food hygiene
We’re always being told in the news that food poisoning is on the rise, and for good reason. Food poisoning makes people very ill indeed, and this section of the site will explain the basics on how to keep bacteria under control. It’s easy to keep food poisoning in the home to a minimum.
The golden rule is: always keep food cool, clean and covered
Food poisoning is caused by contaminated food and food can be contaminated by:
Bacteria
Viruses
Other poisons
Bacteria
These are small living organisms. A colony of 25,000 could be accommodated on the point of a needle. They might be small but they can be very harmful.
Viruses
Viruses are tiny particles far smaller than bacteria and they only grow on living tissue, so they do not grow in food.
Other Poisons
Occasionally chemical poisons can accidentally infect food, for example from weed killers and insecticides. High acid foods like tomatoes can act on the metal of a cooking vessel causing traces of the metal to enter food.
Poisons can also occur by eating dangerous plants or fungi such as toadstools, certain berries and seeds, or even items like rhubarb leaves or incorrectly cooked kidney beans.
Bacteria
Bacteria need 4 things to grow:
Food
Moisture
Warmth
Time
When the correct amount of these is provided, bacteria multiply. In 20 minutes one bacteria will double. In another 20 minutes those two bacteria will become four. After seven hours that one original bacteria will have increased to 1,048,576 all ready to multiply again in only 20 minutes time to make double that quantity!
Most foods which have a high protein content and are particularly rich in nutrients. They contain moisture and are excellent for bacteria growth. These are known as high risk foods. Examples of these include:
Group |
Examples of foods |
Notes |
Cooked meat and poultry |
Cooked meat products including gravy, soup and stock |
These foods are high in the nutrients bacteria needs to grow. If kept in warm conditions even a small number of bacteria will become many millions in a short time. |
Milk and eggs and foods made |
Milk, eggs, cheese, butter, cream, custard and mayonnaise |
Milk and eggs and foods from them are often involved in food poisoning, usually because they are kept in warm conditions or have been contaminated by a food handler. |
Shellfish |
Mussels, oysters, prawns, crab and lobster |
Shellfish may eat food or live in water that is contaminated; the risk is greatest if eaten raw. |
Cooked rice |
Cooked rice, rice stuffing’s, paella etc |
Bacteria can form spores when in conditions they do not like, eg high temperatures during boiling. When cooled to the correct temperature these spores germinate and start to reproduce again. |
Foods containing sugar, salt or acid discourage growth of bacteria. Some foods have preservatives added to them to stop bacterial growth.
Temperatures
Bacteria that cause food poisoning grow at temperatures between 5˚C and 63˚C. They grow fastest as our body temperature 37˚C. For this reason food should be kept above or below these temperatures. The food hygiene danger zone is between 5˚C and 63˚C.
Best practice
When preparing food, don’t sneeze, cough, scratch your head, pick your nose or smoke. With regards to washing your hands, it is best to be thorough: do so before preparing ingredients, during cooking, after you have handled raw meat etc.
Cross contamination
This is the process where one food contaminates another, eg juices from raw meat getting into other foods. So, it’s best not to store them together - keep raw and cooked foods separate. Also, have separate chopping boards and knives for raw and cooked food and wash them well between each use.
Thermometers
Ensure food is cooked thoroughly before serving, as this ensures all bacteria are dead. When using a digital thermometer, the inside of food will be cooked if it stays at a minimum of 72˚C for 2 minutes. Oh, and always remember to clean the thermometer after you use it.
