What is food poisoning? It is an acute illness, usually sudden, brought about by eating contaminated or poisonous food. The symptoms of food poisoning are:
Bacteria is the most common form of food poisoning and so it is important that we know more about them. Bacteria are tiny bugs that live in the air, in water, in soil, on and in people, in and on food. Some bacteria causes illness. They are called PATHOGENIC bacteria. Some bacteria cause food to rot and decay, they are called SPOILAGE bacteria. There are four things that bacteria need in order to grow. These are:
Warmth. They love body temperature of 73 degrees but can happily grow at 15 degrees. They grow most readily between 5c and 63c. This is known as the DANGER ZONE
Time. Each bacteria grows by splitting in half. This takes time, on average every 20 minutes. This is known as BINARY FISSION. Imagine, one single bacterium by splitting in half every ten minutes can become more than a million in 3 and a half hours.
Food. They like high protein foods for example, poultry, cooked meat, dairy produce, shellfish, cooked rice, stews and gravies.
Moisture. They need water and most foods have enough water or moisture to let the bacteria thrive.
Some bacteria can form a hard protective case around themselves, this is called a SPORE. This happens when the ‘going gets tough’, when it gets too hot or too dry. So they are able to survive very hot or cold temperatures and can even be present in dried foods. Once the right conditions (5 – 63c) return, the spore comes out of its protective casing and becomes a growing, food poisoning bacteria again.
Bacteria and food poisoning
We have established that the presence of bacteria is one of the most common causes of food poisoning – the presence of poisonous chemicals can also cause food poisoning. There are a number of potentially toxic chemicals present in food. For example, potatoes which have turned green contain the toxic substance, Solanine, which is only dangerous when eaten in excess.
Rhubarb contains Oxalic Acid – the amounts present in the stems which are normally cooked are relatively harmless to humans, but the higher concentration in the leaves makes them very dangerous to eat.
A toxin is a poisonous substance that may be produced by the metabolism of a plant or animal, especially certain bacteria. Toxic food poisoning is mainly caused by Staphylococci in the UK and more rarely in this country, Clostridium Botulinum.
Foods most commonly affected by Staphylococci are:
• Meat pies
• Sliced meats
• Pies with gravy
• Synthetic cream
50-60% of people carry Staphylococci in their noses and throats and are present in nasal secretions following a cold. Staphylococci are also present in skin wounds and infections and find their way into foods via the the hands of an infected food handler. Hence the importance of keeping all wounds and skin conditions covered. Although staphylococci are themselves readily destroyed by thorough cooking or re-heating, the toxin which they produce is often much more heat-resistant and may need a higher temperature or longer cooking time for its complete destruction.
Food poisoning from Clostridium botulinum – known as botulism – is extremely serious. This produces a life-threatening toxin which is the most virulent poison known. Foods most commonly affected by clostridium botulinum are:
• Inadequately processed canned meat, vegetables and fish.
During the commercial canning process, every care is taken to ensure that each part of the food is heated to a high enough temperature to ensure complete destruction of any clostridium botulinum spores that may be present.