Safe Food Handling 1 Notes Ch1

1. INTRODUCTION TO FOOD HYGIENE AND SAFETY What is food hygiene and food safety? • Food Hygiene-all sanitary measures, principles and procedures put in place to ensure that food is free from agents of contamination or disease germs in any form. • Food safety-The process of handling, preparation and storage of food in ways that prevent food-borne infection/illness.  Food quality control. It is the procedures that a company must follow to ensure that its products meet food quality regulations and acceptable standards to ensure consumer safety.  Toxicity is the capacity of a substance to produce harm or injury of any kind under any conditions.  Hazard is the relative probability that harm or injury will result when substance is not used in a prescribed manner and quantity  Food infection /Food Poisoning results from ingestion of live pathogenic organisms which multiply in the body and cause disease  Food intoxication: Some bacteria produce harmful toxins which are present in food even if pathogen has been killed Toxins in food cannot be detected by smell, appearance or taste. Hence foods which smell and appear good are not necessarily safe.  Adulteration: Food adulteration is the process in which the quality of food is lowered either by the addition of inferior quality material or by extraction of valuable ingredient  Contamination: It is the presence of harmful, or objectionable foreign substances in food such as chemicals, micro-organisms, dilutants before/during or after processing or storage FOOD HYGIENE INVOLVES • • preventing the spread of infection by people who handle food. ensuring that food preparation areas, equipment and surfaces are clean. AIMS OF FOOD HYGIENE • • • Protect food from risks of contamination. Prevent bacteria from multiplying to levels resulting in ill-health. Destroy bacteria in food through adequate cooking or processing. THE BENEFITS OF FOOD HYGIENE • • • • • Return of business through satisfied customers. Good reputation. Compliance with the law. High quality food and increased shelf life of food. Good working environment for staff, boosting staff morale and job satisfaction. THE COST OF POOR HYGIENE • • • • • • • Food poisoning outbreaks and sometimes death. Customer complaints. Wastage of goods due to spoilage. Pest infection. Suspension of trading by local health authorities. Fines and cost of legal action by food poisoning sufferers. Loss of reputation through word of mouth or media exposure. . Key considerations in food safety ( basics of food safety notes) 1. Keep a clean food preparation and serving utensils, and environment 2. Separate raw and cooked 3. Cook Food thoroughly 4. Keep food at safe temperatures 5. Hand washing at all times 6. Use safe water and raw materials SOURCES OF CONTAMINATION • • • • • • People - (hands, mouth, nose, anus, skin). Clothes. Utensils - (dirty utensils, especially those used for raw then cooked foods without adequate cleaning and sanitising in between, tea towels). Raw foods - (especially red meat, chicken, seafood, vegetables, water). Flies and pests. Garbage. PREVENTION If we are to adopt the main principles of food hygiene we must adhere to the following practices. • Develop and maintain high standards of personal hygiene. • Avoid cross-contamination of foods. • Establish and maintain correct storage conditions. • Clean and sanitise all utensils and equipment used in the handling and preparation of food. • Control pests. AGENCIES RESPONSIBLE FOR FOOD SAFETY AND HYGIENE IN KENYA/INSTITUTIONAL FRAMEWORK            In Kenya, the responsibility for coordinating the multiple institutions (agencies) involved in food safety management rests on many agencies. Food safety control agencies operate under the Ministries of Trade, Industrialization, Public Health and Sanitation, Livestock, Fisheries Development, and Agriculture. A summary of the legal and policy framework of these agencies and the implementing mechanisms for the laws is documented by FAO/WHO, 2005 [5]. The agencies include Kenya Bureau of Standards (KEBS), Kenya Agricultural Research Institute (KARI), Kenya Plant Health Inspectorate Services (KEPHIS), Department of Public Health (DPH), Weights and Measures Department (WMD), Government Chemist's Department, Department of Veterinary Services (DVS), Kenya Dairy Board (KDB) ,and Horticultural Crops Development Authority (HCDA), among others Kenya meat commission NATIONAL LEGISLATIONS RELATING TO FOOD SAFETY/ LEGAL FRAMEWORK 1. animal health 2. public health act 3. fisheries act 4. food drugs, and chemicals substances act 5. dairy act 6. veterinary act 7. meat control act 8. agricultural produce(export) act 9. Kenya Meat Commission act 10. water act etc Food Standards Effective food standards and control systems are required to integrate quality into every aspect of food production and service, to ensure the supply of hygienic, wholesome food as well as to facilitate trade within and between nations. There are four levels of standards which are well coordinated. a. Company Standards: These are prepared by a Company for its own use. Normally, they are copies of National Standards. b. National Standards: These are issued by the national standards body, c. Regional Standards: Regional groups with similar geographical, climate, etc. have legislation standardisation bodies. d. International Standards: The International Organisation for Standardisation (ISO) and Codex Alimentarius Commission (CAC) publish international standards. 1. Codex Alimentarius Commission( refer food safety notes) CAC is an intergovernmental body formed with the objective of establishing international standards to protect the health of the consumers food and agricultural trade. In 2017, the membership of Codex was 187 member countries and one Member Organisation (European Community)respectively. India is a member through the Ministry of Health and Family Welfare. CAC has become the single most important international reference point for developments associated with food standards. The document published by the CAC is Codex Alimentarius which means ‘Food Code’ and is a collection of internationally adopted Food Standards. The document includes Standards, Codes of Practice, Guidelines and other recommendations inorder to protect consumers and ensure fair practices in food trade. Different countries use Codex Standards to develop national standards 2. International Organisation for Standardisation (ISO) The International Organisation for Standardisation (ISO) is a worldwide,non-governmental federation of national standards bodies (ISO member bodies). The mission of ISO is to promote the development of standardization and related activities in the world with a view to facilitate the international exchange of goods and services, and to develop cooperation in the spheres of intellectual, scientific, technological and economic activity. 3. World Trade Organisation (WTO) WTO was established in 1995. The main objective of WTO is to help trade flow smoothly, freely, fairly and predictably, by administering trade agreements, settling trade disputes, assisting countries in trade policy issues. The WTO Agreement covers goods, services and intellectual property. The DPH under the minizstry of health safeguards the health of consumers through food safety and quality control, surveillance, prevention and control of food borne diseases/illnesses The Minister constitutes the boards under DPH that oversee the enforcement of the basic laws for food safety namely: Central Board of Health – (Food, Drugs and Chemical Substances Act, Chapter 254) [17], and, Public Health Standards Board – (Public Health Act, Chapter 242) 2. PERSONAL HYGIENE WHY FOOD HYGIENE? Food hygiene is concerned with every aspect of food production. The main aim is to promote health. This is the responsibility of everyone in the food industry, from managers to cleaners. All must take great care when it comes to handling and preparing food to prevent unnecessary waste of food, due to spoilage or contamination by moulds, bacteria, physical damage or vermin. Most people think that food hygiene is simply common sense, they try to do the right thing and they certainly do not set out to poison anyone. However, when you work in the food industry you must consider a number of important issues to do with your approach to personal hygiene and kitchen hygiene. WHERE DOES GOOD HYGIENE BEGIN? PERSONAL HYGIENE One of the keys to safe food is good personal hygiene of the people who prepare and serve it. The bacteria that can cause food poisoning can easily transfer from the hands and clothes of the people who handle it to food, so it is important that everyone who handles food has high levels of personal hygiene. As well as hands, clothes and other body parts, hair and jewellery can contain and spread bacteria to food. Important, too is the health of the people handling food. People with illnesses and those with wounds like cuts and scratches can spread illness through food without knowing it. Good hygiene begins with the attitudes and knowledge of all food service workers. It starts with personal hygiene and caring for yourself. The outward signs are a healthy body and attention to grooming. PERSONAL HYGIENE AND CONSCIOUS BODY HABITS As a food service worker you are responsible for: 1. Practising personal cleanliness: • having a bath or shower daily. • wearing clean undergarments daily. • using a deodorant but avoid the use of overpowering perfumes. • washing hair regularly. • shaving at least daily, for males without beards. • beards, if worn, should also be washed daily and kept trim. • cleaning teeth frequently to ensure oral hygiene and fresh breath. • keeping fingernails clean, neat and well trimmed. Nail polish should not be worn when preparing food. 2. Preparing yourself systematically for work: • brush hair and secure it off the face and in such a way that hair will not contact food or surfaces used for preparing food. • wear clothing which will not cause contamination of foods. • do not smoke in food preparation or serving areas. • wash hands and fingernails thoroughly before commencing work. This is vital because hands are the major contact between the food handler and food. • wear a clean apron. • wear limited jewellery, plain band type rings and plain sleeper style earrings. PERSONAL HYGIENE AND UNCONSCIOUS BODY HABITS Following these fundamental rules for good personal hygiene ensures basic standards. However, a food handler also needs to be aware of unconscious body habits and must avoid actions such as scratching or rubbing the head, nose or other body parts, stroking hair/beards, picking pimples, licking fingers when tasting food and the like. Ordinarily, these unconscious body habits do not create problems, but when handling foods for the public, it is not only unprofessional behaviour but is potentially dangerous. THE FOOD HANDLER AS A SOURCE OF HARMFUL BACTERIA All this focus on the cleanliness of the food handler is because the human body provides a rich environment for microorganisms to live in. Micro-organisms (eg. bacteria) are to be found in and on the body. Most of these bacteria are harmless. Many even have an important role to play in maintaining health. (eg. gut bacteria manufacturing Vitamin K). However some are harmful and can cause food poisoning. Apparently healthy people may be carrying pathogenic bacteria without showing any signs of illness. Everyone has to assume that they may be carrying food poisoning bacteria and so take precautions against spreading the disease. It is estimated that 50% of the population carry Staphylococcus Aureus in their mouths/noses. Staph Aureus may also be present in infected cuts and pimples. This food poisoning bacteria may be spread to food by a food handler coughing or sneezing over food, tasting food using fingers or working with an infected cut. Salmonella and Clostridium perfringens can be present in the intestine of seemingly healthy people. Inadequate washing of hands after going to the toilet may result in faecal material being transferred to the food. If healthy people are carrying bacteria, then people suffering from nose, throat or chest infections, intestinal upset or skin infections will be shedding bacteria at an even greater rate. If you are sick you should not handle food. Report any abnormal health conditions. Keep cuts or burns covered with a clean waterproof dressing. HAND-WASHING Always wash your hands before handling food. Washing hands is not just a quick wetting under the tap. Adequate washing of hands involves these steps: • Using the hand basin, wet hands with hot water. • Apply soap. Lather and thoroughly rub over hands, wrists and fingers. A nail brush is useful. • • • Continue washing action for sixty seconds. Rinse under warm, running water. Dry using disposable paper towel. Wash your hands again: • after visiting the toilet. • after handling raw food. • after using a tissue, coughing or sneezing. • after handling garbage. • after changing a nappy. • after handling pets or other animals. • after smoking or touching your hair or other body parts. 3. BASIC MICROBIOLOGY MICRO-ORGANISMS A micro-organism is any living organism so small that, on its own, it is invisible. Individual micro-organisms can only be seen with the aid of a microscope. The micro-organisms of most concern in food service are: • Viruses. • Bacteria. • Yeasts. • Moulds. Micro-organisms can be found everywhere in our environment - they are on us, in the air, soil and water. The effects of micro-organisms can be desirable or undesirable. BENEFICIAL MICRO-ORGANISMS These micro-organisms can play a crucial role in: • the breakdown of dead plant and animal matter. • the production of certain foods such as microbial action in yoghurt, cheese, bread, wine. • the production of some antibiotics eg penicillin. SPOILAGE MICRO-ORGANISMS These micro-organisms alter the appearance, texture, flavour and odour of food, making the food undesirable to eat. Consumption of spoiled food such as sour milk, does not result in illness or disease. PATHOGENS Less than 1% of all micro-organisms are harmful and produce disease. These are referred to as pathogens eg. viruses, food poisoning bacteria. VIRUSES Viruses are the smallest of all micro-organisms. Viruses do not have their own cellular structure, and to become active must enter a living cell. Once a virus enters a host cell, it redirects the activities of that cell towards reproducing itself. Viruses are always pathogenic but are host specific ie. animal cells are only susceptible to animal viruses. Most viral diseases affecting people are transmitted by contact eg measles, mumps, H.I.V., colds and influenza. However, a few viral infections are transmitted by contaminated food or water. Both Hepatitis A and viral gastro-enteritis are food borne. Healthy humans produce antibodies, as a defence in response to invading viruses. Once exposed to a virus, either through an attack of the disease or artificially through vaccination, immunity is conferred. BACTERIA Bacteria are single cell organisms and their name gives a clue to their shape. Bacteria are important for the ageing of meat and in producing foods such as cheese, yoghurt, sour cream, sauerkraut, pickled cucumbers, salami, peperoni and vinegar. Sometimes bacteria spoil food. Slime and 'off' smells indicate their action. Other bacteria can cause food poisoning eg. Salmonella. Regardless of their shape, bacteria have the same internal structure and reproduce in the same way. It reproduces by the one cell dividing into two parts. This is called binary fission. Under ideal conditions binary fission can be completed in 15-20 minutes. This means that a single bacteria can multiply to large numbers in a relatively short time. Under ideal conditions, bacterial population can grow from one thousand to over four million in under four hours. Between one and two million bacteria form a serious food poisoning threat. Under adverse conditions, growth slows down, and many bacteria die. Bacillus and Clostridium have a special way of coping with adverse conditions. They form spores which is a protective means of survival. They go into a dormant state until conditions become favourable again. They are not killed by freezing or boiling while in this 'protective' state. YEASTS Yeasts are single celled organisms, larger than bacteria. Yeasts reproduce by a process called budding. A small growth appears on the 'mother' cell. As this bulge grows, the mother cell progressively cuts off the new 'daughter' cell. The daughter cell is about half the size of the original cell. It will increase in size until it is ready to 'bud' or reproduce. Yeasts breakdown sugars to produce carbon dioxide and alcohol. This reaction is utilised in the production of alcoholic beverages and bread. MOULDS Moulds are usually multicellular but each cell is capable of growing independently. Moulds are often quite visible. They appear in various forms such as powdery blue-green-white patches on lemons, white fluffy patches on tomato paste or blackened areas along the rubber lining on refrigerator doors. Moulds consist of fine thread-like strands called hyphae. The hyphae grow in a mass either across the surface or down through the medium. UNDESIRABLE EFFECTS OF MOULDS Many foods such as pumpkin, citrus fruits, zucchini and bread are susceptible to mould spoilage. Some moulds are pathogenic and can cause infections of the skin eg tinea and ringworm. A few moulds produce dangerous toxins. These are of concern in the bulk storage of peanuts and grains. It produces a toxin called aflatoxin. Long term consumption of aflatoxin causes liver cancer. DESIRABLE APPLICATION OF MOULDS Moulds are responsible for the particular flavours and textures of the blue vein cheeses and the surface ripened cheeses, brie and camembert. A highly prized sweet dessert wine is made with grapes affected by a particular mould. Moulds and yeasts are the microscopic members of the fungi group. Larger fungi, mushrooms and truffles are also used extensively as foods. Environmentally, moulds are important because of their ability to change complex organic materials into simple substances eg the rotting and decay of dead matter. Medically, moulds are significant for their antibiotic properties eg. Penicillium mould producing Penicillin. 4. FACTORS AFFECTING MICROBIAL GROWTH Micro-organisms form an invisible world around us. They are in the air, on us, on food, equipment and food preparation surfaces. It would be difficult to find an environment free of micro-organisms. In some situations microbial growth will be encouraged eg. in the making of yoghurt or bread. At other times their presence will be actively discouraged eg. taking precautions to prevent food poisoning. Either way, to understand how to control micro-organisms, the food worker needs to have some basic knowledge of the conditions required for microbial growth. There are six factors required for the growth of micro-organisms: 1. Suitable food. 2. Suitable water. 3. Suitable temperature. 4. Suitable oxygen levels. 5. Suitable pH. 6. Time. SUITABLE FOOD Micro-organisms exhibit a wide variation of nutrient requirements. Some can be sustained on inorganic material. However, the bacteria responsible for food poisoning thrive well in the foods we like to eat, especially those high in protein, high in moisture and not very acidic. SUITABLE WATER • • • • • Micro-organisms need liquid water for growth and multiplication. Dried foods will not support microbial growth providing they are kept dry, and tend to be spoiled by yeasts and moulds. The majority of microbes will not grow in high sugar foods. Freezing makes water unavailable to micro-organisms. Food is not the only aspect of a kitchen environment that may supply moisture for microbial growth. Soiled, wet tea-towels, dish cloths, and mops, as well as improperly dried items of small equipment provide suitable breeding grounds for micro-organisms. SUITABLE TEMPERATURE Micro-organisms vary in their temperature requirements. Some thrive at low temperatures eg. Listeria Monocytogenes, while others can live at higher temperatures. Pasteurisation will destroy pathogenic bacteria , but not spoilage bacteria in milk. Bacterial spores can survive boiling. Each micro-organism has an optimum temperature for growth. Below a minimum temperature growth is halted, although the microbe does not necessarily die. Above a maximum temperature the microbe is likely to be destroyed. Bacteria that cause food poisoning grow well at the temperature between 4°C and 60°C. This is called the TEMPERATURE DANGER ZONE. The temperatures in a commercial kitchen fall within the Temperature Danger Zone. Food should not be kept long in the Temperature Danger Zone. • Cold foods are to be kept below 4°C. • Hot foods are to be kept above 60°C. This refers to the internal or core temperature of the food. SUITABLE OXYGEN LEVELS • • • • • Most microbes are aerobes i.e. need oxygen for respiration. Anaerobes do not use oxygen, and will not grow in the presence of it. A small group of bacteria are capable of growing in either aerobic or anaerobic conditions and are called facultative. All moulds are aerobic, which explains why they grow on the surface of foods. Yeasts are facultative. SUITABLE PH • • Bacteria prefer neutral or slightly acidic environments. Moulds and yeasts tolerate quite acidic environments. SUITABLE TIME Given optimal conditions micro-organisms can reproduce rapidly. Bacteria are the fastest growing microbes. Growth relates to increase in numbers, not size. Micro-organisms need time to multiply enough to cause food poisoning or serious spoilage of food. 5. FOOD SPOILAGE (refer food hygienep4 notes) Food spoilage may be due to three separate but inter-related factors: PHYSICAL SPOILAGE • • • • Damage to the protective surface layer of a food item eg. cracked egg shell, dented cans, insect or rodent damage to packages. This increases the chance of chemical and/or microbial spoilage. Moisture loss eg. wilted leafy vegetables, freezer burn on incorrectly packaged frozen goods, staling of bread. Moisture gain eg. staling of biscuits. Aroma loss eg. ground coffee. • • Odour absorption eg. fruit salad prepared on board used previously for crushing garlic. Presence of undesirable objects eg. stone in a packet of lentils, fish hook in canned fish. CHEMICAL SPOILAGE • • • Chemical contamination eg. cleaning substances improperly removed from surfaces or equipment. Enzyme action eg. browning or ripening of fruit Rancidity of fats and oils. MICROBIAL SPOILAGE The action of bacteria, yeasts and moulds is the major cause of food spoilage. When present in large numbers their activity is easy to detect. The appearance of the food is altered. There might be colour changes, visible whiskery growth, surface slime, softening of texture, off odours and off flavours. How do these microbes get on to food? Contamination occurs through contact with soil, air, water, equipment, packaging materials and food handlers. To keep the microbial population small, care must be given to personal hygiene, the cleanliness of the premises and equipment and proper storage conditions and times. Otherwise microbial growth is encouraged and foods spoil faster. BACTERIA Bacteria spoil food rapidly. Foods that support bacterial growth include meats, fish, poultry, milk and many vegetables. Often the food becomes slimy and develops an unpleasant odour. Bacteria require high levels of moisture, thus do not spoil dry foods. To minimise bacterial growth keep food surfaces as dry as possible when storing. Foods that are acidic are less susceptible to bacterial spoilage. Also store foods out of the temperature danger zone. Ensure that cold foods are kept cold, and hot foods are kept hot. YEASTS Yeasts spoil foods that are acidic and high in sugar, such as jams, fruit, juices, syrups and alcoholic beverages. The product may develop a beery smell and show signs of gas bubbles. Yeasts grow well in warm, moist environments. Low temperatures inhibit their growth, while heating above 60°C will destroy them. MOULDS Moulds are aerobic so they first appear as whiskery patches on the surface of the foods. Their mycelium will however spread down into the food. Moulds are slow growing and favour moist, slightly acidic foods, such as fruits, some vegetables and bread. Mould affected food has a musty odour. Cold, dry conditions inhibit mould growth. FOOD PRESERVATION Food preservation is a form of processing of food to prevent it from spoilage and making it possible to store in a fit condition for future use. To minimise or prevent food spoilage the growth of micro-organisms must be inhibited. This can be achieved by altering one or more of the conditions necessary for microbial growth. Food preservation techniques are based on this principle. Let us now learn about the principles of food preservation: 1. By killing the micro-organisms. boiling milk 2. By preventing or delaying the action of micro-organisms.eg lowering or rising temperatures, covering the food or packaging 3. By stopping the action of enzymes.eg heat treatment , blanching METHODS OF PRESERVATION (refer food preservation notes) DEHYDRATION Controlled condition: water. Heat is applied to evaporate the moisture. Bacteria can survive the drying process. Care must be taken with some rehydrated products. Once water is added, powdered milk must be treated as fresh milk. • Sun drying - tomatoes, sultanas. • Air drying in heated chambers - apples, bananas. • Spray drying - used for liquids - milk, eggs, instant coffee. • Roller drying - used for tomato paste, instant mashed potato and breakfast cereals. • Tunnel drying - used for vegetables. • Freeze drying - meat, instant coffee, instant meals. SALTING Controlled condition: water. In low concentration, salt binds with the moisture in the food thus making the water unavailable to microbes. At higher concentration salt will dehydrate the microbial cells. • • Brines – olives. Cures - salt in combination with potassium nitrate and potassium nitrite eg. corned beef, bacon. THE ADDITION OF SUGAR Controlled condition: water. • Sugar acts in the same way as salt -syrups, jams, glace fruits, candied fruits, crystallized fruits. PASTEURISATION Controlled condition: temperature. In this process heating destroys pathogens, but does not destroy spoilage organisms or bacterial spores. UHT - ULTRA HIGH TEMPERATURE Controlled condition: temperature. Product is heated to 132°C for two seconds, then cooled to below 4°C. The item is sterilised. All micro-organisms, both spoilage and pathogenic are destroyed. Examples include long life milk, fruit juices specially packed. Refrigeration is not required until opening. CANNING Controlled condition: temperature. In this process, heat is used to destroy Clostridium Botulinium spores. The times and temperatures used in canning may vary depending on the acidity of the food. In the standard method, food is cooked in the can. For larger cans the food may be heat treated first, then canned. FREEZING Controlled condition: temperature and water. At -18°C the growth rate of micro-organisms is severely reduced. The low temperature inhibits growth and water in the frozen state is not available for microbial growth. Note. Micro-organisms are not necessarily destroyed by freezing. Some may survive and can become active once the food is thawed. VACUUM PACKAGING Controlled condition: oxygen. Oxygen is withdrawn. A special plastic packaging is used. Anaerobic micro-organisms survive. Examples include vacuum packaged meats, fish, cheese. These foods must be held at refrigeration temperatures. Items such as coffee beans can be stored at room temperature. CONTROLLED ATMOSPHERE Controlled condition: oxygen and temperature. Oxygen levels are reduced and carbon dioxide levels are increased. Temperatures are kept low. Examples include pears and apples which can be stored for many months under controlled atmospheric conditions. Further ripening is suspended, thus deterioration is slowed too. PICKLING Controlled condition: pH. Vinegar is most often used to change the pH of foods. Examples include pickled vegetables. SMOKING Smoke contains anti-microbial substances formaldehyde and cresol. Nowadays, smoking is most often used for flavour, not primarily for preservation. CHEMICAL PRESERVATIVES These are anti-microbial substances. Certain additives are used to control the growth of undesirable bacteria, yeasts and moulds. Examples. • propionic acid used as a mould inhibitor in bread. • sulphur dioxide effective against bacteria, yeasts and moulds and used in dried fruits and peeled potatoes. • nitrates and nitrites used to cure meats to control Clostridium botulinium. Controlling one or more conditions required for the growth of micro-organisms slows the rate of food spoilage. 6. FOOD POISONING Foods that are spoiled look, smell and taste 'off'. These are detectable signs to warn the consumer not to eat them. Eating spoiled foods however is unlikely to cause illness. On the other hand, foods that are contaminated with harmful micro-organisms or toxins look, smell and taste okay. Toxins in foods can be from a number of sources. Some foods are naturally poisonous or are subject to natural contaminants. Examples: • Poisonous mushrooms. • 'green' potatoes - poison 'solanine'. • Comfrey - contains a poisonous alkaloid. • Rhubarb leaves - high levels of oxalic acid. • Apricot kernels - contain cyanide. • Apple seeds - contain cyanide. • Peanuts - may be contaminated with high levels of Aspergillus flavus mould. CHEMICAL FOOD POISONING Harmful chemicals may end up in the food supply as a result of agricultural practices or industrial pollution. Pesticides/herbicides are widely used in the control of undesirable plants and insects. The surface of fruits and vegetables may have spray residues. It is good practice to wash fruit and vegetables before use. Sometimes cleaning chemicals can accidentally contaminate food eg. sodium hypochlorite inadequately rinsed from drink containers. Always store chemicals away from food. Make sure chemicals are correctly labelled. Always follow manufacturer's instructions for use. BACTERIAL FOOD POISONING The term food poisoning is used to describe the illness that results from the consumption of food containing pathogenic bacteria. Symptoms of food poisoning vary but usually involve vomiting, diarrhoea and abdominal pain. The bacteria responsible for food poisoning may be derived from: • Contaminated raw ingredients. • Infected food handlers. • Pests contaminating raw or processed foods. • The equipment, surfaces and utensils in the food preparation area. The growth of these bacteria can be accelerated by: • Preparing food too far in advance. • Inadequate cooking. • Inadequate reheating. • Improper thawing. • Improper hot holding of cooked foods. Most food poisoning is the result of unhygienic practices. The causes of food poisoning are sometimes summarised as the Food Poisoning Chain. There are six links. source of bacteria bacteria transferred to food food, pH, moisture, oxygen conditions time and temperature contaminated food is eaten food poisoning Breaking any link in the chain will prevent food poisoning. source of bacteria no transfer making conditions of food, moisture, pH & oxygen unsuitable for bacterial growth time & temperature food is safe to eat no food poisoning Food service workers should organise their work so that the links in the food poisoning chain are broken. They should be especially careful when handling potentially hazardous foods. These foods are high in protein and moisture and will readily support bacterial growth eg. meats, poultry, fish, milk and eggs. The most important types of food illnesses are caused by the following: These bacteria cause infection Illness is due to toxins produced by the bacteria Salmonella Listeria monocytogens Clostridium botulinum Vibrio parahaemolyticus Staphylococcus Aureus Campylobacter jejuni Bacillus Cere SALMONELLA Incubation time: 8-48 hours. Diarrhoea, vomiting, abdominal pain, fever. Symptoms: Lasts: 1-7 days. ENVIRONMENTAL AND FOOD SOURCE • • • • • • • Present in the intestines of animals. Spread by flies, cockroaches, mice and rats. Meats, poultry and eggs contaminated with excreta during processing. Shellfish and fish from sewerage polluted waters. Vegetables grown using animal manure. Transferred from raw foods to cooked foods by hands, equipment and surfaces in the kitchen. food handlers can be carriers of Salmonella. CONTROLS • • • • • Thorough cooking of foods. Temperatures above 65°C will destroy Salmonella. Wash hands and equipment between handling raw and cooked foods. Wash vegetables, especially those to be eaten raw. Enforce strict personal hygiene. Avoid cross contamination after cooking by keeping raw and cooked meat apart. CLOSTRIDIUM PERFRINGENS It is anaerobic and forms spores. ILLNESS Incubation time: 8-20 hours. Diarrhoea and abdominal pain. Vomiting is rare. Symptoms: Lasts: 12-48 hours. Occurs particularly in situations of large scale catering. ENVIRONMENTAL AND FOOD SOURCES • • • • Present in the intestines of animals, commonly found on meat and poultry. Spores occur widely in soil, dust, air and water. Vegetables contaminated with animal manure, soil or dust may harbour spores. Large quantity meat dishes that involve long slow cooking and roasts that are cooked ahead, then reheated. Spores may survive the cooking process. If cooling is slow and not under refrigeration, spores may germinate and Clostridium Perfringens bacteria grow to dangerous numbers. CONTROLS • • Keep soil carrying vegetables out of preparation area. Avoid partial cooking of foods, then reheating. • • • Cool cooked meat dishes quickly (within 1½hours) and refrigerate. If foods must be reheated, do it quickly and thoroughly. Enforce strict personal hygiene. LISTERIA MONOCYTOGENES The organism responsible for listeriosis has caused several major food-borne outbreaks affecting particular at-risk groups in the community. The bacteria can be found in a variety of ready-to-eat foods such as deli-meat, cooked diced chicken, smoked mussels, smoked fish, pre-prepared salads and soft serve ice-cream. It has also been found in unpasteurised milk, soft cheese, coleslaw and pate. WHO IS AT RISK FROM LISTERIA INFECTION? Listeria infection can affect people differently. Healthy people may develop few or no symptoms. However, for some people, the infection can be serious enough to require hospitilisation and be a threat to life. People who are at particular risk of infection include: • Pregnant women and their unborn babies. • Newborn babies. • The elderly. • Anyone whose immune system has been weakened by disease or illness eg cancer, leukemia, diabetes, liver or kidney disease. • Anyone on prednisone or cortisone as this can also suppress the immune system. SYMPTOMS Healthy people may not be affected at all. In persons at risk, symptoms may include fever, headache, tiredness, aches and pains. These symptoms may progress to more serious forms of the illness, such as meningitis and septicaemia. Less common symptoms are diarrhoea, nausea and abdominal cramps. In pregnant women the illness may vary from a mild form to resulting in miscarriage, still birth, premature birth or a very ill baby. How common is Listeria Infection? It is relatively uncommon but the fatality rate among at-risk people is very high. Between 8-24 cases are reported each year. Can Listeria infection be treated? Yes, with antibiotics if treatment is started early. How can you avoid Listeria Infections? As Listeria bacteria are commonly found in the environment, they are impossible to eradicate. Some exposure to the bacteria is unavoidable; most people are, however, at low risk of Listeria infection. HIGH RISK FOODS • • • • • • Ready to eat seafood such as smoked fish and smoked mussels. Pre-mixed raw vegetable salads, such as coleslaw. Pre-cooked meat products which are eaten without further cooking or heating, such as pate, sliced deli-meat, and cooked diced chicken. Any unpasteurised milk or foods made from unpasteurised milk. Soft serve ice-cream. Soft cheeses such as brie, camembert, ricotta. SAFE FOODS • • • • All freshly cooked foods. Hard cheeses, cheese spreads, processed cheeses. Milk, freshly pasteurised and UHT. Yoghurt. • Tinned and pickled foods. BACILLUS CEREUS Bacillus organisms are aerobic and spore forming. In the vegetative state they produce toxins. Infective dose is large; 100 million bacteria. Illness Incubation time: Symptoms: Lasts: 1-12 hours. Vomiting, some diarrhoea and abdominal pain. 6-24 hours. ENVIRONMENTAL AND FOOD SOURCES • • • Found in soil, dust and water. Frequently present in rice, cornflour, dried peas and beans. Mostly associated with spore germination in cooked foods incorrectly stored and reheated. CONTROLS • • • • Hold food out of the temperature danger zone. Discard water used for soaking dried peas and beans. Refrigerate leftovers quickly. Thoroughly reheat leftovers. SATHYLOCOCCUS AUREUS Staphyle is from the Greek, meaning 'bunch of grapes'. Under the microscope this bacteria looks like a bunch of grapes. Staphylococcus is a facultative micro-organism and able to survive without oxygen. It does not form spores, but does release heat resistant toxin. The bacteria themselves are easily destroyed by heating. The toxin, however may survive boiling temperatures for thirty minutes. Staphylococcus is tolerant of salt. Approximately 50% of the human population permanently or intermittently carry Staphylococcus Aureus in the nose, throat and on the skin. It is the micro-organism which infects pimples, cuts and burns. Illness Incubation time: 2-6 hours. Acute vomiting, abdominal cramps and sometimes diarrhoea. Symptoms: Lasts: 2-24 hours. ENVIRONMENTAL AND FOOD SOURCES • • • • • • Food handled with contaminated hands. Food handler coughing or sneezing over food. Ham, cold meats, sausages. Bakery items eg. cream filled cakes, trifles, custards. Salads eg. pasta, potato. Unpasteurised milk from cows with infected udders. CONTROLS Enforce strict personal hygiene. Food handlers with colds should not work with food. Use gloves, tongs, spoons to minimise contacting food with bare hands when mixing, slicing, serving. Store food items under refrigeration. guard against cross contamination. CLOSTRIDIUM BOTULINIUM The word 'Botulinium' is a Latin derivative of sausage. Through the ages, sausages have need associated with the most deadly form of bacterial food poisoning. A 0.2mg dose of the toxin produced by the bacteria is thought to be lethal to an adult. Fortunately, botulism is rare and an anti-toxin is available. Clostridium botulinium is anaerobic and forms spores. Illness Incubation time: Symptoms. 12-36 hours Toxins act on the central nervous system. Vision and speech are impaired. Respiratory muscles are paralysed. In the worst cases breathing stops ENVIRONMENTAL AND FOOD SOURCES • • • Found in soil, sea water. Low acid canned foods that have been inadequately heat processed eg. beetroot, corn, beans, mushrooms, fish. Vacuum packed fish eaten raw. CONTROLS • • • Do not use defective ‘blown’ canned foods. Ensure sufficient time/temperature combinations in cookery. Add acid (vinegar, lemon juice, wine) to low acid foods bottled on the premises. CASE STUDY In a local community house the Council provides a lunchtime meal service for the elderly people. On most days, custard is served with the dessert. As it is easy to prepare, the new kitchen assistant is given this task. She starts work at 8.00am and on this particular morning decides to prepare the custard first. At 8.30am she leaves the custard to cool and begins other preparation. Suddenly she wonders if she added the sugar. She tastes the custard with a spoon and thinks it is sweet enough, but checks again just in case, using the same spoon without washing it. Satisfied that the sugar has been added the custard is left on the bench in the kitchen for the rest of the morning. At 12.15pm the custard is gently warmed and then served at 12.30pm with apple crumble. By afternoon tea time several people have started to vomit and have severe abdominal pain. That evening all the people who had eaten custard are ill. 7. FOOD HYGIENE AND FOOD STORAGE Food hygiene is about protecting food from contamination and minimising microbial growth. The many ways that food may be exposed to cross contamination are shown below. Insect and rodent pests Domestic pets Food handler Raw food FOOD Garbage Utensils, equipment and surfaces Soil/ air/water/dust borne contaminants CROSS CONTAMINATION OF FOOD Food hygiene is important at each stage of the catering cycle; that is throughout: • Purchasing. • Transport and delivery. • Receiving. • Storage. • Preparation. Foods should only be purchased from reputable suppliers who follow all the appropriate rules and regulations to ensure that food is wholesome and clean. The transport of food should comply with government regulations. Delivery times should be arranged so that a responsible person can be on hand to receive incoming items. Deliveries such as bread and milk should not be left outside the premises. Items should be checked to ensure that they: • Meet specifications and are of appropriate quality and quantity. • Are not spoiled or damaged. • Are at correct temperatures and that frozen foods are still frozen. CLASSIFICATION OF FOODS FOR STORAGE These groups are based on the stability of foods in terms of expected storage or shelf life. This is relative since all foods are perishable if incorrectly stored. Storing under appropriate conditions will maximise shelf life. NON PERISHABLE • • • Low moisture and low fat eg. flour, sugar, pasta, rice, cocoa, dried peas and beans. Most canned and bottled goods. May be stored at room temperature (18°C) for relatively long periods. SEMI-PERISHABLE • • • Items still low in moisture, but containing more fat. Keep quite well for 1-3 months at room temperature (18°C) eg. snack foods, potato crisps, pretzels, deep frying compound, biscuits. Keeping qualities of some items may be improved if held under refrigeration temperatures eg. eggs, nuts, butter, margarine, firm cheeses. PERISHABLE • • • The quality of these goods deteriorates rapidly at room temperature. Shelf life of between 2-10 days eg. meats, poultry, fish, shellfish, milk, cream, fresh and soft cheese, breads, fruits, most vegetables, cooked foods, products made with eggs or stock. A sub-group within the perishable category is the potentially hazardous foods. POTENTIALLY HAZARDOUS FOODS These require special temperatures 1-3°C • Fresh meat. 0°C • Poultry • Fish, shellfish. 0°C on crushed ice 2-8°C • Small goods • Dairy products 4-8°c STORAGE OF FOOD When storing food, the aim is to protect food from contamination and to minimise microbial growth. Appropriate storage conditions help to maximise quality and minimise wastage due to deterioration and spoilage. There are certain conditions common to dry stores, cool-rooms and freezers critical to the minimisation of food spoilage and the prevention of food poisoning. CLEANLINESS • • • Regular cleaning of floors and shelving. Spillages cleaned immediately. Containers clean, with lids if necessary. SEGREGATION OF DIFFERENT TYPES OF FOOD • • • • Stored at appropriate temperatures. Keep items covered if appropriate. Orderly arrangement of items. Cleaning materials to be kept away from food. PURCHASE APPROPRIATE AMOUNTS • • Over stocking means that items are kept longer in storage. Quality deteriorates, wastage may occur. ROTATION OF STOCK - FIRST IN, FIRST OUT • • Regular inspections for damaged, deteriorating items. Store only for the appropriate time. DRY STORES • • • • • • • • • • • • Cool and protected from sunlight. Well ventilated, dry, free from dampness and humidity. Enough shelving for stacking goods. Orderly arrangements, so frequently used items are accessible. Items should be stored off the floor. Heavy items should be stored on lower shelves. Large bins used for bulk items like flour and sugar. Suitable containers with tight fitting lids used for opened packages such as custard powder and salt. Containers should be clearly labelled. Good lighting to enable easy inspection and cleaning. Dry goods should be monitored for signs of insect infestation or the presence of rodents. Dispose of any rusted, dented, leaking or bulging cans. REFRIGERATOR / COOL-ROOM STORAGE • • • • • Do not overload refrigerator or cool-room. Keep separate sections for different foods. In particular meats, poultry, fish, milk, fruits and vegetables should be segregated. Raw and ready to eat products should be kept well apart. Ready to eat products should always be stored above raw items Place food items on trays or in containers. Do not place food directly on shelves. Do not stack food containers/trays on top of other foods. Cover or wrap foods to prevent contamination, spread of odours, and dehydration. Note: large pieces of meat are best left uncovered. This allows the surface to dry out, slowing down bacterial growth. Keep refrigerator/cool-room door closed when not in use. FREEZER STORAGE • Promptly store frozen foods. • • • • • • Food should be packaged or wrapped to protect items from freezer burn and to prevent spillages. Items should be labelled and dated. First in, first out. Only freeze good quality food. Do not re-freeze thawed products. Minimise opening of freezer to conserve cold air.