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Food Safety and toxicology

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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
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 Harmful substances in foods
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

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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 Time Moisture Food 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 Bacterial growth After 10 minutes After 20 minutes After 30 minutes

20 From 0 to 1,536,000 in only 80 minutes !!!!!! Time : 9.30 Bacteria : 0
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 Time : Bacteria : 48,000 Time : Bacteria : 96,000 Time : Bacteria : 192,000 Time : Bacteria : 384,000 Time : Bacteria : 768,000 Time : Bacteria : 1.5 million From 0 to 1,536,000 in only 80 minutes !!!!!!

21 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 no multiplication Log Phase Decline Phase Lag Phase Time (hours)

22 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 Cereus Found in soil, vegetation, cereals and spices

23 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)

24 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.

25 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!

26 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

27 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)

28 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

29 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)

30 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.

31 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)

32 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.

33 Clostridium Botulinum
Sources - Fish intestine, soil and vegetables. Common food vehicles – Low acid processed food contaminated after canning or vacuum packing. Smoked fish, bottled vegetables. Onset period –2 hours to 5 days (usually 12 to 36 hours). A heat sensitive neurotoxin produced in the food which affects the nervous system. (Toxic food poisoning)

34 Clostridium Botulinum
Symptoms - Difficulties in swallowing, talking and breathing. Double vision and paralysis. Diarrhoea followed by constipation. Fatalities are common and survivors may take several months to recover. Specific characteristics – Forms spores which produce an exotoxin under anaerobic conditions. Both the spores and toxin will survive normal cooking temperatures. Millions required to cause illness. Bacteria multiply between 3.3°C and 48°C.

35 Staphylococcus aureus
Pathogenic Bacteria Source Symptoms Average Onset Time Raw meat Poultry and eggs Pests and pets Human and animal intestines Dirt and refuse Vomiting Nausea Diarrhoea Abdominal pain hours after eating Salmonella Human nose, throat, ears, skin Septic wounds Animals and raw milk Vomiting Abdominal pain Low temperature Staphylococcus aureus 1 – 7 hours after eating Raw meat and poultry Soil, dirt and refuse Raw vegetables Pests and pets Human and animal intestines Clostridium perfingens Diarrhoea Abdominal pain hours after eating Soil Marine sediment Raw fish and meat Animal intestines Paralysis Breathing and swallowing difficulty Diarrhoea followed by constipation Clostridium botulinum 12 – 36 hours after eating Nausea Vomiting Abdominal pain Diarrhoea 1 - 5 hours or 8 –16 hours depending on the form of the food poisoning Bacillus cereus Dust and soil Cereal, rice and pasta

36 Campylobacter enteritis
Escherichia Coli 0157 Listeriosis That’s the end of lesson 1! Coming next lesson: Foodborne diseases Typhoid and paratyphoid fever Dysentery

37 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

38 Food Safety Keep Hot Food Hot Keep Cold Food Cold
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

39 Food with an “off” appearance or odor should not be used or tasted
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

40 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

41 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

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

43 Some People Face Special Risks Why Some People Face Special Risks
A variety of people may face these special risks: Pregnant women Very young children People with chronic illnesses or weakened immune systems Older adults Why Some People Face Special Risks A variety of people may face these special risks – pregnant women, young children, people with chronic illnesses or weakened immune systems, and older people. Immune systems weaken with age. 43

44 Why Some People Face Special Risks (Continued)
Why Older Adults? Immune systems weaken with age Stomach acid decreases as you get older Diseases/illnesses may further weaken the body Why Some People Face Special Risks (Continued) Stomach acid decreases as you get older. Stomach acid plays an important role in reducing the number of bacteria in our intestinal tracts – and the risk of illness. Underlying illnesses such as diabetes, some cancer treatments, and kidney disease may increase a persons risk of foodborne illness. 44

45 Recognizing Foodborne Illness Recognizing Foodborne Illness
Can’t see, smell or taste bacteria in food Often takes 1 to 3 days to cause illness, but can take up to 6 weeks Recognizing Foodborne Illness It is hard to tell if a food is unsafe, because you can’t see, smell or taste the bacteria it may contain. Usually foodborne bacteria take 1 to 3 days to cause illness. You could become sick anytime from 20 minutes to 6 weeks after eating some food with dangerous bacteria. It depends on a variety of factors, including the type of bacteria in the food. Sometimes foodborne illness is confused with other types of illness. If you get foodborne illness, you might be sick to your stomach, vomit, or have diarrhea. Or, symptoms could be flu-like with a fever, headache, and body aches. The best thing to do is check with your doctor. 45

46 3 Pathogens of Special Importance to Older Adults
Escherichia coli O157:H7 Salmonella Listeria monocytogenes Recognizing Foodborne Illness (Continued) You could become sick anytime from 20 minutes to 6 weeks after eating some food with dangerous bacteria. It depends on a variety of factors, including the type of bacteria in the food. Sometimes foodborne illness is confused with other types of illness. If you get foodborne illness, you might be sick to your stomach, vomit, or have diarrhea. Or, symptoms could be flu-like with a fever, headache, and body aches. The best thing to do is check with your doctor. 46

47 E. coli Lives in intestines of healthy cattle and other ruminant animals. Typical food sources: Undercooked ground meats, Contaminated produce served raw (lettuce, spinach, sprouts), Unpasteurized milk 47

48 Salmonella Salmonella outbreaks have been associated with: Why eggs?
Raw and undercooked eggs Undercooked poultry and meat Raw milk Produce and unpasteurized juice Why eggs? Salmonella can grow both inside the egg and on the outside of shells NOTE: Consumption of undercooked eggs most common risky food behavior among persons > 60 years 48

49 Listeria Bacteria widespread in nature, soil, water
Survives and grows at refrigerator temperatures! Risky Foods: Refrigerated Ready-to-Eat foods (i.e. deli salads, lunch meats, hot dogs, soft cheeses made with raw milk) Listeria is associated with (RTE) refrigerated foods served without further heating If contaminated, Listeria reproduces during long storage time of RTE meat and poultry products Rarely causes disease in healthy non-pregnant persons 49

50 Listeria Almost all cases: elderly, pregnant women and immune-compromised persons Mild gastrointestinal symptoms: 8-48 hrs Invasive illness: 2-6 weeks following exposure Fever, muscle aches, headache, loss of balance, bacteremia, meningitis, encephalitis 20-30% death rate 50

51 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

52 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

53 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

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55 Spore Bacterial cell Spore forming inside cell
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

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

57 Spore forms in cell

58 Cell disintegrates

59 Spore is released

60 Spore starts to germinate

61 Spore continues to germinate

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

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72 From raw materials to consumer:
Chemical, microbiological and technological aspects of food Most of the food is treated in some way to improve its shelf life, texture, palatability or appearance. It would be difficult to change this situation. So, it is important to know what happens to the various food components on the way from raw material to consumer.

73 reduction and prevention of health risks hazardous reaction products
raw materials processing food quality and safety reduction and prevention of health risks hazardous reaction products contaminants Nutrients natural toxins contaminants additives Figure : Food: from raw material to consumer

74 the four categories of food components are discussed in the following order:
natural toxins (including microbial toxins) 2. antinutritives 3. contaminants, 4.food additives and the rationale for their use 5. nutrients.

75 Natural Toxin Endogenous toxins of plant origin
1 Toxic phenolic substances Flavonoids Tannins Coumarin, safrole, and myristicin 2. Cyanogenic glycosides Glucosinolate s 3 Natural contaminants Mixing of edible plants with toxic plants Contamination resulting from intake of toxic substances by animals Contamination of milk with plant toxins Natural toxins in aquatic organisms 4. Microbial toxins Food-borne diseases Bacterial toxins Mycotoxins Aflatoxins Ochratoxin A

76 Antinutritives 3.1 Introduction
3.2 Type A antinutritives (antiproteins) 3.2.1 Protease inhibitors 3.3 Type B antinutritives (antiminerals) 3.3.1 Phytic acid 3.3.2 Oxalic acid 3.3.3 Glucosinolates 3.3.4 Dietary fiber 3.3.5 Gossypol 3.4 Type C antinutritives (antivitamins) 3.4.1 Ascorbic acid oxidase 3.4.2 Antithiamine factors 3.4.3 Antipyridoxine factors

77 Contaminants 4.1 Introduction 4.2 Contamination with heavy metals
4.2.1 Mercury 4.2.2 Lead 4.2.3 Cadmium 4.3 Nitrate 4.4 2,3,7,8-Tetrachlorodibenzo-p-dioxin 4.5 Pesticide residues 4.6 Food contaminants from packaging material

78 Food additives 5.1 Introduction
5.2 Use of food additives in relation to their safety 5.2.1 Colorings 5.2.2 Flavoring agents 5.2.3 Preservatives Antioxidants Antimicrobials Antibrowning agents

79 Nutrients 6.2 Macronutrients 6.2.1 Fats
Undesirable fat components in raw materials Changes in dietary fats during storage and processing of raw materials, and during manufacturing, preparation and storage of food Rancidity Oxidation of fats and oils, and adverse health consequences Effects of processing techniques on the oxidation of dietary fats and oils 6.2.2 Carbohydrates Changes in dietary carbohydrates during manufacturing and storage of food 6.2.3 Proteins Changes in proteins during processing of raw materials, and during manufacturing, preparation and storage of food 6.2.4 Pyrolysis products occurring in food 6.3 Micronutrients 6.3.1 Hypervitaminoses Vitamin A Vitamin D

80 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

81 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

82 Food Poisoning 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)

83 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

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

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