Revision
Topics
1. causes of food spoilage and food poisoning
2. safety and hygiene practices to prevent food spoilage and food poisoning
Food spoilage
What is food spoilage?
Food spoilage can be defined as a disagreeable change in a food's normal state. Such changes can be
detected by smell, taste, touch or sight. These changes are due to a number of reasons: air and
oxygen, moisture, light, microbial growth and temperature.
Food spoilage occurs when the sensory properties of food deteriorate. There are three main causes
of food spoilage:
 Chemical contamination (spoilage).
 Physical contamination (spoilage).
 Microbiological contamination (spoilage)
Chemical contamination
 Occurs when dangerous chemicals contaminate foods.
 These chemicals include pesticides, detergents and naturally occurring poisons such as
found in green potatoes
 Caused by incorrect cleaning of equipment and poor food storage
Physical contamination
 Occurs when non-food objects get into food.
 These objects include glass, hair, insects
 caused by incorrect maintenance and cleaning
Microbial contamination
 Occurs when micro-organisms get into food and poison or spoil it.
 Micro-organisms reduce shelf life
 There are five micro-organisms that live in food:-
1. Yeast
-causes food spoilage in some foods such as fruit juices
-does not cause food poisoning
2. Mould
-visible on food
-Grows in warm, moist conditions
-Some mould can produce poison which can make consumers sick
3.Viruses
-Grow in a living host and some are caught through drinking or eating contaminated water and food
-Hepatitis A is an example of a food borne virus
- Makes consumers sick
4.Protozoa
-parasites found in water contaminated with sewerage
5.Bacteria
There are two types:
-bacteria that sometimes cause food to change colour, texture and flavour
-bacteria that do not change the look, taste or aroma of contaminated food but release
toxins/poisons into the food. These are called food borne pathogens
EG staphylococcus aureus
Salmonellae
E.coli
Bacteria need the following conditions to grow:_
Time
Food (grow on foods high in protein, starch)
PH (foods low in acid eg milk, cheese and meat)
Temperature (between 5 -60 degrees)
Moisture
Oxygen
Remember
The fat poodle took my Oreos
Food poisoning
Food poisoning is an illness that is the result of the consumption of harmful foods. A number of
symptoms occur – these can include: vomiting, diarrhoea and abdominal pains or cramps.
To prevent food poisoning it is important to prevent cross-contamination. It is via crosscontamination that toxic food poisoning is transferred between different food products in a kitchen.
It occurs when there is the transfer of bacteria from a contaminated source to an uncontaminated
source.
1. Complete the table below to explain how each factor contributes to food spoilage.
Factor that results in food
How food spoilage occurs
Food most likely to be affected
spoilage
Air/oxygen
Moisture
Light
Microbial growth
Temperature
2. Explain the role of enzymes in food spoilage.
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3. Develop a list of the similarities between food spoilage and food poisoning.
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4. Develop a list of difference between food spoilage and food poisoning.
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