In the last module, you learned about the four food safety hazards. Now we look at how to keep them out of food.

Contamination is often caused by carelessness, so good everyday habits make a real difference. In this module, you will learn how to stop harmful bacteria from reaching food and multiplying, how to check deliveries and store food safely, and how to prevent allergenic, physical and chemical contamination.

This module covers:

• The four conditions bacteria need to grow, and the danger zone.
• Low-risk and high-risk foods.
• Controlling microbiological hazards.
• Checking food deliveries.
• Date marks, stock rotation, fridges and freezers.
• Controlling allergens, and responding to an allergic emergency.
• Controlling physical and chemical hazards.

Harmful bacteria need four conditions to multiply:

• Warmth.
• Time.
• Food.
• Moisture.

When all four are present, bacteria can quickly multiply to dangerous numbers. Taking away even one of these conditions slows or stops their growth. This is why food businesses control temperatures, limit the time food spends out of the fridge, and keep food covered and stored correctly.

Harmful bacteria grow between 5°C and 63°C. This range is called the temperature danger zone. They grow fastest at around body temperature, 37°C.

Below 5°C, bacteria grow very slowly, and in a freezer they stop growing. But cold does not kill them. As soon as the food warms up into the danger zone, they start to multiply again.

So chilled food must be kept below 5°C, and hot food must be kept above 63°C.

Thorough cooking kills most harmful bacteria. Food must reach a high enough temperature, for long enough, right through to the centre.

The Food Safety Authority of Ireland, or FSAI, advises cooking food to a core temperature of 75°C. Other combinations, such as 70°C for 2 minutes, give the same result.

Once cooked, hot food that is kept for serving must stay above 63°C, out of the danger zone.

In warm, moist conditions, bacteria can divide in two about every 10 minutes. This is called binary fission.

So 200 bacteria become 400 after 10 minutes, 800 after 20 minutes, and 1,600 after 30 minutes. A few bacteria can become a dangerous number in a short time.

This is why food, especially high-risk, ready-to-eat food, must spend as little time as possible in the danger zone.

Bacteria cannot easily multiply in food that is dry, or high in sugar, salt or acid, such as vinegar or lemon juice. These are low-risk foods. Examples include:

• Breakfast cereals.
• Dried pasta and dried pulses.
• Canned food, while unopened.
• Jam.
• Crisps.

They do not need a fridge, but must be kept cool and dry. If water is added, they can become high-risk. Cooked rice, for example, must be refrigerated.

Whether a food is low-risk or high-risk is not fixed forever. It depends on its condition, and that can change during handling. Dry foods, and foods high in sugar, salt or acid, such as those preserved in vinegar or lemon juice, are low-risk because bacteria cannot easily multiply in them. But once moisture is added, the picture changes. Dried rice is low-risk in its packet. Once it is cooked, it becomes high-risk and must be refrigerated.

Rice also shows why spores matter: Bacillus cereus can survive boiling inside a spore, and when cooked rice is left warm, the bacteria come out and multiply. Canned food is low-risk while the can is unopened, but once opened its contents must be treated like fresh food, moved into a covered, food-grade container and refrigerated. Leaving food in an open can risks metal residue entering the food. And opened packets of dry goods should be kept in sealed containers, in cool, dry conditions, so they stay free from moisture and pests.

High-risk foods are usually moist, rich in protein, and ready to eat without further cooking. Examples include:

• Cooked meat and poultry, and meat products such as pâté, pies, stews and gravy.
• Dishes made with raw egg, such as mayonnaise.
• Milk, cream, soft cheese, custard and other dairy products.
• Shellfish and seafood, such as prawns, oysters and crab.
• Cooked rice.
• Prepared salads containing meat, egg, rice or mayonnaise.

Keep them refrigerated, protect them from contamination, and never use them after their use-by date.

These practices help to control harmful bacteria:

• Keep raw and ready-to-eat foods apart, during delivery, storage, preparation and service.
• Store raw meat on the bottom shelf of the fridge, so it cannot drip onto other food.
• Use separate, colour-coded equipment, such as chopping boards and utensils, for raw and high-risk foods.
• Use separate serving utensils for each food at a counter, including foods that contain allergens.
• Rotate stock, and remove any food past its use-by date.
• Throw away unfit or contaminated food safely.

When a delivery arrives, check the date marks, the temperature of chilled and frozen food, the packaging for damage or signs of pests, the cleanliness of the vehicle and driver, and the quality, quantity and description of the food.

If anything is not right, do not accept it. Tell your supervisor, and follow your workplace procedure. When you do accept a delivery, record it, so that the food can be traced. Then put chilled and frozen food away first, as quickly as possible.

Checking deliveries is one of the first lines of defence against food safety hazards, and it protects the confidence customers have in the food they buy. Know exactly what makes a delivery unacceptable. Look at the quality of the food itself: how fresh it looks, its colour and its smell. Compare the product with its description, so you know you have received what was ordered. Check the date marks, and the temperature of any chilled or frozen food.

Examine the packaging for damage, and for signs of infestation such as gnaw marks, droppings or insects. Look at the condition of the delivery vehicle and of the driver too, because a dirty van or a driver handling open food with dirty hands can contaminate everything on board. If the food is sub-standard in quality, hygiene or temperature control, the delivery should not be accepted. Tell your supervisor. When you do accept a delivery, keep a record, so the food can be traced later if there is ever a problem.

• A use-by date is about safety. It is illegal to sell or serve food after its use-by date, even if it looks and smells fine.
• A best-before date is about quality. The food may still be safe after it, but it may not be at its best.

Rotate stock using first in, first out: place new deliveries behind older stock, so the older stock is used first. Check dates regularly, and remove any food that has passed its use-by date.

Correct storage temperatures stop harmful bacteria from multiplying:

• Fridges should run between 1°C and 4°C, so that food stays below 5°C.
• Freezers should run at -18°C or colder, usually between -18°C and -22°C.

Fridge and freezer temperatures should be checked and recorded regularly, usually at least once a day. If a unit is running too warm, report it to your supervisor immediately.

• Keep doors closed as much as possible, as cold air escapes quickly.
• Never tie back the plastic strip curtains on cold rooms.
• Do not overload them. Leave space between items so cold air can circulate.
• Never block the cooling unit with food.
• Never put hot food in a fridge. Let it cool first, as quickly as possible.
• Keep them clean and free of spills and debris.
• Report any fault straight away.

• Store raw meat and fish on the bottom shelf of the fridge, below ready-to-eat food, so they cannot drip onto it.
• Keep raw and ready-to-eat foods apart at all times.
• Keep allergenic foods separate, in sealed and labelled containers.
• Cover and label food, and keep it off the floor on clean shelving.
• Keep dry goods cool and dry, in sealed containers once opened.
• Store chemicals well away from food.

Even the tiniest trace of an allergen can cause a reaction, so always follow your workplace instructions. To control allergens:

• Keep allergenic foods packed and stored separately from other foods, in their own sealed containers.
• Keep them apart at every stage, from delivery to service.
• Use separate equipment and utensils for allergenic foods.
• Check whether any substitute product contains different allergens.
• Make sure products containing allergens are clearly labelled.

If a customer asks whether a food contains an allergen, find out. Never guess. A wrong answer could put their life at risk.

If someone has a severe allergic reaction:

• Call the emergency services immediately, and say it is anaphylaxis.
• Help them to use their adrenaline auto-injector, if they have one.
• Do not make them stand or walk. Let them lie down with their legs raised, or sit up if they are struggling to breathe.
• Stay with them, and keep them calm until help arrives.

Physical hazards are controlled by good maintenance, good housekeeping, and following your training. You should:

• Follow the dress rules: no jewellery or false nails, hair tied back, and protective clothing worn.
• Report worn, damaged or faulty equipment.
• Make sure you know how to use equipment correctly.
• Remove waste and packaging materials promptly.
• Sweep up broken glass safely, and report damage to the building.
• Report any sign of pests.

To prevent chemical contamination:

• Keep food and chemical deliveries separate.
• Store chemicals away from food, ideally in a locked, labelled cupboard or store.
• Always keep chemicals in their original, labelled containers.
• Never store food in old chemical containers.
• Cover or remove food before cleaning nearby.
• Use only food-grade packaging for food.
• Follow the manufacturer’s instructions for every chemical.
• Move the contents of opened cans into a covered food container before refrigerating.
• Report leaking equipment.