The Chemistry of Alcohol

Alcohol is a class of organic compounds that is characterized by the presence of one or more hydroxyl groups (-OH) attached to a carbon atom. Alcohol was unknowingly produced centuries ago when fermentation occurred to crushed grapes (Pines, 1931). In today’s society alcohol is produced for the use of household products such as varnishes, cleaning products, but is more commercially important in the liquor business. A chemical process called fermentation accomplishes the production of ethanol, the alcohol or liquor. From there, the ethanol goes through distinct processes to become the dark and clear liquors on the store shelves.

The process of alcoholic fermentation begins with the use of enzymes. The enzymes begin to break down the long chains in starch molecules, a polysaccharide that consists of a large quantity of glucose molecules (C6H12O6) joined by glycosidic bonds as seen in figure 1, into single glucose molecules, a monosaccharide with six carbons and five hydroxyl groups. After the starch has become sugar, the enzymes are used once again, this time to convert the sugars into ethyl alcohol and carbon dioxide, CO2, as seen in figure 2 (World of Scientific Discovery, 2007). The carbon dioxide produced is released into the atmosphere, leaving water and ethanol, the alcohol, behind. Ethanol is a colorless flammable liquid with a molecular formula of C2H6O, giving it a molar mass of 46.07 grams per mole. Ethanol is also characterized by a melting point of -114°C or 159 K.

All types of alcohol go through a fermentation process, when looking sthe production beer, the fermentation process contains a series of distinct stages. Beer includes four main ingredients; some sort of grain (wheat, corn, barley), hops, water, and yeast. The beer process begins with the malting process, the stage where the grain is soaked in water for days to allow adequate germination time. This process is important because allowing the grain to germinate produces enzymes that are need to break down starch in succeeding steps. At times, the conversion of starch to sugar can begin during malting due to enzymes present within the grain, but the majority of the conversions begin in the next step (Michaels, 2010). Following the malting process, the grains go through a process called mashing, defined as the stage where the grain is hydrated causing the enzymes to activate and begin converting the starches into sugars. In the mashing stage enzymes are activated and begin to convert starch into sugars that will eventually go through the fermentation process.