Temperature control

Food that may contain food-poisoning bacteria and will support their growth are called potentially hazardous foods.

The temperature of these foods must be controlled to ensure bacteria do not reach levels in the food, or form toxins (poisons) in the food, that could cause food poisoning.

Examples of potentially hazardous foods are:

• raw and cooked meat
• smallgoods such as strasbourg, ham and chicken loaf
• dairy products and dairy-based desserts such as cheesecakes and custard tarts
• seafood
• processed fruits and vegetables
• cooked rice and pasta
• foods containing eggs

Temperature danger zone

Most types of bacteria that cause food poisoning grow in potentially hazardous foods at temperatures between 5ºC and 60ºC. This temperature range is called the temperature danger zone.

Some types of bacteria will grow at low temperatures, in refrigerators or cool rooms. In order to prevent bacteria growing to levels that could cause illness, potentially hazardous food stored at 5ºC should not be kept for more than 7 days.

Bacteria will not grow in frozen food. Freezing does not destroy bacteria, and they will grow rapidly when the food thaws. Manufacturers’ recommendations on food labels are a good guide to how foods should be stored.

Foods that are not potentially hazardous may become potentially hazardous if you alter the food in some way.

Custard powder, for example, is not potentially hazardous because it is too dry for bacteria to grow. But the custard becomes potentially hazardous when milk is added.

Most raw whole fruit and vegetables are not potentially hazardous because they do not allow any food-poisoning bacteria to grow. But, when they have been cut, bacteria may be able to grow on the cut surface, and so prepared fruit and vegetables should be stored chilled.

Using a thermometer

Temperature control is the use of temperature to protect the safety of food and minimise the growth of bacteria. This means keeping chilled food at 5 ºC or below, and hot food at 60ºC or above.

If you prepare or sell potentially hazardous food, you must have a thermometer to check the temperature of the food.

The thermometer must be a food grade thermometer, which is accurate to plus or minus 1ºC. The thermometer must have a probe so that the internal temperature of food can be measured.

The thermometer must be kept at the food business and must be cleaned and sanitised before every use. This is important to prevent contamination from one food to another.

Chilled potentially hazardous food

• Regularly monitor the temperature of your cool room and refrigerators to ensure they keep food between 0ºC and 5ºCs.
• Record these temperature checks, the date and time they are done, and the temperatures measured.
• Randomly check food items to ensure that chilled food is 5°C or below and that frozen food is frozen hard.
• Do not leave potentially hazardous food at room temperature. Refrigerate it.
• To maintain temperature, replace lids or close display unit doors when not being used.

Hot potentially hazardous food

• Regularly monitor your hot display units, hot holding ovens and bain maries to ensure they keep food at 60ºC or above.
• Record these temperature checks.
• Stir liquid foods to ensure an even temperature.
• Replace lids on serving dishes on buffets to maintain temperature.
• Heat the food to 60ºC or above before placing in a hot display unit.

Transporting food

When you receive potentially hazardous food, you must accept it only if it is 5ºC or below, or 60ºC or above.

• Measure and record the temperatures of these foods when they arrive.
• Measure and record the temperatures of these foods when they leave the premises, for example, before they are transported to another site.

Preparing and processing food

When preparing potentially hazardous foods bacteria may grow. Monitor the time food is at room temperature, and keep it as short as possible.

Bacteria may grow in foods during thawing.

• Only remove potentially hazardous food from the refrigerator when you need it.
• Serve the food or return it to the refrigerator immediately after preparation.
• Thaw frozen potentially hazardous food in a microwave, refrigerator or cool room.
• Thaw food completely before cooking.
• Do not refreeze thawed or partially thawed food.

Cooking potentially hazardous food

• Cook food such as meat and chicken to an internal temperature of 75°C or above.
• Use a probe thermometer to check internal temperatures.
• Whole pieces of meat such as roasting joints and steaks may be cooked rare.
• Chicken and minced meat dishes must be cooked right through to the centre.

Cooling the food

When cooling cooked potentially hazardous food, you must cool the food:

• from 60ºC to 21°C in no longer than 2 hours
• from 21ºC to 5°C in no longer than 4 hours

If cooked food is being cooled to serve later, you must cool it rapidly and then keep it at 5ºC or below.

• Allow hot food to cool slightly (about 20 minutes) and then refrigerate.
• Check that cooked foods are cooled in the required time. If foods are taking too long then:
  • divide large quantities of casseroles and other wet dishes into smaller quantities and place in shallow containers.
• slice roast meats and place the slices in shallow trays.

Reheating cooked and cooled potentially hazardous food

If reheating previously cooked and cooled food, you must reheat the food rapidly to 60ºC or above. Small portions heat faster.

Food must be reheated quickly because bacteria can grow while food is being reheated.

If the food is being reheated to serve or to display in a hot buffet, it must be rapidly heated to at least 60ºC. Keep the food at 60ºC or above until it is served.

Do not use bain-maries to reheat food. Reheat the food and then place in the hot bain-marie.

Reheat food once only.

Using time as a control

There are occasions when it is impractical to keep the food at 4ºC, or 60ºC or above. Some examples are buffets at weddings and lunches for meetings. The food will be safe for a short time, unless it has been contaminated during handling.

The maximum time that potentially hazardous food can be in this temperature danger zone of 5ºC to 60ºC is 4 hours. After 4 hours, any remaining food must be thrown away.

The 4 hours must include any time that the food was between 5ºC and 60ºC during:

• handling
• preparation and processing
• after processing
• transport
• in the case of buffets, the time setting up.

If you wish to display or hold potentially hazardous food between 5ºC and 60ºC and then refrigerate the food, you must not leave the food between 5ºC and 60ºC for longer than 2 hours.