Beer
Beer is an alcoholic drink typically formed from a malted cereal crop such as barley or wheat or other source of fermentable sugar, bittering ingredients such as hops, yeast such as Saccharomyces cerevisiae and water. Many different styles of beer (and similar fermented drinks) exist and beer production has been very important for civilization as a source of drinkable water prior to modern sanitation techniques.[1] The alcohol, antibacterial properties of hops and low pH environment cause beer to be a harsh environment in which most food-spoiling microbes cannot grow. The alcohol in beer is formed from the fermentation of simple (fermentable) sugars by yeast or other microbes.
Ingredients
Grains, Malts & Other Sources of Fermentable Sugars
Grains of various different types are chosen as ingredients in beer for their ability to provide starch, endogenous enzymes, nitrogen compounds and other trace nutrients that support the growth of yeast to produce alcohol. The most common ingredient in modern beer is malted barley. Malted barley is barley that has been steeped in water, allowed to germinate and then is gently dried to a low moisture content to aid with storage, preserve enzyme activity and retain starches. Malted barley contains starch which is broken down in the mashing process into sugars such as glucose, maltose, maltotriose among others. Malted barley contains several key enzymes which are able to carry out this process such as amylases. Free amino nitrogen compounds are provided by the breakdown of larger storage proteins in the malt by proteases.
Several different Cereal crops are suitable for malting, not just barley, these include:
- Wheat
- Oats
- Sorghum
- Rice
- Rye
Bittering Ingredients
Hops are used in modern beers to provide bitterness and contribute to the microbial stability of beer through alpha acids, iso-alpha acids and beta acids.
Yeast
Water
Production Methods
Summarised in Brewing