A Food Safety For Food Workers Information Source

The intention of food safety is to prevent food poisoning, (the transmission of disease through food) and to maintain the wholesomeness of the food product through all stages of processing, until it is finally eaten.

In the private home where food is prepared for a small number of people the results of food contamination are restricted.
However, food contaminated in a restaurant kitchen for example, can result in a large number of people being affected.

The presence of food spoilage bacteria, taints or foreign material, may not cause food poisoning, but can still result in considerable loss if the product cannot be used.

This booklet provides basic information on micro-organisms and on food poisoning and how to prevent it, to help you, the foodworker, produce a cleaner, safer product.

FOOD SAFETY

• Protecting food from the risk of contamination, including harmful bacteria, poisons and foreign objects.
• Preventing any bacteria present in the food multiplying to a level that would result in food poisoning, or the early spoilage of the food.
• Destroying any harmful bacteria in the food by thorough cooking or processing.

FOOD SAFETY EDUCATION

All food handlers MUST receive adequate food safety education and training that ensures -

• they are aware of the dangers of poor food handling,
• they have the knowledge to break the chain of events that results in food poisoning.

• how the job is done,
• why it should be done,

HIGH RISK FOODS

• All cooked meat and poultry.
• Cooked meat products including gravy, stock, and roll/sandwich fillings.
• Milk, cream, artificial cream, custards and dairy products.
• Cooked eggs and products made with eggs, eg. mayonnaise.
• Shellfish and other seafood.
• Cooked rice.

FOOD POISONING AND SPREAD OF DISEASE

The micro-organisms responsible for illness are bacteria, viruses and fungi, commonly called "germs: or "bugs". But illness can also be caused by chemical contaminants (such as heavy metals), toxins produced by the growth of some micro-organisms (eg. Staphylococci bacteria) and by a variety of organic substances that may be present naturally in foods (such as certain mushrooms and some seafood).

Generally food poisoning results from contamination of food and the subsequent growth of food poisoning micro-organisms.
Food poisoning outbreaks are often recognised by the sudden onset of illness within a short period of time among many individuals who have eaten or drunk one or more foods in common.
Single cases are difficult to identify unless, as in Botulism for example, there are distinct symptoms.

Food poisoning may be one of the most common causes of acute illness; yet cases and outbreaks are generally under-recognised and under-reported.

BACTERIA

Most bacteria are harmless and some are helpful, like those that change milk into cheese or yoghurt. But others cause food spoilage and some known as pathogens are harmful and can cause illness and sometimes death.

The number of bacteria present in food may be used to determine whether or not the food has been handled correctly.

The diseases that are spread by bacteria that enter the body in food, can multiply at an amazing rate when they are provided with warmth and moisture, (especially at room temperature).

Our food can become an ideal home for them.

BACTERIAL CONTAMINATION (VEHICLES AND ROUTES)

• The people present in the workplace and their clothing.
• Other food that is already contaminated.
• Dirty kitchen or work premises and equipment.
• Insects and vermin.

Indirect contamination using an intermediate vehicle is the most common, eg.- the movement of bacteria from the intestine of a food handler to food via their hands, after using the toilet.

Where contamination is passed from raw food to high risk food via for example, a cutting board, this is known as Cross Contamination.

The path that bacteria use to move from the source to the food, is known as the Route.

COMMON FOOD POISONING ILLNESSES

SALMONELLA
Foods involved	Contaminated meat and meat products, especially poultry. Custard, cream, milk and egg products, and salads.
Main Symptoms	Fever, headache, aching limbs, abdominal pain, nausea, diarrhoea, and sometimes vomiting.
Onset of Illness	6 to 72 hours (usually 12 to 36 hours).
Source	Salmonella bacteria are often present in the waste of man and animals, (especially rodents and poultry). This illness is infectious and can be spread to other people.

STAPHYLOCOCCUS
Foods involved	Contaminated moist protein foods. Meat, eggs and fish products.
Main Symptoms	Abdominal pain, severe vomiting, diarrhoea, abdominal cramps, and sometimes collapse.
Onset of Illness	1 to 6 hours (usually 2 to 4 hours).
Source	Staphylococcal bacteria may come from infected sores, nasal secretions and skin (perspiration and hair). The toxin that causes illness can survive ordinary cooking.

CAMPYLOBACTER
Foods involved	Contaminated meat and meat products, especially poultry. Contaminated water, and raw milk.
Main Symptoms	Diarrhoea, abdominal pain, fever, nausea, and vomiting.
Onset of Illness	1 to 10 days (usually 3 to 5 days).
Source	Campylobacter bacteria are often present in the waste of man and animals (especially domestic animals and poultry). This illness is infectious and can be spread to other people.

CHEMICAL POISONING
Foods involved	All foods can be affected; (eg. soap powders/rat poison getting into dry food mixes; garden poison residues in soft drink bottles).
Main Symptoms	Abdominal pain, nausea, at times vomiting and diarrhoea. These symptoms may not be present for a lot of poisons-- in these cases often the first symptom is of collapse.
Onset of Illness	Usually less than half an hour.

Other food-borne diseases of note are Listeria, Yersinia and Cryptosporidium.

LISTERIA
Foods involved	Contaminated processed meats and meat products, raw milk, seafood, poultry and vegetables etc (eg coleslaw).
Main Symptoms	Normal host	Acute/mild fever, influenza-like symptoms.
	At risk host	Fever, intense headache, nausea, meningeal irritation and vomiting. Infection of the foetus, septicemia, meningitis, and still-birth.
Onset of Illness	3 days to 3 weeks.
Source	Listeria bacteria are commonly found in soil, water, vegetation, domestic animals, and man. The illness, though infectious, is relatively rare.
At Risk Hosts	Pregnant women, the elderly, and those with lowered immune systems.

YERSINIA
Foods involved	Contaminated meat and meat products, especially pork mince and tongue. Contaminated water, seafood and raw milk.
Main Symptoms	Under 5 yrs diarrhoea, (sometimes bloody). Over 5yrs abdominal pain (like appendicitis), also fever, joint pain sore throat and rash.
Onset of Illness	12 hrs to 11 days (usually 24 to 48 hours).
Source	Yersinia bacteria are often present in the waste of farm animals (especially pigs) and infected pets-(puppies and kittens) and man. This illness is infectious and can be spread to other people.

CRYPTOSPORIDIUM
Foods involved	Contaminated food and water, unpasteurised milk or fruit juices.
Main Symptoms	Diarrhoea (often watery), abdominal cramps/pain, and anorexia. Fever, nausea, and vomiting occur less often.
Onset of Illness	1 to 12 days (usually 7 days).
Source	Cryptosporidium parasites are often present in the waste of farm animals, poultry, pets and man. This illness is infectious and can be spread to other people.

THE TEN MAIN REASONS FOR FOOD POISONING

1. Inadequate cooling/refrigeration, food left at room temperature.
2. Too long between preparation and consumption.
3. Inadequate reheating.
4. Inadequate cooking.
5. Cross-contamination from raw to high risk/ready to eat foods.
6. Infected food handlers.
7. Inadequate hot holding temperatures.
8. Inadequate hand washing.
9. Contaminated raw foods and ingredients.
10. Improper cleaning of equipment and utensils.

PREVENTION OF FOOD POISONING

THE FOOD POISONING CHAIN

There are three main ways of breaking the food poisoning chain -

• Protecting food from contamination.
• Preventing any bacteria present in the food from multiplying.
• Destroying those bacteria that are present in the food.

PROTECTING FOOD FROM CONTAMINATION BY -

• Inspecting all food and washing fruit and vegetables before preparation.
• Separating raw and high risk/ready to eat foods at all stages of preparation, storage, display and distribution.
  The same equipment, utensils and working surfaces must not be used to handle raw and high risk/ready to eat foods.
• Only handling food when unavoidable.
  Gloves, tongs and other utensils, plates and trays should be used in preference to hands, (but must be washed or changed frequently).
• Keeping food covered as much as possible.
• Preventing insects, animals and birds from entering food rooms.
• Not using unsuitable, defective, or dirty equipment.
• Using good personal hygiene practices - always.
• Not coughing or sneezing over or around food.
• Not handling the food contact surfaces of crockery, cutlery or utensils.
• All food handlers wearing suitable protective clothing.
• Using the correct cleaning procedures.
• Promptly removing unfit or waste food and refuse from food areas.

PREVENTING ANY BACTERIA WITHIN FOOD FROM MULTIPLYING BY -

• Keeping high risk foods at temperatures that inhibit the growth of bacteria (ie. out of the danger zone). Food should be kept below 4°C in a refrigerated unit, or above 70°C in a suitable warming unit.
• Ensuring that during preparation, food is in the danger zone for as short a time as possible. High risk foods must not be left sitting out at room temperature.
• Using suitable preservatives such as salt and sugar.
• Using various packing methods like gas flushing or vacuum packing.
• Not allowing dried foods to absorb moisture.

DESTROYING THOSE BACTERIA WITHIN FOOD BY -

• Adequately cooking food, ensuring that a minimum internal cooking temperature of 80°C is reached.
• Heat processing such as pasteurisation, sterilisation or canning.

PERSONAL HYGIENE

• Hands must be washed before and after handling food.
• If unwell, do not handle food until cleared by a doctor.
• The hair, nose and mouth must not be touched during food preparation.
• Suitable light coloured protective clothing should be worn.
• Cuts and abrasions should be covered with waterproof bandages and if on the hands suitable gloves worn.
• Rings and other jewellery should not be worn as they can harbour dirt and bacteria and could themselves fall into the food being prepared.

FOOD SPOILAGE

The signs that food is spoiling are:

ODOUR - "off odours" are smells (sometimes like rotten eggs) that are produced when bacteria break down the protein in food, (usually fatty foods). This process is called putrefaction.
Taints due to flavour change may also occur.

SLIMINESS - Food becomes slimy as the bacterial population grows.
Moulds may also form slimy whiskers.

DISCOLOURATION - Foods can become discoloured by microbial growth.
Some moulds have coloured spores that give the food a distinctive colour, for example, black pin mould on bread, or blue and green mould on citrus fruit and cheese.

SOURING - Foods go sour when certain bacteria produce acids. A common example is when milk sours from the production of lactic acid.

GAS - Bacteria and yeasts often produce gaseous by-products that can affect food. You may have noticed meat becoming spongy, or packages and cans swelling or having a popping or fizzing sound on opening.

MICRO-ORGANISMS

• At temperatures between -7 to around 70°C.
• Over a pH range from 0 to 11.
• In the presence or absence of oxygen.
• At water activities above about 0.6.

The three main groups of concern are -

• Bacteria
• Viruses
• Fungi (yeasts / moulds)

They are single cell organisms usually having a definite outer envelope or capsule for protection. They multiply by dividing into two, which can occur very quickly, (eg. every 20 minutes). They can actively move and some link themselves together in chains or in bunches.
To resist harm, some bacteria can form spores (tough reproductive cells that are able to survive under adverse conditions), that can resist damage by heat (as in cooking), by cold (as in freezing) and by chemicals such as disinfectants. A spore can survive in dust, on vegetation and in soil for weeks, months or even years until it finds itself in a suitable environment for growth.

VIRUSES

YEASTS
Yeasts are single cell organisms much larger than bacteria and can be found in the soil, on plants and on the skin and body of man. They multiply by forming offspring as buds which grow and then detach themselves.

Some can produce disease, some cause skin infections in man and others cause diseases in plants. Some yeasts spoil food, but beneficial uses are in the making of beer, wine and bread.

MOULDS
Moulds grow as single cell filaments that can branch together making a strongly knit structure like a mat, that can often be seen with the naked eye. Usually they look fluffy, being a familiar sight on foods like jam, cheese and bread. They multiply by producing clusters of dry spores which are blown by the air like seeds.

Many moulds spoil food and a few can cause disease in plants and man, but beneficial uses are in the ripening of cheeses and production of antibiotics.

GROWTH OF MICRO-ORGANISMS

Anything less than optimum conditions will lead to a slowing down or a stopping of growth and then possibly their death.

TIME

TEMPERATURE RELATIONSHIP TO GROWTH AND DESTRUCTION OF BACTERIA

pH

Low pH generally inhibits microbial growth.
Yeasts and moulds are the most capable of growth at low pH.
Other acid-producing bacteria such as lactic acid bacteria also predominate at low pH.

Approximate pH Growth Ranges for some Food-borne Illness Causing Micro-Organisms

WATER

WATER ACTIVITY (a_w)
It is now generally accepted that the water requirements of micro-organisms should be defined in terms of the water activity (a_w) in the environment. This is a measure of the availability of water to micro-organisms for metabolism (the processes of life). The (a_w) of pure water is 1.00, - a 22% salt solution has an (a_w) of 0.86 and a saturated salt solution is 0.75. The (a_w) value for most fresh foods is above 0.99.

AVAILABILITY OF OXYGEN
Micro-organisms respire. That is, they get energy by breaking down chemicals, usually sugars, inside the cell.
Aerobic organisms must use oxygen obtained from their environment (usually air) before they can produce energy for life and growth. Anaerobic organisms can produce this energy only in the absence of oxygen. Facultative organisms can respire in either aerobic or anaerobic conditions.

OXYGEN TENSION
This is the availability of oxygen to micro-organisms, and can be controlled by packaging, eg. by gas flushing.

CONTROL OF MICRO-ORGANISMS

• The spread of disease and infection.
• The spoilage of foodstuffs.
• Contamination of food.

Some bacteria, and almost all virus, yeast and mould cells are killed by a temperature of 60°C for 10 to 20 minutes.

Yeast and mould spores, and most other bacteria are destroyed at temperatures between 70 - 100°C for 5 to 10 minutes exposure.

Bacterial spores however, are very difficult to destroy. Some for example, need at least 10 minutes at 100 to 120°C.

The following terms are commonly used in cleaning -

• Sterilisation - The process of destroying or removing all microbial life.
• Disinfection - The killing of disease causing bacteria as well as other living micro-organisms, but not usually bacterial spores.
  Disinfection does not necessarily kill all micro-organisms, but reduces them to a level not usually harmful to health. In this group are the fungicides (kills fungi), bactericides (kills bacteria) and virucides (kills viruses).
• Sanitising - A term meaning that an article or surface is visibly clean and is free of disease producing organisms.

IMPORTANT TEMPERATURES IN FOOD SAFETY

QUALITY CONTROL

Quality control generally involves inspections of three kinds -

• Raw materials
• Materials in process
• Finished product

FOOD SAFETY PROGRAMMES

HAZARD ANALYSIS CRITICAL CONTROL POINT- (HACCP)

Setting up a HACCP system will involve the following -

• Set up a HACCP team - of those people who fully understand the product.
• Draw up flow charts - that define all stages in the preparation process, from raw materials through to consumption or sale.
• Identify all potential hazards - (eg. physical, chemical, bacterial) etc.
• Identify the critical control points - consider all preventive measures and decide which are needed to eliminate or reduce potential hazards to acceptable levels.
• Determine target levels and tolerances for control points - (eg. time).
• Establish monitoring systems for critical control points - (eg. work out who should act and when, where and what action should be taken).
• Establish a recording and documentation system.
• Review the HACCP system - annually and when changes are made to any process.