Microorganisms, Spoilage and Food-Poisoning Bacteria
The tiny living things that spoil food and cause food poisoning: bacteria, yeasts and moulds, the conditions they need to grow, high-risk foods, and the five named food-poisoning bacteria.
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The tiny life on food
Food is full of tiny living things called microorganisms: bacteria, yeasts and moulds. Some are useful and help make foods like bread, cheese and yoghurt. Others spoil food or cause food poisoning. This module looks at what microorganisms need to grow, the signs that food has gone off, and the bacteria that make us ill.
Spoilage and bacteria terms
Learn these four terms before you study food safety.
Useful or harmful?
Microorganisms can be helpful in the kitchen or dangerous.
Learn the five precisely
Learn the five named food-poisoning bacteria precisely: campylobacter, E. coli, salmonella, listeria and staphylococcus aureus. Bacteria grow fastest in the danger zone, between about 5 and 63 degrees Celsius, under current food safety guidance. To stay safe, remove one of the conditions bacteria need, for example chilling food to slow their growth.
Match the growth condition
- warmth
- moisture
- food
- time
- bacteria multiply fastest in warm conditions
- bacteria need water to grow
- bacteria need nutrients, so high-protein foods are risky
- given enough of it, a few bacteria become millions
Match the microorganism
- mould in blue cheese
- yeast in bread
- salmonella in raw chicken
- furry mould on old bread
- a useful mould used to make food
- a useful yeast that makes dough rise
- a harmful bacterium that causes food poisoning
- a sign that food has spoiled
What is a high-risk food?
What is a high-risk food?
- A moist food high in protein that bacteria grow on easily and is ready to eat.
- A dry food like biscuits that lasts a long time.
- Any food kept in the freezer.
- Any food that is served hot.
Conditions for growth
Select the TWO conditions that bacteria need to grow.
- Warmth.
- Moisture.
- Bright light.
- A freezer.
How food becomes unsafe
Put the stages of food becoming unsafe in order, earliest first.
- Bacteria land on a warm, moist food
- Over time the bacteria multiply
- The food becomes unsafe to eat
- Eating it can cause food poisoning
Summarise food safety
Bacteria, yeasts and moulds are all _____. To grow, bacteria need warmth, moisture, food and _____. Foods that are moist and high in _____ are called high-risk foods. Some microorganisms are useful, such as the _____ that makes bread rise. Harmful bacteria like salmonella can cause food _____.
Count the bacteria
How many food-poisoning bacteria are named in this module: campylobacter, E. coli, salmonella, listeria and staphylococcus aureus?
Find the high-risk foods
Tap the TWO high-risk foods.
- Cooked chicken
- Dry crackers
- Cooked rice
- Tinned beans
- A bag of sugar
Useful, harmful or spoiled?
Decide what each microorganism is.
- The mould used to give blue cheese its flavour
- Salmonella found in undercooked chicken
- Furry green mould growing on old bread
Keep food safe
Explain how you could stop harmful bacteria growing on a cooked chicken. Use what you know about the conditions bacteria need.
- Name the conditions bacteria need to grow
- Explain how removing one condition stops them
- Explain one other way to keep the food safe