The main ingredients used for beer making are water, malted barley, hops, and yeast. Other additives such as flavoring and sugar are commonly included. In addition, starches are added to convert in the mashing process to ferment-able sugars which helps to increase the alcohol content of beer while adding body and flavor.
Since beer is mainly composed of water, the source of water and its mineral content have a very important effect on the character of the beer. A lot of beer styles were influenced by the uniqueness of water in the region. Although the effect of minerals in water for brewing is complex, basically hard water is more suited to dark styles, while soft water is more suited to light styles.
Among malts, barley is the most widely used due to its high amylase content, and a digestive enzyme that facilitates the breakdown of starch into sugars. Depending on what can be cultivated locally, other malts and non-malted grains can be used, such as wheat, rice, oats, and rye.
Malt is obtained by soaking grain in water, allowing it to germinate, then drying the germinated grain in a kiln. By malting the grain, enzymes will eventually convert the starches in the grain into ferment able sugars.
Since the seventeenth century, hops have been commonly used as a bittering agent in beer. Hops help to contribute a bitterness that will balance the sweetness of the malts. They also contribute aromas which range from citrus to herbal.
Hops also provide an antibiotic effect that favors the activity of brewer’s yeast over the less desirable microorganisms. The bitterness in beer is normally measured on the International Bitterness Units scale.
Yeast is a microorganism that’s responsible for fermentation. Specific strains of yeast are chosen depending on the type of beer produced, as the two main strains are ale yeast and lager yeast, with other variations available as well.
Yeast helps to metabolize the sugars that are extracted from the grains, and produces alcohol and carbon dioxide as a result. Before the function of yeast was understood, all fermentation’s were done using wild or airborne yeasts.
A lot of brewers prefer to add one or more clarifying agents to beer that aren’t required to be published as ingredients. Examples include Isinglass finings, which are obtained from swim bladders of fish and also Irish Moss, which is a type of red algae.
Since these ingredients can be obtained from animals, those who are concerned with either the use or consumption of animal products should obtain detailed information from the brewer.
You should also read this page about beer grains