Lactic acid and ethanol fermentation - Lab Report Example

? Number] Lactic acid and ethanol fermentation Introduction The word Fermentation is derived from Latin verb “fever” which means “to boil”. It is the process through which energy is derived from the oxidation of organic compounds such as carbohydrates, by using an electron accepter, usually an inner organic compound. In bio-chemistry, fermentation is an enzyme-catalyzed, a process of energy generation, in which organic compounds act both as donors as well as acceptors of electrons. The term is sometimes defined as the pathway in cells by which glucose / sugar molecules are broken down anaerobically. Historical perspective The historic uses of fermentation were mostly the creation of alcoholic beverages such as mead, wine and beer, which date back to 7, 000 BC in some parts of Middle East. However, the fermentation of food items such as milk and other vegetables was experimented almost thousand years later. In 1857, Louis Pasteur, a French Chemist connected yeast to fermentation and defined it as respiration without air. Later, in 1907, Eduard Buchner, the German chemist found out that fermentation is actually caused by yeast secretions which can even take place outside the living cells. In 1920s, scientist discovered that extracts of muscle catalyze the formation of lactate from glucose in the absence of air. They also revealed that fermentation reactions are not peculiar to the action of yeast but can also occur in many other cases of glucose utilization (Fruton, 2006, p-29). Ethanol fermentation It is a biological process that involves conversion of sugars i.e. glucose, fructose and sucrose to cellular energy, producing ethanol and CO2 as waste by-products which are metabolic in nature. Due to the fact that the yeast performs this function in total absence of oxygen, therefore this type of fermentation comes under the classification of anaerobic (Theiman and Palladino, 2009). The chemical equation representing the glucose fermentation resulting in the production of ethanol is as follows: C6H12O6 (glucose) > 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide) The most important of Ethanol fermentation is in the raising of bread dough. The sugar present in the dough is consumed by the yeast organisms consequently producing ethanol and carbon dioxide (CO2) as waste products. The presence of CO2, released as the waste product is responsible for its foam like expansion as it forms bubbles in the dough. Ethanol, on the other hand evaporates from the dough completely after the bread is fully baked (Kratz, 2005). Ethanol fermentation that is carried out by yeast is employed for the production of nearly all beverages containing alcohol except for those produced by maceration of carbon. In addition, the production of wines and brandies is carried out by the process involving fermentation of natural sugar of fruits, especially that of grapes. While beers, ales and whiskeys are produced by the fermentation of grain starches that is converted to sugar by application of enzymes called amylase that is present in germinated grain kernels. Vodka is produced by the fermentation of amylase-treated grains or potatoes, while the first step involved in the production of rum is the fermentation of cane sugar. In each and every process the fermentation must take place in a vessel that is specifically arranged to allow CO2 to escape, but at the same time preventing the external air from coming in, as formation of ethanol can only take place in absence of oxygen. The yet another use of yeast fermentation of various carbohydrate products is to produce ethanol that can be used for the fuels. Ethanol fuel is ethyl alcohol, the same type of alcohol which is found in alcoholic beverages. It is mostly used as biofuels additive for gasoline in motor fuels (alcohol and you). Method and materials used for making wine For making wine, grapes or berries are crushed, depending upon the type of wine that is to be made. Yeast is then added to this mush of crushed fruits that consumes the sugars released in their juices. A 5 gms packet of dry yeast or 35 ml to 175 ml of liquid yeast would be the right amount for making 5 gallons of wine. The ideal temperature for the fermentation process to take place effectively for wine production is 68 to 74 °F. A temperature that is out of this range will either stop the yeast from fermenting completely or it will die in the mid process without completing it. The juice and yeast mixture is stored in a container that allows the release of carbon dioxide but does not let oxygen to get to the mixture in the due process. The fermentation process takes some weeks after which the acquired wine is left to age to get better results. Lactic acid fermentation This type of fermentation occurs in the muscles of warm blooded animals, when they need energy faster than the blood can supply the oxygen (Roberts and Ingram, 2001). In other words, the cells can burn glucose anaerobically i.e. when oxygen is not available (typically during extreme exertion). In this process, pyruvic acid becomes lactic acid and makes our body sour and stiff during strenuous activities, thereby reducing the muscles’ energy (Roth, 2006). The equation representing this process is as under: Glucose > Pyruvic acid > Lactic acid + energy The muscles cannot get rid of this acid until it is gradually wiped away by blood stream, taking it to liver which is the only source of eliminating such acid. It also occurs in various kinds of bacteria such as lactobacilli as well as in various kinds of fungi. It is the type of bacteria that is responsible for converting lactose into lactic acid in yogurt to give it a sour taste. Lactic acid bacteria can be classified as homofermentative, where end product is mostly lactate, or heterofermentative, where some of the lactate is further metabolized and results in CO2, acetate or other metabolic products. Lactic acid, which is produced as a result of Lactic acid fermentation, is responsible for sour taste and for improved micro-biological stability and preservation of food. It also gives sour taste to the fermented vegetables such as traditional pickles and sauerkraut (Tortora et al, 2007). Methods and materials used for making yogurt Yogurt is made by first boiling milk and letting it cool to a temperature of 112°F (45°C). A full tablespoon of fresh yogurt that is already rich in lactobacillus bacteria is then added to a little portion of boiled milk. It is then stirred and the rest of the boiled milk is added to the mixture. The milk is to be stored for around four to six hours maintaining the above mentioned temperature. In the due process the lactobacillus bacteria convert the milk sugar i.e. lactose to lactic acid. After the milk is fermented to yogurt, it is refrigerated immediately to preserve it. Conclusion Both ethanol and Lactic acid fermentation are anaerobic respiratory systems which take place in absence of oxygen. In other words, fermentation process replaces aerobic respiration to provide energy the absence of oxygen. However, this kind of replacement is only temporary because cells need oxygen for sustained activity. In both fermentation processes, the goal is to regenerate NAD+, so as to drive glycolysis and produce ATP in the absence of oxygen. Although they both produce 2 ATPs (Adenosia Triphosphate that is a nucleotide containing a large amount of energy stored in phosphate bonds) each during the process as energy, but the energy efficiency differs; Lactic acid fermentation has 41% efficiency and ethanol has 29%. In ethanol fermentation, CO2 is split off and two carbon compound ethyls are produced as end result; whereas in lactic fermentation, the end product is three-carbon compound lactic acid. In both the processes, the end products are great source of autonomous energy, which is used in less / non- availability of oxygen. Both types of fermentation are used by primitive organisms that have been basically evolved in environment where there is no or very low level of oxygen available or this mechanism have been developed as a secondary survival technique like the parasitic or commensal worms in the stomach of mammals. Work Cited Fruton, Joseph S. Fermentation: Vital or Chemical Process? Leiden: Brill, 2006. Internet source. How is alcohol made? Retrieved from: http://www.alcoholandyou.org.uk/facts/howisitmade.html Kratz, Rene? F. Microbiology the Easy Way. Hauppauge, NY: Barron's, 2005. Print. Roberts, Michael and Ingram, Neil. Nelson Science – Biology. Nelson Thornes Ltd, 2001. Print. Roth, Stephen M. Why does lactic acid build up in muscles? And why does it cause soreness? Scientific American, 2006. Retrieved from: http://www.scientificamerican.com/article.cfm?id=why-does-lactic-acid-buil Thieman, William J, and Michael A. Palladino. Introduction to Biotechnology. San Francisco: Pearson/Benjamin Cummings, 2009. Print. Tortora, Gerard J, Berdell R. Funke, and Christine L. Case. Microbiology: An Introduction. Pearson/Dorling Kindersley (India) Pvt. Ltd, 2007. Print. Read More