Question

3· The upper limit for alcohol content in beers and wines is about 10%. However, whiskey can have an alcohol content in the 40-50% range. Why is this? what did we do in this lab that is relevant to this process?
Please help me answer this question.

Answer 1

Answer:

Alcohol in beer and wine is produced by yeast cells (example Saccharomyces cerevisiae) by process of fermentation.
Yeast + Glucose (C₆H₁₂O₆) ---> Ethanol (2CH₃CH₂OH) + 2CO₂ + Heat

During fermentation process, the alcohol is accumulated and when the concentration of alcohol reaches around 14-18% it becomes toxic to the yeast cells and can kill the cells. The cells ar grow well in low alcohol concentrations. After reaching a concentration of around 8-10% alcohol, there is a significant drop in viability of cells. Therefore the upper limit to which beers and wines can contain alcohol is 8-10%.

To increase the concentration of alcohol in liquor further, a process called as distillation is required. Second option is to use yeast cells that are tolerant to high alcohol concentrations.

In the process of distillation, water content in alcohol is reduced leading to a higher concentration of alcohol. Since whiskey is produced by distilling alcohol, therefore, the concentration range of 40-50% can be reached.