The Chemistry of Alcohol
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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.
The mashing stage is also subjected to a series of optimal temperatures at set intervals. By exposing the mash to different levels of temperature, specific enzyme groups are favored allowing the brewer to adjust the mash temperature to favor a certain enzyme’s function and thereby customize the taste and purpose of the wort. For example, majority of the starches in a mash are 90% soluble when the mash reaches 130° F, but they reach maximum solubility at 149° F (Palmer, 1999). After the mashing process, the grain husks are removed, leaving behind a sugar and water mixture called a wort. Due to the sweet flavoring in the wort, hops are added because of their bitter flavor and aroma. Following the addition of hops, the beer is prepared for fermentation by the addition of yeast. Depending on what the beer is brewed for, different yeasts are added. After an initial fermentation process usually lasting three to seven days, the remaining yeast is drained. If the brew is to be a lager, it is placed in cold storage for weeks, otherwise if it is used in a keg it is used within six weeks.
Once the beer or any alcohol is consumed, chemical reactions take place within the body. The alcohol reaches your liver two ways; one way involves it being absorbed through your stomach walls and eventually into your blood stream this, happening about 20% of the time. The second way is through absorption by the small intestine, which accounts for 80% (Bunce, 2010). An important term when dealing with the ingestion of alcohol is blood alcohol level or content (BAC), which is when alcohol is ingested faster than the liver can oxidize it and alcohol builds up in the blood stream. BAC is measured in milligrams per 100 millimeter of blood; For example the legal limit is 0.08, which means 0.08 mg of alcohol in 100 ml of blood. Alcohol content also affects behavior. At a blood alcohol content, of 0.003, which is the equivalent of 1 ounce of liquor per hour, there is a feeling of euphoria. At 0.30, which is the equivalent of 8 beers an hour, behavior is observed as breathing reflex threatened and a deep anesthesia state (Bunce, 2010).
A common side effect of drinking is the onset of a headache, a common sign that the body is trying to rid itself of a toxic substance; in fact, 75% of those who get intoxicated will experience a hangover (Singh, 2003). One of the causes of hangovers is a congener, which are organic compounds with toxic effects that are responsible for the odor, taste, and color of alcohol. Common examples include acetone, fusel oil and tannins. (Rohsenow et al, 2010). Congeners, produced during alcohol maturation, are more commonly associated with darker liquors such as wine, brandy, and whiskey as research shows that those 33% of those ingesting darker liquors experienced a hangover compared to the 3% of cases that arouse in those drinking clear liquors such as vodka, gin and white rum (Singh, 2003). The reason for more congeners in darker liquors is due to the amount of filtration; Since darks such as brandy and whiskey are looking for the oak flavoring they receive little filtration compared to Vodka which experiences the most filtration. Acetaldehyde, an organic compound, is also tied to hangovers. Because ethanol is toxic to the body, the liver oxidizes ethanol to acetaldehyde by enzymes called alcohol dehydrogenase, but the problem is that acetaldehyde is actually more toxic (Clegg, 2014). Due to acetaldehyde’s toxicity, the body then converts the acetaldehyde to acetic acid by acetaldehyde dehydrogenase as seen in figure 3(Clegg, 2014).
Attributable to the body’s compensation for the intake of alcohol by using enzymes to convert toxic ethanol, the body experiences symptoms associated with hangovers because the enzymes are unavailable to do their original jobs, usually contributing to a drop in glucose levels which is associated with headaches, dizziness, and nausea (Clegg, 2014). Another cause of hangovers is dehydration. Alcohol also contributes to the dehydration effect due to its diuretic properties. During dehydration, the body secretes diuretic hormones, causing the kidneys to preserve water and causing the urine to be a yellow color indicating that the urine is highly concentrated. When alcohol is ingested, it interferes with this safety valve, causing the body to rid itself of more liquid when it should be conserving leading to the headache (Bunce, 2010). Alcohol can also contribute to the nauseating factor because it stimulates the secretion of extra acid in the stomach, irritating the mucous lining of the stomach (Bunce, 2010).
High levels of alcohol in the blood stream can be prevented. Because one of the ways alcohol enters the liver and blood stream is through the small intestine, having protein and carbohydrates in the stomach slow the intake of alcohol within the blood stream allowing the liver to catch up with oxidizing the alcohol (Bunce, 2010). Hangover effects can be lessened the night before by replenishing the body with liquids, such as water but not carbonated beverages because the carbon dioxide in them causes the blood to intake the alcohol at a more rapid pace (Bunce, 2010). The best way to prevent side effects of alcohol is to allow time in-between ingestion so that the liver has time to oxidize the ethanol.
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http://www.howtobrew.com/section3/chapter14-1.html Web. 4 May 2014