Food Safety and toxicology

1. Food Safety and toxicology

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

3. Basically, food is a mixture of chemicals. Usually, food components are distinguished in four categories: 1.nutrients, 2. toxins of natural origin, 3. contaminants, 4. and additives. The nutritients account for more than 99.9% of the food. The main classes of nutrients are : carbohydrates, proteins, fats, vitamins, and minerals, and all of them may pose toxicological risks to the consumer.

4. Food Borne diseases Poisoning Infections Chemical poisoning intoxication enterotoxigenic invasive poisonous poisonous microbial intoxications Plant tissue animal tissue Algae toxins mycotoxins bacterial toxins toxic metabolites Enterotoxins neurotoxins interactions with carbohydrate metabolism

5. What are Food-Borne Diseases? People get sick with a food-borne disease when they consume foods or beverages contaminated with disease-causing microbes, chemicals, insects or other harmful substances. Bacteria, viruses and parasites cause most of these diseases. Toxins, poisons and chemicals can also contaminate food and cause illness.

6. Food Safety Harmful substances in foods Pathogens Bacteria, viruses, parasites Some common pathogens causing foodborne illness Staphylococcus aureus, Clostridium botulinum, Salmonella, Escherichia coli Chemical contamination Pesticides Animal drugs Pollutants Natural toxins Methyl mercury Poisonous plants Solanine

7. Perceived Risk from Food:% Viewing as a Serious Hazard

8. Major social impact of food borne disease… Lost productivity time Days work/school Financial impact Risk of mortality Risk of transmission to family and others

9. The Food Pathogen Problem Estimates of foodborne disease in U.S./yr: 6.5 to 33 MILLION foodborne illnesses Up to 9,000 deaths Hospitalization costs -- > $3 billion Lost productivity -- > $9 billion Under-reported! Adapted from: Council for Agricultural Science and Technology. Foodborne Pathogens: Risks and Consequences, 1994.

10. FDAs Rank of Areas of Concern Most Dangerous Microbial food illness Naturally occurring toxins in foods Residues in foods Environmental contaminants Pesticides Animal drugs, such as hormones, antibiotics Food processing and nutrients in foods Least Dangerous Intentional Food Additives Genetic modification of foods

11. Most food poisoning is caused by? Bacteria

14. Microbes and Food Safety Symptoms of foodborne illness Diarrhea of more than 3 days’ duration Fever of longer than 24 hours duration Headache accompanied by muscle stiffness and fever Numbness, muscle weakness, tingling sensations in the skin Rapid heart rate, fainting, dizziness Majority of food-poisoning cases Result of errors consumers make in handling foods after purchase Commercially prepared food is “usually” safe

15. Food Safety Raw meats can contain live, disease-causing organisms Thorough cooking makes them safe In the mid-1990s a fast-food restaurant chain in the Northwest served undercooked hamburgers from meat contaminated with bacterium E. coli 0157:H7 4 people died 100s of patrons became seriously ill As a result more Government Inspections and Industry controls were set up through the Hazard Analysis Critical Control Point (HACCP) plan

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

17. 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

18. These cells are beginning to divide into two

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

20. 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 !!!!!!

21. Bacterial Food Poisoning • Because harmful microorganisms are present everywhere in the environment, any food can become contaminated if not properly handled before consumption.

22. Many foodborne pathogens are ubiquitous in nature and generally found in soil, water, animals and plants. Pathogens are introduced into a processing plant through the raw materials. Humans and plant equipment may also bring the organisms to a plant. Recontamination of processed food also frequently occurs and contributes to foodborne outbreaks and illnesses. Pathogens can survive for prolonged period on inanimate objects and serve as a source.

23. 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)

24. When considering a product safety, it is important to know the type of microorganisms or toxins likely to be present, their numbers, and concentrations. In addition, their response to the heat (heat-labile or heat-stable), pH, salts, and other processing conditions is important to consider.

25. The numbers and types of microorganisms present in a finished food product are influenced by : • the original source of the food • microbiological quality the raw or unprocessed • sanitary conditions • the conditions for subsequent packaging, handling, storage, and distribution.

26. Fig. 19-4, p. 669

27. Bacteria and Temperature 100 HIGH Campylobacter Cl botulinum A&B Bacteria die if heatedfor a sufficient time. The longer the time, the greater the destruction MinimumGrowthTemp. Staph aureus E. coli Salmonella Cl perfringens Cl botulinum E Bacillus cereus 63 Listeria 40 LOW 38 LOW HIGH Bacteria grow Bacteria Grow at slower rate Heat resistance Bacteria grow quickly • Pathogenic bacteria grow best at human body temperature 37ºC. However the majority will grow between 15-45ºC • Non-sporing cells of bacteria are killed attemperatures above 60ºC. The length of timeranges depending on the organism • Boiling kills living cells, but will not kill allbacterial spores • Fridges should be set below 5ºC. Some bacteriasuch as Listeria monocytogenes can growat refrigeration temperatures 36 15 7 Bacteria stop growing, but do not die 4 0

28. Food Safety Food can provide ideal conditions for bacteria to thrive or produce toxins Disease-causing bacteria require Warmth 40°F - 140°F = 4°C - 60°C Moisture Nutrients To control bacteria Keep hot food hot-above 140F Keep cold food cold-below 40F/4C Keep raw foods separate Keep your hands and the kitchen clean

29. Food Safety Keep Hot Food Hot Keep cooked foods at 140°F or higher until served cooking does not destroy all bacterial toxins If handled improperly can cause illness Cooked foods should be refrigerated immediately or within two hours at the maximum Keep Cold Food Cold Start when you leave the grocery store At home, put foods into the refrigerator or freezer immediately When defrosting foods Thaw meats or poultry in the refrigerator Marinate meats in the refrigerator

30. Food Safety Food with an “off” appearance or odor should not be used or tasted Keep raw foods separate /Prevent cross-contamination Raw foods, especially meats, eggs and seafood, are likely to contain bacteria Keep the raw foods and their juices away from ready-to-eat foods After handling raw foods wash surfaces & your hands, thoroughly with soap Foods prone to microbial growth Those high in moisture and nutrients Those chopped or ground like meats and poultry

31. Foods That Make People Sick Eggs Raw, unpasteurized eggs are likely to be contaminated by Salmonella bacteria Raw pasteurized egg substitutes may contain a few live bacteria They may not be safe for pregnant women, the elderly, the very young, or those suffering from immune disorders Raw Produce Fruits and vegetables are a microbial threat unless they are thoroughly rinsed in running cold water Ten years ago, meats, eggs, and seafood posed the greatest foodborne illness threat Today produce equals them

32. Know the Potentially Hazardous Foods Preparing and serving safe food is important to your customers. Be careful when you work with and prepare foods that are “potentially hazardous.” These are foods that have been linked to foodborne illness Examples of potentially hazardous food are: Meat, poultry and fish Milk and egg products Salads and sandwiches made with meat Sliced melons and sprouts Cooked vegetables, cooked rice or beans

33. You are responsible for identifying “potentially hazardous” foods. Click below to reveal the “potentially hazardous” foods. Potentially Hazardous

34. Contaminated irrigation or flood water Untreated manure Human/animal feces Contaminated seeds

35. 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

36. The diseases caused by foodborne pathogens can be classified into three forms: foodborne infection foodborne intoxication foodborne toxicoinfection

37. Toxic bacterial food poisoning • some bacteria grow in food and produce a toxin within the food which is then consumed e.g. Bacillus cereus and Staphylococcus aureus. When the food is consumed viable cells of the bacteria do not need to be present.

38. Other microorganisms in food may produce harmful or deadly toxins while growing in the intestinal tract e.g. Clostridium perfringens, enterotoxigenic Escherichia coli and enterohaemorrhagic E. coli

39. Infective bacterial food poisoninginfections occur when pathogens are ingested via contaminated food and the bacteria is established in the body, usually growing inside the intestinal tract and irritating intestines e.g. Salmonella spp. and Campylobacter jejuni. The infection may involve subsequent growth in other tissues

40. Intoxication Ingestion of preformed toxins such as staphylococcal enterotoxin, botulinum toxin, Bacillus cereus toxin, and seafood toxins results in food poisoning or Intoxication. Microorganisms present in foods will grow under favorable conditions and produce toxins in the food.

41. Following ingestion, Toxins are absorbed through the gastrointestinal epithelial lining and cause local tissue damage and may induce inflammation resulting in diarrhea or vomiting. In some cases, toxins are translocated to distant organs or tissues such as liver, kidney, peripheral, or central nervous system where they can cause damage.

42. Toxicoinfection Some bacteria cause toxicoinfection, which occurs when ingested bacteria first colonize the mucosal surface and then produce exotoxins in the intestine. Toxins can induce toxic effects on the local cells or tissues and in some cases toxins enter blood stream and induce disease. Examples include cholera toxin produced by V. cholerae; Clostridium produces hydrolytic enzymes such as lecithinase (breaks down lecithin), hyaluronidase and protease (break down extracellular matrix and disrupts tissue structure)

43. 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

45. There are many types of exotoxins and they are grouped based on the structure and the mode of action Membrane-disrupting toxin (pore forming): These toxins either insert into the membrane to cause pore formation (example, hemolysin) A–B type toxin: These types of toxins have two subunits; A and B. B binds to cell receptor and A exerts enzymatic activity such as inhibition of protein synthesis or cleavage of target protein. Proteases: Some toxins (i.e., neurotoxins) inactivate metalloproteases (Zinc metalloprotease) action, thereby interfering with nerve impulses.

46. Table Characteristics of bacterial toxins

47. (i) A-B type toxin receptor Binding B A Toxin Enzymatic action (ii) Pore-forming hemolysin (iii) Membrane active enzyme Phospholipase cleaves phosphatidylcholine(PC)

49. 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)

50. 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.