Essay On Yeast Fermentation

1 Introduction

Fermentation serves as the basis of alcohol production; it is an exothermic reaction as heat is given off. Alcohol fermentation is done by bacteria and yeast. (Freeman, W,H. ) Yeast (Saccharomyces Cerevisae) is a unicellular fungi which reproduces asexually. (Lesaffre, n.d.) These microorganisms are responsible for decomposing large organic molecules such as glucose into pyruvate. (Mann, 2013) This occurs under anaerobic conditions through a process called glycolysis, which is the dissolution of enzymes sugar caused by enzymes from hte yeast which converts sugars into alcohol. As the yeast are responsible for fermentation, the temperature during fermentation must be controlled to ensure that these fungi catalysts are not denatured due to the temperatures being too high or too low. An excess of alcohol in a solution will cause the yeast enzymes to die, hereby, terminating the fermentation process. These dead yeast cells which remain

(Britannica Encyclopedia, 2010) The pyruvic acid is converted to ethanol and carbon dioxide, which are metabolic waste products. The carbon dioxide yielded from the reaction produces a foam layer on top of the liquid, known as krausen, and it serves as a protective layer against bacteria. (Exchange, 2015) While the carbon dioxide is released from the mixture, the ethanol remains in the mixture.

During the fermentation of wine the following reaction takes place:

C6H12O6 → 2C2H5OH + 2CO2

Once this primary fermentation stage of the wine is complete, further fermentation takes place in what is known as the secondary fermentation stage, during which time any particulate matter – such as dead yeast cells – settles at the bottom. The primary stage occurs within the first 4-7 days of fermentation, and the secondary stage lasts 2-3 weeks after that.

3.4. Analysis of