There are many factors that allow pathogens like bacteria to survive and multiply.
However, there are only two factors that you can control — time and temperature.
Some foods require time and temperature controls to keep them safe so we call them time and temperature control for safety (TCS) foods.
This article explains what TCS foods are, provides examples of them, and explains how to control time and temperature to keep TCS foods safe throughout the flow of food.
What are TCS foods?
Some foods grow bacteria more easily and quickly than other foods because they are rich in protein, moisture, and other nutrients that bacteria love.
These foods are called time and temperature control for safety (TCS) foods because they require certain time and temperature controls to prevent bacteria from growing and multiplying.
They can also be called potentially hazardous foods (PHFs) because they become hazardous if time and temperature are not controlled.
If you don’t handle TCS foods properly, you can encourage the growth and spread of pathogens like bacteria that cause foodborne illnesses.
Examples of TCS foods include (1):
- milk and milk products like cheese, sour cream, whipped butter, and ice cream
- meats, poultry, and seafood
- plant-based foods that are heat-treated, such as cooked onions, rice, baked potatoes, and soy protein products like tofu
- cut melons, tomatoes, carrots, and leafy greens
- raw seed sprouts
- garlic-in-oil mixtures
- ready-to-eat (RTE) foods, such as fruits, bakery items, cooked pizza, and deli meats
In contrast, foods can be non-TCS if they are processed or packaged in certain ways to slow or stop the growth and multiplication of bacteria.
Non-TCS food examples include:
- air-cooled hard-boiled eggs and pasteurized eggs with shells
- shelf-stable foods like flour, uncooked rice or pasta, and snack foods
- foods containing preservatives or packaged with reduced oxygen
- unprepared or uncut fruits and vegetables like carrots
- herbs and seasonings like salt and pepper
Ice, while it can become contaminated, is not a TCS food.
Unlike TCS foods, these foods are not PHFs and therefore don’t require time-temperature controls to keep them safe.
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TCS foods require time and temperature controls to keep them safe. Examples of TCS foods include milk and milk products, meats, poultry, seafood, RTE foods, and certain cut vegetables.
Temperature Danger Zone
Time and temperature are closely related but they must be both controlled and monitored closely when working with TCS foods.
Foods can be time-temperature abused if they are cooked, reheated, or held at the wrong temperature.
TCS food is considered time-temperature abused any time it remains between 41ºF and 135ºF (5ºC and 57ºC). This range is called the temperature danger zone since bacteria multiply rapidly in this temperature range.
Outside of the temperature danger zone, however, the growth of bacteria growth decreases significantly.
Thus, the best way to keep TCS foods safe is to keep them out of the temperature danger zone as much as possible.
However, TCS food can be kept with no temperature controls — such as at room temperature — for a maximum of four hours, at which time the food must be cooked and served, served if an RTE food, or discarded.
Food that was held above 41ºF (5ºC) can remain in the temperature zone for up to six hours if it doesn’t exceed 70ºF (21ºC).
Bacteria multiply quickly between 41ºF and 135ºF (5ºC and 57ºC). This temperature range is known as the temperature danger zone.
TCS throughout the flow of food
Time and temperature must be controlled throughout the flow of food, from receiving up to the point of service.
As you can imagine, there are several ways for food to become unsafe throughout each phase.
Here’s what you need to know about controlling time and temperature for receiving, thawing, cooking, cooling, and reheating potentially hazardous foods.
When receiving food, check its temperature and quality. Poor quality is a sign that the food has been time-temperature abused.
Only accept TCS food above 135ºF (57ºC) if it’s delivered as a hot food for holding, and 41ºF (5ºC) if it’s a cold food. In other words, only accept food if it’s outside of the temperature danger zone.
The exceptions are live shellfish, like oysters, clams, and scallops, milk, and eggs, which can be received at 45ºF (7ºC) but then must be cooled to at least 41ºF (5ºC) within four hours.
Frozen foods must be frozen solid when you receive them. If you see fluids, water stains, or ice crystals, the foods have been thawed and then refrozen and you should reject these items.
You should also reject food items if any of the following are present:
- mold or abnormal color
- moist when it is supposed to dry
- signs of pest contamination (bite marks or droppings)
- slimy or sticky, in the case of meats
- has an abnormal or unpleasant odor
- is not in its original packaging
- packaged with holes, tears, or punctures
- signs of tampering
- missing use-by or expiration dates
- items past their use-by or expiration dates
- cans that are dented, swollen, rusty, or have holes are leaking
Freezing stalls bacteria growth but it usually isn’t enough to completely destroy bacteria.
Consequently, improper thawing techniques provide an opportunity for bacteria to grow to harmful numbers.
Improperly cooling foods like poultry can also allow bacteria to survive the cooking process and make people sick.
- Thaw in a cooler at 41ºF (5ºC). This takes planning as large items like a roast can take several days to thaw.
- Thaw under running water at 70ºF (21ºC) or lower. Use a clean, sanitized sink, and never use warmer water as doing so can quickly bring parts of the food to the temperature zone.
- Thaw in a microwave at 50% power. Only use a microwave if you plan to cook it — but not in the microwave — immediately after thawing.
These methods are different from slacking, which involves raising the temperature of frozen food before cooking to save time and allow more even heat transfer.
With slacking, the food remains frozen — just less frozen.
In some cases, raising the temperature isn’t necessary.
Hamburger patties, for example, can go directly from the freezer to the grill and some types of frozen chicken can go directly into a deep fryer.
In these examples, the food passes through the temperature zone quickly, reducing the risk of pathogen growth.
It is not safe to thaw TCS foods at room temperature.
Cooking food not only makes food taste good, but it makes food safe.
While you might believe that you can rely on changes in color to indicate doneness, color is not a reliable indicator of whether a food has reached a safe internal temperature.
TCS food needs to reach a certain temperature — called the minimum internal temperature — and stay there for a specific amount of time to kill off pathogens or reduce them to safe levels.
Cooking, however, can’t destroy toxins or spores that may be present. This is why it’s important to handle food safely throughout its flow before it’s cooked.
Different foods have different minimum internal temperature requirements.
As a general rule, the more handling or processing a food receives, the higher its minimum internal temperature requirement.
Here are the foods and their minimum internal temperatures that you must know (1):
- 135ºF (57ºC): Plant foods that are cooked for hot-holding like rice or pasta.
- 145ºF (63ºC) for 15 seconds: Eggs served immediately and intact meats and seafood.
- 145ºF (63ºC) for 4 minutes: Roasts.
- 155ºF (68ºC) for 17 seconds: Cooked, ground, tenderized, or flavor-injected meats and hot-held eggs.
- 165ºF (74ºC) < 1 second (instantaneous): All poultry, stuffed meats, and stuffed pasta.
If you cook meats, poultry, or seafood in the microwave, follow these steps:
- cover the food using a lid to retain moisture and avoid splatter
- rotate or stir the food halfway through for even heating
- temp the food in at least two places to ensure all parts reach at least 165ºF (74ºC)
- let the covered food sit for at least 2 minutes after microwave
Cooking TCS foods to their proper internal temperatures is critical, but they must also be held at certain temperatures to keep them safe.
Food that is hot- or cold-held for service is at risk for time-temperature abuse.
Hold hot food at 135ºF (57ºC) or higher, and hold cold food at 41ºF (5ºC) or lower.
Regularly check the temperature of the food that is being hot- or cold-held to ensure the food is not in the temperature danger zone.
Many steam tables include a thermometer gauge. However, this gauge measures the temperature of the steam table, not the internal temperature of the food.
Therefore, always use a calibrated food thermometer to temp the food and do so at least every four hours. If any food is in the temperature danger zone, throw it out.
While not required, temping the food more often, such as every two hours, allows you to take corrective actions if you find that food is in the temperature zone.
For example, if you find that after two hours on the steam table, the roast beef is at 110ºF (43ºC), you can reheat it to 165ºF (74ºC) and return it to the steam table.
Never use the steam table or other hot-holding device for reheating food. Just as a fridge isn’t designed to cool food but keep food cool, a steam table is designed to keep food hot, not cook it.
Improper cooling and reheating can encourage bacteria growth or prevent bacteria from being destroyed.
This is because food passes through the temperature danger zone during cooling or reheating.
TCS foods hot-held for service at 135ºF (57ºC) must be cooled to 41ºF (5ºC) within six hours total.
This happens in a two-stage process.
In the first stage, cool food from 135ºF (57ºC) to 70ºF (21ºC) within two hours. Then, cool from 70ºF (21ºC) to 41ºF (5ºC) within four hours.
Food must be cooled to 70ºF (57ºC) quicker since bacteria grow at a rapid rate between 70ºF (21ºC) and 135ºF (57ºC).
When you’re working with large amounts of TCS food, it’s difficult to cool food fast enough.
Use shallow pans for dense or liquid items like casseroles, mashed potatoes, and soups, and cut thick items like roasts into smaller pieces to speed up the cooling process.
Using shallow pans and cutting up thicker items allows heat to dissipate or escape at a much faster rate.
Stainless steel transfers heat away from food faster than plastic and may be a better choice for cooling.
Here are acceptable methods for cooling TCS foods (1):
- Set up an ice-water bath. After dividing the food into smaller, stainless-steel containers, place them in a prep sink or large pot that is filled with ice water.
- Stir the food. Use an ice paddle — a hollow plastic paddle that can be filled with water and frozen — to stir the food frequently.
- Use cold water or ice as an ingredient. Make soups, stews, stocks, brines, and other liquid items with less water, and then add water or ice after it’s finished cooking to cool.
- Use a blast chiller. As the name suggests, a blast chiller blast food items with cold air to remove heat. Blast chillers are less frequently used due to their high price tag.
Never put large amounts of hot food in cold storage. This can raise the inside temperature of the cold storage unit, and consequently, the other items inside, to unsafe temperatures. Remember, cold storage is designed to keep your food cool, not chill them.
For (TCS) foods, mark the date or day by which the food needs to be served, sold, or tossed after opening if you plan to hold it for longer than 24 hours.
You can store TCS foods in the refrigerator for up to seven days, with the day you opened the container or package counting as day 1.
The process of reheating TCS food depends on how it will be used.
If you are reheating RTE food or leftovers that will be served immediately, you can serve it cold or reheat it to any temperature as long as it has been cooked and cooled correctly.
Pizza is one example. However, most food operations reheat food and hold it for serving.
If you reheat previously cooked TCS food for later service, you must heat it to an internal temperature of 165ºF (74ºC) for at least 15 seconds.
For commercially processed and packaged RTE foods like soup concentrates, reheat them to at least 135ºF (57ºC) for 15 seconds.
There are multiple opportunities for TCS foods to become unsafe so you must follow control time and temperature throughout the flow of food, from receiving up to the point of service.
The bottom line
TCS foods are those that require time and temperature controls to keep them safe.
They include animal products like meats, poultry, seafood, and milk products, but some plant-based foods are also TCS foods.
Cut melons, tomatoes, and leafy greens as well as plant-based foods that are heat-treated, such as cooked onions, rice, baked potatoes, and soy protein products like tofu are TCS foods.
There are multiple opportunities for TCS foods to become time-temperature abused through their flow. Knowing where these opportunities exist is key to preventing them and serving safe food.
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