Microorganisms in Food
Name one food product that uses microorganisms in production.
Any correct answer, including beer, cheese, bread, yoghurt, wine etc.
To kill microorganisms/bacteria that could be harmful.
What are the molecules that cause milk to be naturally creamy?
What causes food spoilage?
Microbial or bacterial action.
Which type of food storage slows down bacterial growth, but does NOT kill bacteria.
Refridgeration.
Which microorganism is used in bread making?
Yeast
What temperature is milk heated to during pasteurisation?
72oC
What sort of pressure is needed in the homogenisation process?
High pressure.
Which bacterium causes the most common type of food poisoning?
Campylobacter
What is the process where yeast produce ethanol when beer or wine is made?
Fermentation
How long does milk need to be at the required temperature for during pasteurisation?
15 seconds.
Why do dairy companies homogenise milk?
To distribute the fat more evenly for a better taste.
Describe how salmonella can be caught.
Why does drying food (e.g. dried pasta) help to preserve it?
Water is removed so bacteria cannot digest and absorb the food source.
What is the substance bacteria act on in yoghurt production and what do they convert this into.
Lactose; converted into lactic acid.
What needs to happen to the milk after it has been at the required temperature for the correct amount of time?
It must be cooled to approximately 3oC.
What is the process called where most or some of the fat is removed from milk?
Skimming.
Describe the effect of low temperatures on bacterial growth.
Growth is slow at low temperatures because there is not enough energy for bacteria to grow quickly.
What is pickling and why does this preserve food?
Placing the food into an acidic substance (vinegar). This lowers the pH so the microbes are inactivated.
What is the word equation for fermentation?
Glucose ----> Ethanol + Carbon dioxide
Why is it important that the milk does not boil during the pasteurisation process?
Boiling would spoil the flavour of the milk.
Define what homogenisation is.
Pumping milk at high pressure through narrow tubes in order to break down fat globules in milk. These will then stay suspended in the milk rather than floating to the top.
Explain why high temperatures are needed when cooking foods like chicken.
The high temperatures kill any bacteria present in the food.
Describe how to prevent cross contamination in food preparation areas.
Don't allow raw and cooked food to come into contact with each other. Store raw and cooked food separately. Use different knives/chopping boards to prepare raw and cooked foods.