Understanding safe temperatures is an important part of buying and storage in AQA GCSE Food Preparation and Nutrition. Temperature control helps reduce the risk of harmful bacteria multiplying and causing food poisoning. You need to know the main temperatures for chilled storage, freezing, cooking and reheating, and be able to apply them to practical situations. For example, you may need to explain why raw chicken should be stored in a refrigerator, why a frozen meal must be thoroughly reheated, or why a cooked dish should not be left warm for too long. This guide covers the key revision knowledge for AQA specification section 3.4.2.1.
Why temperature control matters
Some microorganisms, including harmful bacteria, can multiply quickly when food is kept at unsuitable temperatures. The conditions that affect bacterial growth include temperature, time, moisture and the type of food. High-risk foods, such as cooked meat, poultry, fish, eggs and dairy products, need particularly careful handling because they can support bacterial growth.
Temperature control does not replace good hygiene. Hands, equipment and work surfaces should still be cleaned properly, and raw and ready-to-eat foods should be kept separate. However, controlling temperature is a key part of food safety from the moment food is bought until it is eaten.
Key safe temperatures to revise
The following figures are commonly used for GCSE food-safety revision. Always check the current advice from the Food Standards Agency and the latest AQA specification before an examination, because official guidance can change.
| Stage | Temperature or action | What it means in practice |
|---|---|---|
| Chilled storage | Usually below 5°C | Store perishable food in a working refrigerator and avoid leaving it at room temperature. |
| Frozen storage | Usually -18°C | Keep frozen food fully frozen and follow the storage instructions on the packaging. |
| Cooking | Core temperature of at least 75°C | The centre, or thickest part, of the food must reach the required temperature. This is different from the oven temperature. |
| Reheating | At least 70°C | Reheat food thoroughly so that it is steaming hot throughout, not just hot on the outside. |
A core temperature is the temperature at the centre of a food. The centre usually heats more slowly than the surface, which is why a thick piece of meat or a deep dish must be checked carefully. An oven set to 180°C does not mean that the food itself has reached 180°C.
Buying and storing chilled food
When buying food, check that chilled and frozen products are cold or frozen, that packaging is undamaged, and that dates and storage instructions are followed. Take chilled and frozen foods home promptly and put them away as soon as possible. In a practical situation, you could explain that delaying refrigeration allows food to spend longer in temperatures where bacteria may multiply.
In the refrigerator, store raw meat, poultry and fish separately from ready-to-eat foods. Raw foods should be kept in suitable covered containers or on a lower shelf so that juices cannot drip on to food that will not be cooked. Do not overload the refrigerator, because cold air needs to circulate. A refrigerator thermometer can help you check that the storage temperature is suitable.
Use-by dates relate to food safety and should be followed as instructed. Best-before dates mainly relate to quality. Pupils should check the current Food Standards Agency advice when revising date marking, as guidance can be updated.
Freezing and defrosting
Freezing slows microbial growth and helps food keep for longer, but it does not make food permanently safe or destroy every microorganism. Food should be frozen before its use-by date and wrapped or packed appropriately to protect its quality. Follow the manufacturer’s instructions for packaged frozen food.
Defrost food safely before cooking unless the packaging states that it can be cooked from frozen. Suitable methods depend on the food and the instructions. Defrosting in a refrigerator keeps the food colder than leaving it on a work surface. If a microwave is used, the food should normally be cooked immediately afterwards. Once food has defrosted, follow current official advice about whether it may be refrozen or must be cooked first.
Cooking food safely
Cooking can make food safer by destroying many harmful microorganisms. The food needs to be cooked thoroughly, particularly in the centre. For example, poultry should not be served if the thickest part is still raw or pink, and juices should run clear. A food thermometer can be used where appropriate, but visual checks and the manufacturer’s instructions may also be relevant.
For examination answers, link the temperature to the reason. A strong response might say that a chicken casserole needs to reach a safe core temperature because the centre must become hot enough to reduce harmful bacteria. Remember that colour alone is not always a reliable measure of safety, so do not confuse browning on the surface with thorough cooking.
Reheating food safely
Reheating is not the same as cooking from raw. Food that has already been cooked should have been cooled, stored and handled safely before reheating. Reheat it until it is thoroughly hot throughout, with a target of at least 70°C in the relevant GCSE guidance. Stir foods such as sauces or rice dishes where appropriate so that heat is distributed evenly, and follow the instructions for ready meals.
Only reheat food in a way that is suitable for that food and its storage instructions. Avoid repeatedly cooling and reheating the same dish. If food has been left out for too long or stored incorrectly, reheating may not make it safe, because some microorganisms can produce substances that are not removed simply by heating. Check current Food Standards Agency guidance for up-to-date advice.
Applying safe temperatures to practical situations
Temperature questions often test application rather than simple recall. Use this process:
- Identify the stage: buying, chilling, freezing, cooking, cooling or reheating.
- Choose the relevant temperature or storage action.
- Explain the food-safety reason, usually controlling the growth or survival of harmful microorganisms.
- Suggest a practical action, such as using the refrigerator, checking the centre of food, or following the packaging instructions.
For example, if a cooked pasta dish is to be eaten later, it should be cooled and stored safely rather than left warm for a long period. It should then be reheated thoroughly before serving. If frozen fish is being bought, it should remain frozen during transport and be returned to suitable frozen storage promptly.
Exam-ready retrieval checklist
- Can you state the usual chilled-storage figure of below 5°C?
- Can you state the usual frozen-storage figure of -18°C?
- Can you explain what a core temperature means?
- Can you recall the commonly taught cooking figure of at least 75°C?
- Can you recall the commonly taught reheating figure of at least 70°C?
- Can you explain why the centre of a thick dish needs checking?
- Can you distinguish a use-by date from a best-before date?
- Can you connect each temperature to reducing food-safety risk?
For the specification wording, consult the AQA GCSE Food Preparation and Nutrition specification. For current food-safety advice, check the Food Standards Agency and other relevant official sources before relying on a figure in practical work.
Frequently asked questions
Is the cooking temperature the same as the oven temperature?
No. The oven temperature is the setting around the food. The cooking temperature in this topic refers to the core temperature reached by the food, particularly at its thickest point.
Why is chilled food stored below 5°C?
Keeping perishable food properly chilled slows the multiplication of many harmful bacteria. It does not remove the need for hygienic handling or correct date and storage instructions.
Can reheating make badly stored food safe?
Not necessarily. Reheating may reduce some microorganisms, but it cannot be relied on to correct food that has been stored or handled unsafely. Follow current official food-safety guidance.