Intermediate Food Safety

1. Intermediate Food Safety 1st Lesson

2. Aims To explain the causes and effects of food poisoning and its relevance to food safety

3. Objectives By the end of the lesson you should be able to: • Describe the different types of food poisoning • Understand how bacteria cause food poisoning • Identify different pathogenic bacteria and their related symptoms

4. What is Food Hygiene? • The science of preserving health • It involves all measures necessary to ensure the safety and wholesomeness of food during it’s preparation and storage

5. What does it involve? • Rejecting contaminated food • Decontaminating food • Protecting food from contamination through high standards of personal hygiene, cleaning and disinfection • Preventing any organisms multiplying • Destroying any harmful bacteria by thorough cooking • Discarding unfit or contaminated food

6. Normally associated with symptoms such as diarrhoea and vomiting May also include headache, stomach cramps and fever Bacteria are responsible for most cases Other causes include mycotoxins (poisonous chemicals produced by some moulds) Food Poisoning

7. Food Poisoning (contd.) • Physical contamination:- objects falling in to food – metal, glass, packaging materials etc. • Chemical contamination:- Bleach, cleaning chemicals getting in to food • Natural contamination: Poisonous plants and berries, undercooked red kidney beans

8. Poisonous mushroomsThe deathcap – one bite can prove fatal And also…..The deadly Puffer fish!

10. One sliver of it's liver can deliver you to the next life!

11. Most food poisoning is caused by? Bacteria

13. Vulnerable Groups • Food poisoning is more likely to affect people with lowered resistance to disease than healthy people who might show mild symptoms or none at all. • The following are particularly vulnerable to food poisoning: - • Elderly or sick people • Babies • Young children • Pregnant women

14. Types of bacteria • Spoilage: Not particularly harmful bacteria which cause food to go off • Beneficial: “Good Bacteria” which are used to make yoghurt and cheese • Pathogenic: Illness causing bacteria

15. In order to grow and multiply germs need: Warmth Moisture Food Time Remember it like this Too Many Flies Waiting

16. In ideal conditions where there is Moisture, Food and Warmth (37degrees centigrade is ideal), bacteria can double every 10 to 20 minutes. They do this by dividing in to two. This is called Binary Fission

17. These cells are beginning to divide into two

18. After 10 minutes After 20 minutes Bacterial growth After 30 minutes After 40 minutes

19. cooking chicken to a core temperature of 75°C should kill most of the bacteria Time : 9.30 Bacteria : 0 Time : 9.40 Bacteria : 12,000 Time : 9.50 Bacteria : 24,000 Knife contaminated by blood Bacteria : 48,000 Time : 10.00 Bacteria : 96,000 Time : 10.10 Time : 10.20 Bacteria : 192,000 Time : 10.30 Bacteria : 384,000 Time : 10.40 Bacteria : 768,000 Time : 10.50 Bacteria : 1.5 million From 0 to 1,536,000 in only 80 minutes !!!!!!

20. Bacterial Growth Curve Numbers Of Bacteria Numbers of bacteria decrease Stationary Phase rapid multiplication Numbers of bacteria remain constant as the number produced is equal to the number dying Log Phase no multiplication Decline Phase Lag Phase Time (hours)

21. Spore A resting resistant phase of some bacteria (including Clostridium Perfingens and Botulinum and Bacillus Cereus). The bacterium produces a protective coat which helps it to survive high temperatures (up to 120°C) and lack of water. When favourable conditions return, the spores split open and release the bacteria which are then able to grow and multiply Bacterial cell Spore forming inside cell

22. Spore Formation This is what happens ………….. Cell

23. Spore forms in cell

24. Cell disintegrates

25. Spore is released

26. Spore starts to germinate

27. Spore continues to germinate

28. Now see as, in suitable conditions, the cell begins to divide (binary fission)………………………….

37. Toxins Some bacteria release poisons known as toxins which cause food poisoning. Some toxins, known as exotoxins multiply in food. These toxins are not easily destroyed by cooking and may remain in food once they have developed. Other bacteria produce toxins inside the human body only after the food has been eaten. These are called endotoxins

38. Moulds and Yeasts • Moulds are a type of fungi that will grow on most foods and at many temperatures. Some are used in food production such as cheese manufacture. Unwanted moulds usually spoil the food but do not cause food poisoning. • Yeasts are another type of fungi that will grow in food. They are used in making food such as bread and beer but also spoil many foods including jam, fruit juice, yoghurts and meats

39. Food Poisoning bacteria Usually need millions of bacteria to cause illness. The multiplication of bacteria within the food plays an important part in the disease

40. Staphylococcus Aureus Found in human nose and throat (also skin) Clostridium Perfingens Found in animals and birds Salmonella Found in animals, raw poultry and birds Clostridium Botulinum Found in the soil and associated with vegetables and meats Bacillus CereusFound in soil, vegetation, cereals and spices

41. Salmonella • Sources - The intestines of ill people and carriers, animals and animal food, raw meat, raw poultry, raw milk, raw eggs, food pests • Common food vehicles – Undercooked or contaminated cooked meat, raw milk and eggs • Onset period – 6 to 72 hours (usually 12 to 36) Endotoxin in intestine (infective food poisoning)

42. Salmonella • Symptoms - Abdominal pain, diarrhoea, vomiting and fever. Duration is usually one to seven days. • Specific characteristics – Usually requires millions of bacteria to cause illness. Multiplies from 5°C to 47°C under aerobic or anaerobic conditions.

43. Aerobic and Anaerobic • Bacteria which need oxygen to multiply are classed as aerobic • Bacteria which only multiply without oxygen are called anaerobic • Just to confuse you some bacteria including Salmonella, Staphylococcus aureus and Bacillus cereus are classed as facultative anaerobes which means they can multiply with or without oxygen!

44. Salmonella Specific controls • Hygienic farm and abbatoir practices • Avoid cross contamination • Complete thawing of frozen poultry • Thorough cooking to 75°C for one minute • High standards of personal hygiene • Effective cleaning • Safe sewage disposal

45. Clostridium perfingens • Sources - The intestines of humans and animals, faeces and sewage, soil food pests, raw meat and poultry • Common food vehicles – Rolled joints, casseroles, stews, sauces and meat pies when cooking has removed oxygen • Onset period – 8 to 22 hours (usually 12 to 18) Enterotoxin in intestine. (infective food poisoning)

46. Clostridium perfingens • Symptoms - Abdominal pain, diarrhoea, (vomiting is rare) and fever. Duration is usually 12 to 48 hours. • Specific characteristics – Usually requires millions of bacteria to cause illness. Multiplies from 10°C to 52°C under anaerobic conditions. At 46°C it can double every 10 minutes. Produces spores. Illness caused from consuming millions of organisms

47. Staphylococcus Aureus • Sources - Human nose, mouth, skin, hands, spots, boils, septic cuts etc • Common food vehicles – Dairy products. Cold cooked meat and poultry, peeled cooked prawns • Onset period – 1 to 7 hours (usually 12 to 18) Exotoxin produced in food. (Toxic food poisoning)

48. Staphylococcus Aureus • Symptoms - Abdominal pain, diarrhoea, vomiting. Occasionally subnormal temperatures. Duration between 6 and 24 hours. • Specific characteristics – Usually requires millions of bacteria to cause illness. Toxin may survive boiling for up to 30 minutes. Multiplies from 7°C to 48°C under aerobic or anaerobic conditions. Can tolerate relatively high salt content.

49. Bacillus Cereus • Sources - Cereals, especially rice, cornflour, spices, dust and soil • Common food vehicles – Reheated rice, cornflour and spices. • Onset period – 1 to 5 hours. Exotoxin produced in food. (Toxic food poisoning)

50. Bacillus Cereus • Symptoms - Abdominal pain, diarrhoea, vomiting. Occasionally subnormal temperatures. Duration between 12 and 24 hours. • Specific characteristics – Forms spores which produce an exotoxin under aerobic or anaerobic conditions. Both the spores and toxin will survive normal cooking temperatures. Millions required to cause illness. Bacteria multiply between 7°C and 48°C.