1. Food Contamination There are three different types of contaminants:
Physical
Chemical
Bacterial

2. Physical Contamination
Is the presence of foreign bodies
in food:
Eg. Insects
Glass
Packaging material
Objects off the food eg, chicken bones
Parts of the machinery
Food Handler eg. nails, hair, jewellery
To reduce the risk of physical contamination:
Only purchase stock from approved suppliers.
Keep the food covered during storage and preparation.
Keep potential physical contaminants away from food
Chemical Contamination
Can make food / drink poisonous or cause tainting which leads to an unpleasant taste or smell.
Chemical contaminants can be:
Cleaners- used to clean work surfaces.
Copper pots- which can react with the food.
Cans -when open can react with the food.
Aerosols -which should not be used near food or food preparation
surfaces.

3. Bacteria
Bacteria are tiny living creatures often known as “germs”. They are so small that it is impossible to see them without a microscope.
Bacteria are everywhere in:
The soil
Dust and water
The air around us
On our bodies
Most bacteria are harmless and sometimes are even beneficial eg. in yoghurt and cheese making and they can aid digestion in our gut.
Spores
Some kinds of bacterial are capable of forming protective covering called spores.
This protection enables bacteria to remain alive but inactive in situations that would normally kill them.
Later if the conditions become suitable the spores change into the usual form of bacteria that then multiply rapidly.
Spores can withstand high cooking temperatures and are able to survive situations where nutrients or moisture are not immediately available.

4. There are two types of bacteria that can cause a problem: Food spoilage Food Poisoning
Food Spoilage Bacteria
The main signs of food spoilage bacteria are changes in:
Colour
Texture
Smell
Taste
Food displaying any of these signs are unfit to eat and must be discarded immediately.
Food Poisoning Bacteria
Cannot be detected by :
Taste
Smell
Texture
Colour
Therefore dangerous foods can look perfectly normal.
Types of food poisoning bacteria are:
Salmonella – found in eggs, poultry
Staphylococcus aureus – found in ears, nose, throat & wounds.
E. Coli – found in raw meat.
Clostridium perfringens – found in dust, dirt & soil.
Bacteria cannot move on their own they have to be carried on to the food.

5. In order to multiply bacteria needs: Food ,Moisture, Time and Warmth Without all of these bacteria will be unable to multiply to a dangerous levels
Food
Bacteria grow on some foods more easily than on others
There are two groups:
High risk- foods which have a high protein content and contain moisture the main high risk foods are:
Cooked meat and poultry
Cooked meat products eg. gravy, soup and stock.
Milk and egg products.
Shellfish
Cooked rice
Low risk are low in protein and moisture They are foods containing sugar ,salt or acid, such as;
Jams
Pickles

6. Time
Every bacterial cell multiplies by splitting itself into two.
Every 10 to 20 minutes bacteria will double in number therefore within 4 or 5 hours one bacterium will have multiplied to many thousands.
Moisture
To grow bacteria needs moisture.
Bacteria are less likely to survive in dried food, but once moisture is added start to grow.

7. Above 100oC are usually killed 73oC most bacteria will not survive
Warmth
Above 100oC are usually killed
73oC most bacteria will not survive
Some bacteria will be protected by spores & they will come out & multiply.
64 – 72oC bacteria will survive but very few
will multiply. This is the temperature that food
should be kept at before serving.
5oC –63oC Bacteria that causes food poisoning
will grow at these temperatures & grow most at
around 37Oc
0-4oC bacteria multiply very slowly
Below –18oC bacteria are dormant & will not
multiply until they begin to defrost when they
will grow again.
Safe zone
Danger Zone
Safe Zone

8. Stomach ache Nausea Vomiting
Food Poisoning
Food poisoning is an illness people get from eating contaminated food The main symptoms are:
Stomach ache Nausea Vomiting
Diarrhoea Possible fever
Some people are more at risk and these are:
Babies/toddlers- do not have a fully developed immune system dehydrate quickly.
People already ill- less able to fight symptoms.
Elderly – immune system & defence mechanism are poor.
Pregnant women – likely to pass symptoms onto the unborn baby, listeria can be fatal.
The onset of symptoms is usually sudden and may start within 2hours of taking food but there may be an interval of several days. The illness typically lasts1or 2 days but sometimes can continue for a week or more.

9. Name of food poisoning bacteria Which food it is found in.
Symptoms of food
poisoning
How it gets in food
Salmonella
Raw eggs, chicken, dairy foods, salad dressings etc
Severe abdominal pain, diarrhoea,
Nausea, vomiting
Contamination from raw foods, dirty water, pests, people
Staphylococcus aureus
Cooked meat & meat products, poultry, dairy products
Abdominal pain, diarrhoea, nausea, vomiting,
Human nose, mouths, skin, cuts
Untreated milk
Bacillus cereus
Cooked rice, milk & dairy foods meats, starchy products, vegetables
Abdominal pain, watery diarrhoea, vomiting,
Dust, soil
E.coli
Cooked foods, milk, seafood, salad
Abdominal pain, diarrhoea, vomiting, fever
Human sewage, dirty water, raw meat
Clostridium perfringens
Meat & meat products, poultry, gravy, stews
Abdominal pain, diarrhoea
Sewage, soil & dust, animals, insects, raw meat
Listeria
Coleslaw, pate unpasteurised soft cheese cook chill meals
Fever diarrhoea, flu like illness, miscarriage
Sewage, dirty water , soil
Campylobacter
Poultry, milk & milk products
Persistent abdominal pain, diarrhoea often blood, headache
Wild birds, animals. pests, water, sewage