Plants are a source of carbohydrates and oils which can be used for food, fuel and many everyday products. Carbohydrates are compounds which contain the elements carbon, hydrogen and oxygen.
Fermentation is a reaction which breaks down glucose obtained from fruit and vegetable sources to form the alcohol ethanol and carbon dioxide.
An enzyme in yeast acts as a catalyst for the reaction.
\[Glucose \to ethanol + carbon\,dioxide\]
\[{C_6}{H_{12}}{O_6} \to 2{C_2}{H_5}OH + 2C{O_2}\]
There is a limit to the alcohol content of fermented drinks of about 12 per cent. This is because alcohol is toxic and it kills the living organism yeast, before too long.
Depending on the concentration of alcohol required, fermentation only or fermentation followed by distillation may be used.
Alcoholic drinks known as spirits have higher concentrations of alcohol. These include whisky and vodka and are produced by a process called distillation which separates out the alcohol that has been produced.
| Raw Material | Product | % | Method |
|---|---|---|---|
| Barley | Beer | 4 - 5 | Fermentation |
| Barley | Whisky | 40 | Fermentation then distillation |
| Potato | Vodka | 40 | Fermentation then distillation |
| Sugar Cane | Rum | 40 | Fermentation then distillation |
| Grape | Wine | 12 | Fermentation |
| Grape | Brandy | 40 | Fermentation then distillation |
| Grape | Sherry | 20 | Fermentation then add extra alcohol |
The alcoholic content of drinks is measured in units. Some different unit contents are shown in the table below.
| Alcoholic drink | Units |
|---|---|
| Pint of beer | 2 |
| Measure of whisky | 1 |
| Bottle of alcopop | 2 |
| Glass of wine | 1 |
Our bodies perform many chemical reactions in everyday life which keep us healthy. Medicines contain drugs (substances that affect the body) that can help the body when it is not working correctly. Antibiotics are drugs that fight micro-organisms present in our bodies that cause illness and prevent our bodies from working properly. Many medicines that we use including aspirin have been produced from chemicals found in nature. Plants produce useful chemicals that chemists can analyse and improve upon.