Microbes are all around us – in the air, the soil, water and our bodies. This means they can soon get into food and, if the conditions are right, multiply rapidly. Unfortunately, when certain microbes grow on food, it soon begins to smell nasty, look slimy, change colour, taste awful or even acquire a furry coating. The food ‘goes off’ – it is spoiled. Even though it may not harm us, it is inedible and must be thrown away. There is also a chance that pathogenic microbes are present along with the spoilers.

Around a quarter of the world’s food supply is lost to spoilage by microbes and insects. So what can we do to outwit the microbes and ensure that we consume the food before they do? Over the years man has developed many ways of preserving foods and today’s food technologists have refined the techniques and come up with new ones.

We should remember that spoilage is not necessarily a bad thing. It shows us that a food has not been made or kept in the best conditions, alerting us to the possible presence of pathogenic microbes.

Also decomposition returns the chemicals in food back to the environment, to be used again in the life cycles of Earth.

There are three main types of microbes that cause spoilage:

• bacteria
• yeasts
• moulds