If foods heated up in connection with preparing them are not served directly after their preparation or stored hot, they must be chilled immediately after the preparation.
The cooling process must be carried out by cooling the food down to +6oC or below in four hours at the most. Faster cooling ensures better quality, safety and stability. If the cooling takes place too slowly or in too warm a temperature, the spores of bacteria that have survived in the food through the heating process may develop into growth forms, contaminating the food. Fast cooling and cold storage therefore also prevent food poisoning.
The following are among the factors that affect the speed of the cooling process:
- The size, shape and weight of the mass to be cooled
- Solidity and water content
- Thermal conductivity
- The material, heat storage capacity and thermal conductivity of the dish containing the food
- The cooling method.
If the regular operation of the food premises involves the cooling of food prepared by heating, the capacity and efficiency of the refrigeration equipment used for cooling must be sufficient in relation to the production. Cold storage equipment (refrigerated counters, cold cabinets, refrigerators, etc.) for chilled foods is generally not sufficient for cooling hot foods, especially if the equipment does not allow proper circulation of air.
The heat energy is transferred from hot food to the environment. The colder the environment, the more efficiently heat is transferred from the food to the environment. While the heat is transferred from the food to the environment and the food cools down, the environment warms up. For this reason, it is essential to keep the cooling element around the food (air, water, etc.) sufficiently cold during the entire cooling process. In practice, this means that if the cooling element is air, the air in the refrigeration cabinet is sufficiently cold (in some cases even below 0oC) and the ventilation is efficient so that the air surrounding the food is always cold and not warming up. If cold water is used in cooling, it must be ensured that the water surrounding the food is always sufficiently cold and not warming up. However, when cooling, the conditions must be adjusted to ensure that the food being cooled does not begin to freeze.
The following are examples of measures that can be taken to ensure sufficiently efficient and fast cooling:
- The thickness of the food layer to be cooled is reduced by cutting, slicing or dividing the food into several lower dishes.
- The thinner the food layer, the faster the cooling process. When being cooled, the thickness of the food layer should be less than 10 cm, preferably about 5 cm.
- If the food is in a tightly closed container, the container is immersed in cold water containing ice cubes or in running cold water.
Own-check activities must be accompanied by regular measurement of the initial and final temperatures of the food cooled, for example, four hours after the cooling process. At the same time, the layer thickness of the food being cooled is also monitored. This ensures that the foods cool down to the target temperature quickly enough. The temperatures are measured from the middle of the food, from the thickest area, where the cooling takes place the most slowly.
After the cooling process, the cooled food and other easily perishable foodstuffs are stored in a refrigeration cabinet or, for example, in a cooled storage space (see storage of foods, in finnish).
Remember these:
- Check the temperature of the foods requiring cold storage when you receive them. Do not accept products that are clearly too warm.
- Remember the cold chain in your own activities. Do not delay taking products requiring cold storage into the fridge or some other cold storage/refrigeration cabinet. Do not take foods to facilities warmer than cold stores to wait for handling unless this is an essential part of the preparation process. Do not overfill the refrigeration cabinets because they may then not be able to keep all products cold.
- If the food, the preparing process of which includes heating, is not served straight away, cool it as fast as possible. If you cool foods regularly, you must acquire equipment designed for the purpose, such as a refrigerator cabinet. You must also ensure that cooling takes place fast enough, in other words, from +60o to +6oC within four hours at the most. To ensure this, you must monitor the functioning of your refrigeration unit or method. Remember to transfer the foods you have cooled into the fridge or some other cold storage/refrigeration cabinet as soon as possible after the cooling process.
- Keep an eye on the functioning of the cooling equipment and the temperatures of cold food kept available for customers. Are the temperatures in the equipment cold enough? Are there differences in the temperature in different parts of the refrigeration cabinet? Make sure that the temperatures of foods requiring cold storage are below the danger zone (below +6oC) if legislation requires it. The temperature of easily perishable foods should not rise above +12oC even during serving.