Chemical reactions in beer

Abstract

Beer is a complex alcoholic beverage made from barley (malt), hops, water and yeast. Chemically, beer can be considered as a water-ethanol solution with an acid pH (pH around 4.2) which contains hundreds of dissolved
molecules. Thermodynamically, a bottle of beer is a closed system and will thus strive to reach a status of minimal energy and maximal entropy. Consequently, molecules can undergo different reactions and change their chemical composition during storage. Moreover degradation of molecules to concentrations below the flavour threshold may cause loss of initial fresh beer flavours. In this article, we discussed the fundamental reactions
in beer and their mechanisms from brewing to storage.