What is temperature control in food

The temperature danger zone has its name for a reason. A single bacterium doubles every 20 minutes in the right conditions, meaning it can multiply trillions of times in just 24 hours without proper attention to food safety. The temperature danger zone is between 41℉ and 135℉—a temperature range in which pathogens grow well. Harmful microorganisms can grow to levels high enough to cause illness within four hours.

Foods That Need Time and Temperature Control

Any type of food can host contaminants, but some foods are better than others for the growth of pathogens. Foods that need time and temperature control for safety—known as TCS foods—include milk and dairy products, eggs, meat (beef, pork, and lamb), poultry, fish, shellfish and crustaceans, baked potatoes, tofu or other soy protein, sprouts and sprout seeds, sliced melons, cut tomatoes, cut leafy greens, untreated garlic-and-oil mixtures, and cooked rice, beans, and vegetables.

How to Thaw TCS Foods

• TCS food can be thawed one of four ways:
• Refrigeration — thaw at a temperature of 41℉ or lower.
• Running Water — submerge food under running water at 70℉ or lower.
• Microwaving — only to be used if food will be cooked immediately after thawing.
• Cooking — include thawing in the cooking process.

TCS Holding Temperatures

• Cold foods must be maintained at 41℉ or less. 
• Hot food must be maintained at 135℉ or above.
• Be sure to check the temperature at least every four hours.
• Checking the temperature every two hours would be ideal to leave time for corrective action.
• Throw out food that is not 41ºF or lower, or 135ºF or higher.

Cooling Foods

Food must pass through the temperature danger zone quickly to reduce the growth of pathogens. First the food must be cooled from 135℉ to 70℉ within two hours, then cooled to 41℉ or lower in the next four hours. If the food has not reached 70℉ within two hours, it must be thrown out or reheated and then cooled again. The total cooling time cannot be longer than six hours.

The most effective way to cool food is to reduce its size. This involves dividing large containers of food into smaller containers or shallow pans. 

Methods for cooling foods include:

• Ice-water bath
• Ice paddle
• Blast or tumble chiller
• Using cold water as an ingredient (soups, stews, etc.)

***Note: Coolers are designed to keep cold food cold, not to cool hot food quickly.

Reheating Foods

Food that will be served immediately can be reheated to any temperature as long as the food was cooked and cooled properly. Food reheated for hot-holding must reach an internal temperature of 165℉ within two hours. The food needs to stay at this temperature for at least 15 seconds before serving.

Share this:

Reading Time: 4 minutes

Temperature control in the kitchen forms part of the food safety pillars which is critical in ensuring the prevention of bacterial growth and overall quality of foods.

Temperature control ensures that 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. 

One of the best ways to kill bacteria is by heat. Rapid changes in temperature also prevent bacteria from surviving. So heating foods quickly kills bacteria.

Cold temperatures actually only 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.

However, when foods are left out at 20+ °C (68+ °F) food spoils a lot quicker. This is why we talk about the danger zone.

The Danger Zone is a temperature range in which bacteria grow and multiple at its fastest. This ranges from 20 – 45 °C (68 – 113 °F). Bacteria can, however, grow and survive between 5 – 65 °C (41 – 149 °F). But the most common food-related bacteria grow at their best in the danger zone.

This is because our internal body temperature is at 37 °C (98 °F) and food poisoning bacteria are related to us by the food we eat. 37 °C (98 ° F) is, therefore, the optimum performance zone for these bacteria. This is true for bacteria such as E.coli and Salmonella.

Therefore keeping foods outside this range prevents rapid growth of bacteria.

How to manage hot foods

All hot foods, but especially those on display at a buffet or servery must be kept above 65.0 °C (149 °F) 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.

Keeping records for both the hot and cold display of foods is an important factor in temperature control. Remember that if it is not being monitored then it’s not being managed. Temperatures should be recorded at least 1 hour into service in order to ensure that everything is in order.

When it comes to the reheating of food, they should be heated to a temperature of 70 °C (158 °F) 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 grow and survive.

How to manage 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 degrees C (41 °F). Foods such as sliced fruits and juices can be kept below 7 degrees C (45 °F). 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.

How to manage the refrigeration of foods

Much like the display of foods. All perishable foods need to be refrigerated. This is so that foods do not spoil sooner than the expiry date. Remember that cold temperatures only minimise bacterial growth, but in some cases, bacteria such as Listeria monocytogenes actually thrive at refrigerated ranges.

This is why all five of the food safety pillars are essential in a food safety management system.

Nevertheless, high-risk foods need to be kept below 5 degrees C (41 °F). Fruit and vegetables should be kept below 7 degrees C (45 °F) as is the case when displayed. Frozen foods need to be kept at -12 degrees C (10 °F).

However, colder temperatures up to -20 °C (-4 °F) will allow you to keep food for up to six months.

Ice-cream is particularly unique due to its consistency and must be kept below -18 °C (0 °F). This keeps ice-cream solid, preventing crystallization and therefore minimising layers in the ice-cream in which bacteria can survive.

Maintaining refrigeration units is vital to ensuring safety and quality and should also be monitored on a daily basis, to ensure correct temperatures are kept.

Keeping records will also allow you to detect ongoing maintenance concerns or whether the doors were left open for too long due to negligence.

How to keep temperature records

• List each fridge/freezer in the kitchen
• Record at least 4 hot and 4 cold foods if you display your foods
• Purchase a hand-held digital probe thermometer (you can review the different types here)
• Place a vial of water or stick of butter in each fridge/freezer
• Use the thermometer to record the core temperature
• Record these temperatures twice daily and/or at each buffet service for the foods.

Controlling the temperature of food is extremely important in ensuring that food is safe to eat, and you must ensure that food is always cooked, cooled, chilled or reheated properly to minimise the risk of harmful levels of bacteria in the food that you sell.

Meat products are typically regarded as high risk, but dried goods such as rice and pulses and vegetable and salads are also likely to contain bacteria that may grow if the food is subject to poor temperature control.  Perishable food should always be kept out of the danger zone of 8 - 63ºC to prevent the growth of harmful bacteria.

Cooking and reheating

In raw foods, such as meat, fruit and vegetables, high levels of bacteria may be present due to contamination with soil or due to the preparation process.  It is important that food is cooked thoroughly to a core temperature of at least 75ºC for at least two minutes to kill the bacteria.

One way to check whether the food has been cooked thoroughly would be to use a probe thermometer, but you must also take care that probe thermometers do not contaminate or taint the food being probed.  You can do this by cleaning and disinfecting them before use with ready to eat food.  Where antibacterial wipes are used to do this, they must be suitable for use with food.

It is also recommended that you keep a record of checks that you make. It is good practice to check and record at least two or three high-risk food temperatures per day.

Chilling

Chilling food does not kill bacteria, but it does stop them from growing to harmful levels.  Because of this, it is a legal requirement that perishable foods should be kept refrigerated at 8ºC or below. Frozen food should ideally be kept at a temperature at or below -18ºC.

It is good practice to check and record fridge and freezer temperatures at least once per day. If a fridge cannot keep food below 8ºC, it must be serviced or replaced.

Cooling

The legislation states that foods must be cooled as quickly as possible.  Methods such as reducing portion size, spreading food on an open tray or using ice can help to cool food quickly before it is refrigerated, and you should aim to cool foods to below 8ºC within 90 minutes.

Hot holding

If food is to be held hot, it must be cooked to at least 75ºC for two minutes and then held at a temperature at or above 63ºC. This is a legal requirement and it is good practice to check whether foods that are being held hot are at or above 63ºC on a regular basis.

More information

The Food Standards Agency website has lots of advice to help you.

Page 2