Temperature control of food in the kitchen can simply be defined as keeping foods that are meant to be served hot are kept at the required temperature and foods meant to be served cold are not left out at dangerous temperatures, that allow bacteria to grow quickly. One of the most effective ways to kill bacteria is by using heat. Rapid changes in temperature also prevent bacteria from surviving. So heating foods quickly is able to kill bacteria.
Cold temperatures are only able to slow or minimise the growth of bacteria. Think about the foods in your fridge. When foods are kept in the fridge for longer than three days, foods start to food off. This is caused by food spoilage bacteria and takes a few days to happen in the fridge due to the minimum growth rate. Safe temperatures are 5°C or colder, or 60°C or warmer. Potentially hazardous food needs to be kept at these temperatures to prevent food-poisoning bacteria, which may be present in the food, from growing to levels where the bacteria can make you sick.
What foods are considered high-risk and need good temperature control?
- Raw meats, cooked meats and food containing meat, such as casseroles, curries, lasagne.
- Processed fruits and vegetables, such as prepared salads and ready-to-eat fruit packs.
- Cooked rice and pasta.
- Processed foods containing eggs.
- Dairy products and foods containing dairy products, such as milk, cream, custard and dairy-based desserts.
- Seafood (excluding live seafood) and food containing seafood, such as seafood salad.
- Foods that contain any of the above foods, such as sandwiches.
When foods are left out at temperatures between 20 – 45°C food spoils a lot quicker. This is why we talk about the critical danger zone.
The Critical Danger Zone is a temperature range in which bacteria grow and multiple at its fastest. This ranges from 20 – 45 °C. Bacteria can, however, grow and survive between 0 – 60 °C. Yet, the most common food-related bacteria grow at their best in the critical danger zone. Our internal body temperature is at 37 °C and many food poisoning bacteria are able to grow at their best at this temperature.
How to manage temperature control of hot foods
All hot foods, but especially those on display at a buffet or servery must be kept above 60.0 °C at all times.
In order to achieve this, hot foods must be kept in a pre-heated hot display that is above this temperature. If you place hot foods in a cool display it will take too long to get back up to the required temperature allowing bacteria to survive. The same is true for placing cooled foods into a hot display. Remember we need high and quick temperatures to kill bacteria.
When it comes to the reheating of food, they should be heated to a temperature of 70 °C for at least 10 minutes in order to ensure all bacteria has been killed. Warmers and Bain maries cannot be used to reheat foods because they do not rapidly increase the temperature, allowing time for bacteria to survive and cause illness.
How to manage temperature control of cold foods
In the case of high-risk cold foods such as prepared salads, deli meats and dairy, these foods must be displayed below 5° C. Foods such as sliced fruits and juices can be kept below 7 °C. This requires that a cold display be used to keep food cold and out of the danger zone.
This also means that these foods should be pre-chilled in a fridge or freezer for at least 30 minutes, and the cold display should be operating below the required temperatures before foods are placed out on display. Cold displays must be either refrigerated or kept on ice. We would recommend both in warmer climates. Crushed ice works particularly well as a display that is both appealing and functional.
Why use a thermometer?
A hand-held digital, probe thermometer is one of the most important pieces of equipment you can own in the kitchen. It is essential in ensuring that food is kept at safe temperatures. If your facility prepares, handles or sells any potentially hazardous food, it must have a thermometer which is accurate. This means that when the thermometer shows a temperature of 5°C, the actual temperature will be between 4°C and 6°C. The thermometer must be available for use when foods are being prepared, so you may need more than one if foods are prepared in different places.
How to clean and sanitise your thermometer
- The probe should be cleaned with a cloth using a food-grade detergent.
- The probe should then be sanitised, ideally using the fast-drying hand sanitiser, by spraying two doses of a QAC-sanitiser onto a clean piece of paper towel and then liberally applying the sanitiser to the whole length of the probe.
- The sanitiser should be allowed to dry.
Checking temperatures of food
- Once sanitised, the probe can then be inserted into the food until the tip of the probe is approximately in the centre (or core) of the food item.
- Tip: The core temperature is the most important temperature to take so do not let the probe tip be positioned too close to any surface of the food items being monitored.
- The probe should be held in this position until the temperature reading stabilises, that is until the numbers on the reading face stop changing.
- Once stabilised, the reading can then be deemed the true internal core temperature of the food item and the temperature should be recorded, with all decimal values, on the respective hot or cold food temperature checklist.
- For all individual food items being checked, points 2) to 5) above should be followed to ensure temperatures are taken hygienically and accurately.
ADRIAN CARTER
Hygiene Survey Manager
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