Background: foodborne microbes

Links to activities: spot the mistake discussion sheet, food sort, and how clean is your kitchen.

In week one we discussed that there are both useful and harmful microbes present in food.

• Useful microbes can be used to make different kinds of food and drink, e.g. the yeast Saccharomyces cerevisiae is used to make bread and beer.
• Lactobacilli bacteria are is used to make yogurt and cheese, as well as naturally found in our gut. However, for people with weakened immune systems, or individuals undergoing cancer treatment, Lactobacilli can sometimes have the opposite effect and make people feel ill.
• Most microbes in food are not harmful to humans, but some microbes on or in food cause illness if food is not cooked thoroughly. Examples of these microbes include Salmonella, E. coli and Campylobacter.

Image taken from Giant Microbes.

Salmonella

(Sam-on-ella)

Image taken from CDC Public Health Image Library.

Campylobacter

(Cam-py-lo-bac-ter)

Watch this clip about Salmonella (2 mins), which provides a brief overview of what causes Salmonella poisoning, and how to minimise risk of contraction.

Watch this clip about Campylobacter (1 min 45 secs), which provides a brief overview of what causes Campylobacter food poisoning, what the symptoms are, and how to minimise the risk of contraction.

A PDF summary of the videos can be found in the downloads section below.

How do microbes grow on food?

Warm, damp conditions are best for microbes to grow on food.

Many dangerous microbes:

• dislike places that are too hot and are killed at temperatures above 70°C.
• multiply very slowly, if at all, at cooler temperatures of 4°C or below.
• can survive being frozen or live at a low temperatures and can start to multiply again if desirable conditions return.

Let us know in the comments – do the children you work with discuss food hygiene at all?