Safe Cooking

When food is thoroughly cooked, the heat kills food poisoning bacteria by cooking them too.  Therefore, in foods which are not thoroughly cooked, e.g. rare beef or a poorly cooked omelette, it is obvious that bacteria will survive the cooking process. What is less well known is that some food poisoning bacteria can even survive very high temperatures.

It is, therefore, essential that good quality food is used.  All raw meat, fish or any leftovers to be reused must be correctly stored in a refrigerator below 8°C (41°F) or hot above 63°C (145°F) to prevent growth of bacteria.

Hints For Thorough Cooking

• A safe way of cooking food is to achieve a high temperature then serve the food immediately.  Burgers, steaks and small pieces of food can be thoroughly cooked in this way by frying or grilling.
• Large Joints or poultry take a long time to cook through to the centre.  Small joints (2.5 kg, 5-6 lbs) are the recommended maximum size as they will cook and cool quickly.  For this reason, stuffing of poultry should be avoided.
• Bulk cooking e.g. stews can be difficult to cook thoroughly. It is important that such dishes are stirred to ensure even distribution of heat.  The core (centre) temperature of the food should be taken.
• Ice in the centre of a bird or joint will prevent proper cooking and let bacteria survive and grow. Ensure thorough thawing of frozen poultry and joints.
• Beans such as kidney beans and rice can also cause poisoning if not properly cooked.  Ensure these are brought to the boil and cooked in accordance with instructions on the packet.
• Plan cooking of food to finish as close as possible to the time of serving to prevent the growth of any surviving bacteria.
• Probe thermometers can be used to check that food has reached the right temperature.  Centre joint temperatures should be at least175°F.   NOTE Sterilise probe before and after use.

Cooling Of Food

It is safest to cook and serve food straight away or if not, it must be kept hot, above 63°C (145°F), so that bacteria will have no chance to multiply.
If food is to be served cold, or to be reheated later, it is essential that it is not allowed to remain in the 'danger zone' of 5°C (41°F) to 63°C (145°F) for longer than necessary. Safe cooling of food varies according to the style of catering and the equipment available.

Hints For Safe Cooling

• Plan menus and style of catering to suit the cooling facilities which you have available.
• Do not leave cooked food unrefrigerated for more than 1.5 hours.
• Do not put hot food in the refrigerator.  This increases the temperature in the refrigerator and causes condensation
• Smaller quantities of food cool fast.  Use small joints or poultry, and put sauces and casseroles in large flat pans to encourage rapid cooling before refrigeration.
• Advice on methods of cooling you may be using is given below:

Safest - Blast Chilling
A blast chiller is a refrigerator which blasts cold air across food to cool it from cooking temperature to below 3°C  (37°F).  FOOD poisoning bacteria will have no chance of growth.

Acceptable - Cold Stores
A large cold store operating at 1°C - 4°C (34°F - 39°F) should have plenty of cooling capacity to reduce food temperatures quickly enough to prevent significant growth of food poisoning bacteria.

Doubtful - Catering Refrigerators
Catering refrigerators operating at 1°C - 4°C (34°F - 39°F) may be able to cool smaller quantities of food satisfactorily if not too much is placed in them at any one time. They should not have been overloaded with other foods.

Unsuitable  - Domestic Refrigerators
Domestic refrigerators are only designed to keep food cold, and they cannot cool large quantities of food within an acceptable period of time.  Domestic refrigerators should not be used for any commercial catering purpose.

Reheating

Reheating of food and use of leftovers should be avoided as this can be potentially dangerous.  Careful menu planning should avoid the use of leftovers.  Unless it is thoroughly reheated, bacteria in food will have another chance to multiply and cause food poisoning.  Leftover meats are best served cold. Sauces and gravy should be freshly prepared.

In some catering systems such as cook-chill, where food is reheated strict management control and specialised equipment is required to ensure safety.

If food must be reheated for service it must reach at least 75°C throughout. A forced air circulation oven or infrared unit should be used. Food should never be reheated more than once.

Microwave ovens may reheat food unevenly and it is essential to check the temperature of food at various points, including the centre and around the edge.

Domestic microwaves are unsuitable for use in commercial kitchens