There are three main ways in which food can come contaminated, they are:
- can occur at any time of production.
- Includes pieces of metal or plastic entering the food, or things that were supposed to have been removed e.g. pips, stones, stalks etc.
- Pests can also contaminate food with droppings.
- Includes metal residues, pesticides, cleaning materials.
- Careless use of chemicals leads to food contamination.
- Farmers which use pesticides put chemicals in the food.
- Food additive quanities needs to be carefully considered also.
- Food changes durring storage.
- This process can affect the colour, flavour, texture and appearance of food - mostly colour changes are harmless.
- Changes caused by micro-organisms and enzymes.
- Micro-organisms include yeasts, viruses, mould and bacteria.
- Bacteria which are harmful are called Pathogenic bacteria
Food spoilage by Micro-organisms
- Moulds are tiny plants or fungi which grow on the surface of food.
- Produce spores which travel in the air.
- Prefer warm moist conditions.
- Can be used for good e.g. cheese such as stilton.
- Generally mouls are harmless but some contain mycotoxins which can be dangerous.
- Mycotoxins are naturally occurring toxins produced by moulds.
- Do not cause food poisoning but can cause food spoilage.
- Found naturally in environment, and require warm moist conditions to reproduce.
- Yeasts are essential for the production of bread, wine and beer.
- Not usually considered to be a living organism as they consist of genetic material.
- Can cause disease as they destroy living cells.
- Viruses carried around by humans, animals, birds, water and sewage.
- The Hepatitis A virus can be passed on in food thorugh infected food handlers.
- Bacteria are single-celled micro-organisms found in water, air, soil, people and animals.
- They are essential in the production of yoghurt and cheese.
- Probiotic drinks contain 'helpful' bacteria and claim to have health benefits.
- To multiply they require warm, moist, food conditions.
- Spoliage bacteria - this bacteria affects the quality of the food product and sometimes makes it unsafe to eat.
- Pathogenic bacteria - Pathogenic bacteria includes salmonella, staphylococcuss, clostridium.
- Food-borne disease - illnesscaused by eating food contaminated by harmful substances.
- Can be caused by pathogenic bacteria, but also can be caused by viruses, chemicals, and metals contaminating the food substance.
- Can also be contaminated by posionous plants and animals.
- Two ways in which bacteria can make you ill - by eating the live bacteria or eating the toxin they produce.
Eating pathogenic bacteria
- Bacteria enters to stomach and intestine and multiplies, this is how the most common pathogenic bacteria causes illness.
- Some bacteria…