1. Causes of Food Poisoning Learning Intentions Understand conditions for growth. Understand the different types of food poisoning, bacterial, spores or toxins. Sources, symptoms and control measures.

2. Conditions for Growth • Bacteria is the most common type of food poisoning and is caused by pathogenic bacteria. • They require warmth, food, moisture, time, oxygen and the correct pH level to thrive. • If any one of the above conditions is removed or altered the multiplication of bacterial cells will be hindered. • Bacteria multiply by a process known as binary fission.

3. Binary Fission

4. Warmth • The best temperature for growth of bacteria is 37ᴼC. • The danger zone is 5ᴼC-63ᴼC. • When cooking food it should reach a core temperature of 75ᴼC. • Reheated food must reach a core temperature of 82ᴼC. • Bacteria can multiply slowly at fridge temperature, 0ᴼC-5ᴼC. • No bacteria can grow in a freezer, -18ᴼC but will survive and reproduce on thawing.

5. Food • Like all living cells bacteria need food to grow. • Some foods are high risk foods meaning bacteria can grow easily in them. • They are normally high in protein and moisture and can be eaten without further cooking which would kill off bacteria. • These foods should be kept at a temperature below the danger zone.

6. Moisture • Like all living cells, bacteria need moisture to grow. • Bacteria prefer a high water content; many foods contain sufficient moisture for growth. • Some foods are dried so as to restrict bacterial growth e.g.. Milk and pulses. • When the water is added to these foods bacteria can then begin to grow.

7. Time • Given the correct conditions bacteria will divide into 2 every 10 mins. • It is essential that high risk foods are left in the danger zone (5ᴼC - 63ᴼC) for as short a time as possible.

8. Oxygen • Most bacteria require oxygen to grow. These are called aerobic bacteria. • Some bacteria do not require oxygen to grow. These are called anaerobic bacteria.

9. pH Level • Most bacteria cannot grow in an acid environment of pH 4.7 or less, for example in the pickling method of preservation.

10. Bacteria, Spores and Toxins • Food poisoning can be caused by any of the above. • Some bacteria produce spores these are resistant to high temperatures but cannot multiply. • When conditions for the bacteria return to favourable the spores will release the bacteria which will then continue to multiply. • Some pathogenic bacteria produce a toxin or poison in the food which is difficult to destroy by normal cooking processes.