Module 3: Food contamination ‣ Skills Enhanced

NSW Food Authority | Food Handler Basics

In this topic you will learn about one of the most important aspects of food safety, food contamination. If you don’t understand how food contamination occurs or how to avoid it, you will not be able to work safely with food.

We will demonstrate:

Ways food can be contaminated
Symptoms of food poisoning
The role of bacterial contamination in food poisoning
Food spoilage
The temperature danger zone
High-risk and low-risk foods
Do’s and don’ts of cross contamination

Food contamination occurs when something is found in food that shouldn’t be there. Contaminated food can be unsafe for consumption.

Causes of food contamination

Biological hazards (microorganisms)
- Including bacteria, fungi, yeasts, mould and viruses.
Chemical hazards
- Including cleaning chemicals or foods with naturally occurring toxins, such as green potatoes.
Physical hazards
- Including dangerous physical objects such as plastic.

Beware! Selling contaminated food could lead to customer illness or injury, legal action taken by the local council and the customer, bad publicity including the closure of the premises or loss of your job.

You must follow the correct food handling techniques to ensure that food is not contaminated.

Food poisoning is most often caused by bacteria that have been able to multiply or form a toxin in the food.

Bacteria and other microorganisms can be found in soil, on animals, on people and on the things people touch and use.
One of the greatest threats to food safety is the fact that bacteria can multiply from just a few cells to millions in a very short period of time.

Some of the factors that affect the growth of bacteria include:

The temperature of food
The moisture content of food
The time they have to grow in food, particularly food kept in the danger zone of 5 °C to 60 °C.
Exposure to air.

Bacteria will not grow quickly if these factors are controlled.

Anyone who eats contaminated food can get food poisoning; however, vulnerable people are at higher risk of developing severe symptoms from unsafe food.

Food poisoning symptoms can appear within an hour or two, but may take up to 36 hours to appear.

Food Poisoning Bacteria

Food poisoning bacteria don’t affect the smell, taste or appearance of food.

Food poisoning is caused by contaminated food that has been poorly handled, stored or not cooked properly
You cannot tell just by looking at a food whether it has been affected by food poisoning bacteria
You could easily transport, prepare or sell food without knowing that it could cause food poisoning.

It is important to take steps to prevent food from being contaminated in the first place.

Food spoilage

There is a difference between food that is spoiled and food that can cause food poisoning.

Food spoilage is obvious, for example sour milk, mouldy bread or soft slimy fruit and vegetables. As spoiled food is unfit to eat it should be thrown out.

Food spoilage can be prevented by:

Rotating food using the first-in first-out rule to ensure that the first item purchased is the first consumed
Storing food correctly, for example storing meat in the refrigerator or freezer
Refrigerating, freezing, canning or vacuum packing food.

A major cause of food contamination is bacteria, which can multiply quite quickly given the right conditions.

Certain types of food allow quick growth of bacteria because they are generally moist and high in nutrients. These are called high-risk foods.

Foods that are less able to support bacterial growth are called low-risk foods. Low-risk foods do not need to go in the fridge and are typically dry foods.

High-risk foods in which bacteria grow quickly include:

Dairy products (such as custard and cream)
Meat
Poultry
Seafood
Cooked rice
Cooked pasta
Sliced delicatessen meats
Prepared salads, such as coleslaw, pasta salads and rice salads
Prepared fruit salads
Foods containing eggs (cooked or raw)
Ready-to-eat foods containing any of the above foods, for example sandwiches and sushi.

Low-risk foods in which bacteria do not grow quickly include:

Cereal
Flour
Confectionery
Sugar
Dry biscuits
Spices
Uncooked grains.

To handle eggs safely:

Wash your hands after handling eggs
Do not use dirty or cracked eggs; these eggs should be thrown away
Do not wash eggs as it makes it easier for bacteria to penetrate the shell
Refrigerate the egg product immediately after preparation as refrigeration will slow the growth of bacteria
Keep egg-based foods refrigerated until just before they are to be consumed
Foods with egg sauces must be prepared just before service and held only for the service period
Prepare only enough product to be used on the same day

Temperature danger Zone

Bacteria can grow on food that isn’t kept at the correct temperature.

Keep hot food HOT at 60 °C or hotter.
Keep cold food COLD at or below 5 °C.
Keep frozen food FROZEN at or below -15 °C.

The ideal temperatures for bacteria to multiply is between 5 °C and 60 °C.

This is called the ‘temperature danger zone’. Food should be kept between these temperatures for as little time as possible.

Bacteria multiply quickly especially in high risk food.

Cross Contamination

Cross-contamination occurs when harmful bacteria or allergens spread to food from other food, surfaces, hands or equipment. Food poisoning can occur when bacteria in raw food (such as meat juice) comes in contact with cooked or ready-to-eat food and the bacteria then have the chance to grow.

It is your responsibility as a food handler to prevent cross-contamination.

Module 3: Food contamination

Food Handler Basics Training