process to produce a variety of malts. The rootlets produced during germination are then removed, and the malted barley is then ready for use in brewing.

Once the barley is malted, the brewing process may begin. The first step in this process involves converting the starches into sugars through a method called mashing. There are several ways to mash the malt, but essentially, the grains are added to water and heated to a specific temperature and kept there for a specified amount of time (is that vague enough?) This heat-rest procedure (it is sometimes performed in stages, known as step mashing) activates the alpha- and beta-amylase enzymes that proceed to degrade the malt starches into fermentable sugars.

Roasting malted barley and certain methods of tweaking the malting process produces "specialty" grains like black patent, chocolate and crystal malts. These are employed as flavoring and coloring agents for many varieties of beer, but often contain no enzymes.

Hops
Hops are the aromatic flowers of the hop vine (Humulus lupulus). The cultivation of hops dates back to at least the ninth century, and were used for medicinal purposes, as well as for flavoring beer--though this practice was generally restricted to Germany. Hops were also found to be a natural antiseptic and preservative. Other plants and herbs were recognized for their preservative attributes (spruce, ginger, sage, etc.), but hops became the favored choice due primarily to its ease of cultivation and its flavoring qualities.

The major hop-producing regions of the world generally lie within areas that have cool, wet climates, namely Germany, southern England, southern Australia, Tasmania, and the Pacific Northwest region of the United States.

Yeast and Beer Styles
There are two basic types of beer: ale and lager. Ales are produced using a strain of yeast known as Saccharomyces cerevisiae. These yeasts thrive at warm temperatures (60° to 75°F), and are termed "top-fermenting" as they do their business at the top of the wort. Ale was once the most widespread style of beer as it could be brewed almost anywhere and at virtually any time of the year. Types of beer made with ale yeast include porters, stouts, and of course, ales.

Lagers are produced in colder temperatures (50° to 55°F for initial fermentation, and 32° to 45°F thereafter). Yeasts used in this process (Saccharomyces uvarum) are called "bottom-fermenting" as they--you guessed it--thrive at the bottom of the wort. Beers brewed in this way can trace their roots back to pre-medieval Bavaria, where beers were brewed and stored in dark, cold caves. Wild yeasts that inhabited such environments fed on the wort and the results were pleasing enough that the practice continued.

Lager-fermented beer styles include pilsners, bocks and doppelbocks.

Apart from the aforementioned yeasts and their sub-types, or strains, there are many other kinds employed by brewers, depending on local tastes and regional traditions. Some Belgian brews, like the renowned lambics and krieks, are fermented using a variety of wild yeasts as well as certain, brewery-specific bacteria.

A Word on Adjuncts and Sundry Ingredients
It is possible to extract fermentable sugars from grains other than barley. And although they significantly alter the outcome of the beer, brewers have not hesitated from using them, often with pleasing results. These other grains, or adjuncts, include rice, maize, rye, wheat and even oats. Rice for example, although it does not inhibit the malt flavor, lends a dry crispness to the beer. Wheat is combined with barley to produce the famed German weissbiers.

Most of the commercial American breweries use rice, corn or other adjuncts as an additional source of sugars. They did so in the beginning mainly to cut costs, but the results have been so popular that it has become a style all its own.

The Germans, on the other hand, have a purity law known as the Rhineheitsgebot, which strictly dictates the quality and type of ingredients allowed to be put in beer. Most American microbreweries and brewpubs follow similar standards in order to make beers that are far superior to their mass-produced cousins.

Additionally, many things can be added to enhance or otherwise alter the taste of the beer. Many of the popular Belgian brews use raspberries or cherries. Chili peppers, honey, raspberries, pumpkin, spruce needles--all have been added to beer (with varying results!)

American Tastes
Ales were the most popular types of beer in America until the great influx of Germans began to arrive on our shores in the 1830s and 1840s, bringing with them their traditions and culture--not the least of which was their tremendous knowledge of brewcraft. It was about this time too that scientific interest in brewing had reached the point whereby lager yeasts had been identified and a viable means for transporting them across the Atlantic had been found.

Lager beer rapidly became the popular favorite and, although ales never completely fell out of favor, it was not until the last fifteen years or so that the traditional American Pilsner had any real competition in the U.S. marketplace.