Essay On Fermentation

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Fermentation is an anaerobic metabolic pathway used to oxidize NADH into NAD+. Fermentation is used to produce alcoholic beverages such as wine, and acidic dairy products, such as yogurt. In the absence of air, microorganisms called yeast convert sugars to alcohol. According to the book, “During fermentation, electrons are transferred (along with protons) from reduced coenzymes (NADH, NADPH) to pyruvic acid or its derivatives. An essential function of the second stage of fermentation is to ensure a steady supply of NAD+ and NADP+ so that glycolysis can continue. In fermentation, ATP is generated only during glycolysis.”(Tortora). There are a few different types of fermentation; the ones used for this assignment were Lactic acid fermentation and Ethanol fermentation. During Lactic acid fermentation pyruvate, produced by glycolysis, takes a proton from NADH and fermentation regenerates NAD+ by making lactate. In order to make yogurt, bacteria called Lactobacillus bulgaricus and Streptococcus thermophilus produce lactic acid in the milk culture, which causes the pH to decrease and makes the environment acidic. Ethanol fermentation uses yeast to break pyruvate into acetaldehyde, which makes carbon dioxide. Through the oxidation of NADH glucose becomes ethanol and carbon dioxide. Just like Lactic acid fermentation, Alcohol fermentation utilizes a molecule of glucose that goes though glycolysis and produces two molecules of pyruvic acid and two molecules of ATP. The two molecules of pyruvic acid are converted into two molecules of acetaldehyde and two molecules of CO2. The molecules of acetaldehyde are reduced by molecules of NADH, which then end up forming the ethanol. In order to start Lactic acid fermentation we will attempt to make... ... middle of paper ... ...he results of the yogurt production after 3 days are as follows: the yogurt has a semi-solid texture, acidic smell, and a sour taste indicating that Lactic acid production took place. The wine production results after the same amount of time was as follows: the wine smells slightly of alcohol, the amount of liquid decreased, and some bubbling is still present; the balloon is currently inflated and producing carbon dioxide. Based on these results the ethanol fermentation was also successful. During both of these experiments fermentation took place, in the case of the yogurt the Lactic acid gave the yogurt a tart taste and smell, and in the Ethanol fermentation the wine smelled of alcohol and produced carbon dioxide indicated by the air in the balloon. In conclusion, NADH was oxidized and Lactic acid and ethanol were produced in both experiments through fermentation.

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