The Food Danger Zone; Thawing, Cooking, Reheating and Chilling
1624 days ago..

Last updated: 2019-06-25 14:53:34

With Christmas on its way everyone's thoughts turn to presents, good cheer and, of course, food. While people are busy deciding what comprises a perfect festive dinner they often fail to consider the food safety aspect before, during and after the meal. While restaurants must stick to strict guidelines and procedures unfortunately there are still occasional cases of illness that rear their ugly head around this time. Understanding the issues and learning how to combat dangers can ensure that your kitchen never falls foul to negligent practises.

The Danger Zone is the term for the temperature range between 4.4˚C/40˚F to 60˚C/140˚F.All foods must pass through the food Danger Zone whether they are to be stored, cooled, thawed or cooked. The amount of time that food stays within this zone should be minimised as much as possible. Any extended period of food items being left within this Danger Zone will result in a build-up of bacteria making the finished dishes potentially harmful to customers. These bacteria could lead to food poisoning for your guests, the overall outcome being ill customers, a poor reputation and loss of business. There are different methods utilised to safely bring items quickly and effectively through this Danger Zone and which all kitchen staff and chefs must be made aware of.


Frozen produce should always be stored below -17.7˚C/0˚F. At this temperature any bacteria is dormant however once the temperature is raised and the thawing process begins this bacteria will activate and could potentially become harmful. The following practises ensure food safety during the thawing process and reduce the length of time that food is kept in the Danger Zone.


If you are planning to thaw frozen items in your restaurant refrigerator it is vital that you keep the temperature at 4.4˚C/40˚F or cooler. Any thawing items must be placed away from chilled stock and on lower levels. This reduces any drips that occur throughout the thawing process, from potentially contaminating the rest of your produce. When thawing items in the refrigerator you should always take into account the time scale to fully thaw an item. Meats may take 24 hours, sometimes longer, to completely thaw.


Any packaging or wrapping that is plastic or metal/foil must be removed and the frozen food item placed into a suitable microwaveable container. On domestic and commercial microwaves there will be a ‘thaw’ or ‘defrost’ power setting which must be selected to safely prepare the food. Once the food has been completely thawed it must be cooked immediately to avoid the growth of any activated bacteria present on the food.

Cold water

Although this method is not as popular as refrigeration or microwaving it is still a preferred process for some. The food item should be sealed in a water tight bag and submerged in either a suitably sized container or a sink filled with cold water. The water should be changed approximately every 30 minutes whilst the thawing process takes place. Once the item has thawed thoroughly you should aim to proceed with the cooking procedure immediately to reduce the risk of any bacteria present reproducing.

Things to avoid when thawing

Items should never be thawed using warm or hot water. The temperature changes will be uneven and bacteria growth may be an unwanted result of this. Foods should never be left to sit at room temperature. Once the food items have thawed they will be firmly in the Danger Zone when left to stand and should not be used.


When cooking foods the temperature should always be checked regularly with food thermometers. Aim to take readings from the centre of the thickest part of the food to obtain an accurate temperature. All foods should be cooked to a temperature of at least 71˚C/160˚F. This guarantees that any bacteria that may have been present is killed before the dish is presented to the customer and consumed. Meats are notoriously the worst offenders for harbouring and cultivating harmful bacteria so special care should be taken when meat is involved.


If an item has been previously cooked and then chilled, reheating may be required. There are critical procedures and aspects that must be considered and assessed to eliminate the growth of any bacteria and ensure the safety of the food for your customers. The correct equipment must be used when reheating dishes. Acceptable equipment includes commercial grade microwave ovens, commercial grade conventional ovens or commercial ranges. All foods, no matter the item, should be temperature tested with an accurate thermometer to ensure that the food is safe for consumption. The recommended temperature should be at least 73˚C/165˚F. If you are reheating liquids you should always bring them to the boil before serving to ensure that bacteria have been killed. Simply warming the liquid through will not eradicate any active bacteria.


Sometimes commercial kitchens may purposely cook too much of certain ingredients to reduce the preparation time in the future. The safest way to chill any food for storage is to use a quality blast chiller. These pieces of equipment are specially designed to bring the temperature of cooked items down quickly through the Danger Zone to a safe temperature of below 4.4˚C/40˚F. Once the foods have been safely chilled, strict storage guidelines should be followed. Each item should be individually placed in airtight storage containers, labelled appropriately with the date of storage and a use by date and placed in a storage area that is maintained at an appropriate temperature.

Any food items that have been thawed, cooked, reheated or chilled should have their temperature monitored closely. If any ingredients stay at a temperature within the Danger Zone for longer than a two hour period they must be thrown away and should under no circumstances ever be served to customers. Once items have spent more than two hours within the temperature range of the Danger Zone no amount of cooling or cooking will be able to kill the growth of any bacteria which may be present.

Food safety is critical especially in businesses who supply the public with food. All members of kitchen staff should be fully trained as to the safety of food and the processes that should always be adhered to. By understanding the basics of food safety and following procedures accurately you can guarantee that the food which you serve is not only tasty and of a high quality but is also safe for your diners and able to maintain your restaurants good reputation.

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