OBJECTIVE: To see how different yeasts influence and influence the rate of fermentation, how much alcohol is produced and how this affects the overall quality of the wine produced. BACKGROUND INFORMATION: Alcohol is primarily thought of as ethanol, which is the alcohol found in alcoholic beverages such as wine and beer. But there are many different varieties of alcohol such as methanol, propanol and butanol. In chemical terms, "alcohol" is a compound of a hydroxyl group covalently bonded to a carbon chain which can be seen in figure 1. In the course of this experiment ethanol is the alcohol produced during the process of fermenting the sugar present in must or grape juice. Figure 1: Chemical structure of ethanol (Wikimedia, July 19, 2009) Yeast is a single-celled living organism necessary in the fermentation process of grape must. Invertase, an enzyme found in yeast, acts as a catalyst to accelerate the chemical reaction in which sucrose is converted into fructose and glucose. (Donal O'Leary, 2000)Figure 2: The word and balanced equation of the conversion of sucrose to simple sugars (Donal O'Leary, 2000)Another enzyme found in yeast is known as zymase. It is this enzyme present in yeast that converts the glucose and fructose produced into ethanol and carbon dioxide. (Donal O'Leary, 2000)Figure 3: The word and chemical equation for the conversion of simple sugar to ethanol (Donal O'Leary, 2000)In wine production there are 2 fermentation processes known as• Primary fermentation• Secondary FermentationIn in the process of primary fermentation sucrose is converted into glucose and fructose and glucose...... middle of paper ...... serves for their growth and development. 5 ml of each bucket was added to the specified beaker and left for 10 minutes. 90 ml was then added to the specified beaker and left for another 10 minutes. This process activated the yeast. Once activated the yeasts were added back into their specific bucket at 1 point of the grape must. The grape must was not agitated and was slowly and carefully placed in a cooler environment where it could begin the fermentation process. After 8 days of primary fermentation the grape must was filtered using a sieve and cloth to remove any dead yeasts and skins. The grape juice was then poured into the specified bottle and an air bladder was placed on top to prevent oxygen from entering but allow carbon dioxide to escape so that pressure did not build up in the bottles. This started the secondary fermentation process.