The enzymatic yeast fermentation takes place according to the following equation:
C6H12O6 → 2 C2H5OH + 2 CO2
The actual course is, however, far more complicated and occurs in several separate steps with ATP involvement. In addition to ethanol, large amounts of lactic acid, other carboxylic acids and higher alcohols, are formed. Pure sugar solution is less well fermented, because of the high sugar concentration and the lack of mineral substances. The fermentation rate can be increased by adding a spoonful of flour or nutrient salt.

The experiment is very suitable for work-sharing. Various fruit juices can be used. A parallel test with sugar solution should always be carried out, to demonstrate that sugar is the substance which ferments.

Learning objectives

• Alcohol is produced from sugar containing liquids by fermentation with yeast.
• The sugar is split by the yeast fungus to alcohol and carbon dioxide.

Benefits

• Easy teaching and efficient learning by using interactive experimentation PHYWE-Software
• Experiment is part of a complete solution set with experiments for the topic Organic Chemistry matched with international curriculum: all topics are covered