A student found a recipe for making elderberry wine by fermentation.
- 1kg elderberries
- 0.5kg sugar
- 10g yeast granules
- 3dm3 water
The student decided to make some elderberry wine using the apparatus below.
The student carried out the following method.
Step 1 The elderberries were crushed.
Step 2 The crushed elderberries and sugar were added to the water and the mixture was boiled for ten minutes. The crushed elderberries were then separated from the mixture.
Step 3 Yeast was added to the liquid when it had cooled to room temperature.
Suggest the purpose of the airlock in the apparatus.