Fermentation

Fermentation reactions occur when microorganisms take in food and convert it into substances which are useful to them. The microorganisms also release waste substances such as carbon dioxide.

The most common example of fermentation is when yeast (Saccharomyces cerevisiae) – a single-celled fungus - converts sugar (glucose) into alcohol. Here are the word and balanced formulae equations for this process:

glucose → ethanol + carbon dioxide

The following conditions are maintained to maximise growth rates:

1. The fermenter is kept aseptic so only the desired microorganism grows.

2. Nutrients are provided to ensure that the microorganisms always have enough food to grow.

3. The optimum temperature and pH is maintained to ensure maximum growth.

4. There is an oxygen supply because most fermentation reactions are aerobic.

5. Agitation (stirring) takes place to ensure that the microorganisms, nutrients and temperature are evenly distributed.

Microorganisms and food production

We use microorganisms to make a large number of our food and drink products – these include bread, yoghurt, cheese and alcohol.

Microorganisms are useful because:

• they grow rapidly

• they have DNA which is easy to manipulate

• they can be grown in fermenters in almost any location (the local weather doesn’t normally affect their growth)

• they can be grown using the waste products from other industrial processes

Examples : Mycoprotein ( Fusarium) Which is used for vegetarians and Yoghurt Which is fermented from milk. Lactose( main sugar in milk) is converted to Lactic acid.