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    • Define TCS food and name two examples of TCS foods.
    • Describe the temperature “danger zone” and how exposure time can create an optimal environment for bacteria to grow.
    • Identify four instances when controlling time and temperature is critical in the food preparation process.
    • List three ways to properly thaw frozen foods.
    • Demonstrate the proper way to take temperatures of various types of food.




    TCS Food

    All food can potentially carry harmful bacteria, but some foods are especially conducive to promoting bacterial growth. Several factors affect the rate at which bacteria grow in food, but time and temperature are two of the most easily-controlled factors in a food service kitchen. Food that requires time and temperature control for safety is referred to as TCS food. TCS food has several attributes that make it ideal for bacterial growth, such as moisture, protein, and a neutral or slightly acidic pH.

    TCS food can be whole food, or it can be food that has already been prepared, like a casserole. TCS food can be from animal or plant sources. Foods that are considered TCS include:

    • Milk and other dairy products
    • Meat (beef, pork, lamb) or poultry (chicken, turkey)
    • Fish and shellfish
    • Eggs
    • Baked potatoes
    • Plant-based foods that have been heat-treated (cooked rice, beans, or vegetables)
    • Soy foods (tofu, textured soy protein/meat alternatives)
    • Sliced or cut fruits or vegetables (e.g. cantaloupe or melons, leafy greens, tomatoes, etc.)
    • Bean sprouts and sprout seeds
    • Untreated garlic-and-oil mixtures
    photos of the various tcs foods such as dairy, meat, untreated oils, fish and shellfish, cooked beans and rice, cut vegetables and fruits.

    Print out the mini-poster below illustrating TCS foods and hang it in your kitchen facility, if space permits, or store the information in a Resource Binder or similiar place within your facility.

    Factors that Affect Bacterial Growth

    There are six factors that affect bacterial growth on food. These are food, acidity, time, temperature, oxygen, and moisture. How acidic a food is, as measured by pH, can also influence how quickly bacteria can grow. Bacteria tend to grow in foods with a pH between 4.6 and 9.0. Low pH foods—those that are more acidic—include things like pickled foods, jams or jellies, honey, and fruits. High pH foods—those that do not have much acidity—include meats, milk, and vegetables. Most bacteria that cause foodborne illness grow well in conditions that do not have much oxygen, which is why it is important to control other factors that promote bacterial growth in food. Bacteria need moisture to grow, and the amount of moisture in a food is measured by water activity. The higher the moisture in a food, the better the conditions for bacterial growth. The water activity scale ranges from 0 to 1.0, with distilled water being 1.0. Most foods have a water activity of at least 0.95, meaning that bacteria have sufficient moisture to grow.

    A food handler cannot control a food’s acidity, oxygen, or moisture; these properties are inherent to the food itself. However, in food service, the remaining two factors, time and temperature, can be controlled. Time and temperature are closely related. Bacterial growth in ideal conditions happen rapidly: the amount of bacteria can double every 15 to 20 minutes. This is especially true when the temperature of food falls in the temperature danger zone. The temperature danger zone ranges from 41 F to 135 F (5 C to 74 C). The longer a food stays in this temperature range, the higher the risk for bacteria to grow rapidly in a TCS food. It is recommended to limit the length of time a TCS food is in the temperature danger zone to no more than four hours.

    Controlling Time & Temperature from Receiving through Preparation

    Receiving Food

    It is important to make sure you check the temperature of TCS food during the receiving process. This will help you gauge whether food was exposed to the temperature danger zone during transit. Document each food’s temperature on a designated temperature log. Refrigerated TCS foods should arrive at 41 F (5 C) or colder. Frozen TCS food should arrive at 0 F (-18 C) or colder. Hot TCS food should be received at 135 F (57 C) or higher; as with cold or frozen TCS food, be sure to document the temperature of hot TCS food upon receipt using a designated temperature log. Frozen TCS food with ice crystals or frozen liquid, fluids, or water stains should not be accepted. Additionally, any food that has passed its use-by or expiration date, has an off odor, abnormal color, or mold, or any meat, fish or poultry that is slimy, sticky, or dry should be rejected.

    Storing Food

    Maintaining proper temperature during storage of TCS food is very important. Temperatures should be checked and recorded regularly. Food storage time should be documented. This is accomplished through writing down the date a food was put into storage and when it should be used directly on the food itself. Labels are a good way to do this. Here are some safety tips for safely storing TCS food:

    • Refrigerated TCS food should be stored at 41 F (5 C) or colder so that the internal temperature of the food maintains this temperature.
    • Keep frozen food frozen; do not allow it to thaw.
    • Do not overcrowd freezers or refrigerators; this can cause the temperature inside the equipment to become warmer and expose the food to dangerous temperatures.
    • Minimize how often you have to open refrigerator and freezer doors.
    • Label TCS food when it goes into storage. The label should include the name of the food, the date it went into storage, and the date it should be used by. Ready-to-eat TCS food prepared on-site in your facility must be used within seven days if held at 41 F (5 C) or lower.
    • Be sure to rotate food during storage so that the food with the earliest use-by date is in front of foods with later dates. (As discussed in Lesson Four, this is called FIFO rotation, or first in, first out.)

    The proper temperatures for kitchen equipment are as follows:

    • Refrigerators: 40 F (4 C) or colder
    • Freezers: 0 F (-18 C) or colder
    • Dry storage: 50 F to 70 F (10 C to 21 C), with relative humidity of 50 to 60 percent

    Record the temperature of your facility’s walk-in refrigerators and freezers on an approved temperature log. Your program may use a specific form, or you can use the temperature log template below.

    Thawing Food

    There are four ways to properly thaw frozen food. Which method you use depends on the type of food you thaw. It is important to thaw food properly to minimize how much time the food is in the temperature danger zone to inhibit bacterial growth.

    Thawing Method

    1. In the refrigerator

      Thawing food in the refrigerator takes at least 24 hours, so this method requires planning ahead. Place the food on a tray in case any fluids leak from the package. Food should be placed on the bottom shelf of the refrigerator to thaw. The temperature inside the refrigerator should be 40 F (4 C) or colder.

      The refrigerator method is the safest method for thawing meat and poultry.

    2. In cold water

      This method is quicker than the refrigerator method and usually takes several hours, depending on the weight of the food. Place the frozen food item in a watertight plastic bag and completely submerge the bag under cold running water, 70 F (21 C) or colder. If thawing using this method, the food must not be above 41 F (5 C) for more than four hours. Once thawed, food should be immediately cooked.

    3. In the microwave

      Use the microwave method for immediate thawing and cooking. To thaw food using the microwave, remove all original packaging and place the food in a microwave-safe container. Follow the instructions in the microwave’s user manual for thawing foods (or defrosting foods) in the microwave. (This method is not ideal for large meat items like roasts or turkey.)

      Once thawed, the food should be cooked immediately.

    4. As part of the cooking process

      Food can be thawed as part of the cooking process, such as when you cook a frozen hamburger patty. Cooking frozen food directly does add to the total cooking time required for the internal temperature of the food to reach the required temperature for that food.

    Source: Academy of Nutrition and Dietetics, National Restaurant Association

    Preparing Food

    When preparing TCS food, make sure that the food is not exposed to the temperature danger zone for too long. The total amount of time that a TCS food can be in the danger zone is fewer than four hours. During preparation of TCS food, pay attention to how long the food is in the danger zone. Prepare TCS food in small batches, which helps prevent ingredients from being in the temperature danger zone for too long. Once the food is prepared, return it to the refrigerator as quickly as possible.

    Controlling Time & Temperature during Cooking, Holding, Cooling, and Reheating

    Cooking Food

    To reduce the risk of foodborne illness, TCS food should be cooked to an internal temperature specific to the type of food item it is. The table below lists the minimum internal temperature for various TCS food categories, as well as how long each food should be at that temperature.




    Rest Time

    Ground meat & mixed dishes

    Beef, pork, veal, lamb

    160 F for 15 seconds


    Chicken, turkey

    165 F for 15 seconds


    Fresh beef, veal, or lamb

    Steaks, chops, roasts

    145 F for 15 seconds

    3 minutes


    Whole or cut up chicken, turkey, duck, or goose

    165 F for 15 seconds


    Stuffing (cooked alone or inside a bird)

    165 F for 15 seconds


    Pork or ham

    Fresh pork or ham

    145 F for 15 seconds

    3 minutes

    Precooked ham

    140 F for 15 seconds


    Eggs & egg dishes


    Cook until yolks and whites are firm


    Egg dishes

    160 F for 15 seconds


    Leftovers & casseroles

    Any leftover dish being reheated

    165 F for 15 seconds



    165 F for 15 seconds



    Fin fish

    145 F for 15 seconds


    Shrimp, lobster, or crabs

    Cook until flesh is pearly and opaque


    Clams, oysters, or mussels

    Cook until shells open



    Cook until flesh is milky white or opaque and firm



    Holding Food

    Once a TCS food has been cooked, it must be held at the correct internal temperature for that food. Cold TCS food must maintain a temperature of 41 F (5 C) or colder, while hot TCS food must maintain a temperature of 135 F (57 C) or hotter. Using covers whenever possible helps to maintain the proper temperature of TCS food. Temperatures of held TCS food should be taken every two hours. Any prepared food that falls in the temperature danger zone (41 F - 135 F) for more than four hours should be thrown out.

    Cooling Food

    Guidelines for cooling TCS food are as follows: first, bring the food down from 135 F (57 C) to 70 F (21 C) within two hours. If the food does not reach 70 F within two hours, it will need to be reheated to 135 F (57 C) and then cooled again. Next, bring the temperature down from 70 F (21 C) to 41 F (5 C) within four hours. The total cooling time should not exceed six hours. The best ways to cool foods rapidly include using an ice bath, transferring the food to a shallow pan, and dividing dense foods, like lasagna or casserole, into smaller portions. Record the temperature of the food during the cooling process on a temperature log to ensure that it cools properly.

    Reheating Food

    When reheating food, the internal temperature of the food must reach 165 F (74 C) within two hours. Take the temperature to ensure the food has reached 165 F (74 C) for 15 seconds. Once this minimum temperature has been reached, the food should be held at 135 F (57 C) or warmer.


    What Does Temperature Control and Proper Cooling Look Like?

    Controlling how long TCS food is in the temperature danger zone is critical to minimizing the risk of foodborne illness. Make sure to properly and rapidly cool down hot TCS food to minimize foodborne illness. Watch the following video, which discusses the importance of temperature control in commercial food preparation.

    eFoodHandlers Basic Food Safety Chapter 3: Temperature Control video:


    Different foods need to reach certain temperatures during the cooking process. How do you take the temperature to ensure you are getting an accurate read on the thermometer? The answer depends on the type of food you cook. For meat and poultry, insert the thermometer into the food in the thickest part for at least 15 seconds. If the meat or poultry has a bone, make sure the thermometer does not touch the bone—the bone holds more heat than the surrounding muscle tissue and thus might not indicate that the edible part of the food has reached the correct temperature. For meats like hot dogs or hamburgers, you will need to stick the thermometer through the vertical end. For casseroles and mixed dishes, insert the thermometer into the center of the dish.

    The video below demonstrates the proper way to take temperatures of different foods during the cooking process. Watch the video, and discuss the process with your supervisor. Hang the Use That Thermometer mini-poster in your kitchen facility.

    eFoodHandlers Supplemental Video: How to Use a Thermometer:



    Over time, thermometers may lose their ability to accurately measure temperatures. Therefore, it is important to routinely calibrate thermometers used to take the temperatures of foods. Watch the video below that shows the steps to calibrate various types of thermometers used in food service. Then, calibrate the thermometers in your facility. Use the Using and Calibrating Themometers and the Thermometer Calibration Log for each thermometer in your facility and record your results. Make a plan to calibrate thermometers in your facility regularly, such as once a week.

    Calibrating Thermometers

    Watch this video to learn about different methods to calibrating thermometers.



    Taking the temperature of foods during all phases of food preparation is critical to ensuring that TCS food is kept safe from bacterial growth. Below are several types of temperature logs for recording temperatures of TCS foods through all phases of food procurement, preparation, service, and storage. Discuss each temperature log with your supervisor. Hang them in the appropriate areas in the kitchen and formulate a plan with your supervisor to regularly take temperatures and record them on the various logs.


    HACCP - Hazard Analysis Critical Control Pointsa preventative food safety control system that takes into account the hazards in food
    TCS foodany food that requires time and temperature control to minimize the growth of bacteria.
    Water activitythe ratio of vapor pressure in a food relative to that of distilled water. (Pure distilled water has a water activity of 1.0.) It gives an indication of how much moisture is available to bacteria in the food to grow. Most foods have a water activity of at least 0.95, meaning that conditions are ideal for growth of bacteria, yeast, or mold.
    Temperature “danger zone”the temperature range at which bacteria most readily grow; this range is 41 F to 135 F (5 C to 57 C).




    True or false? Keeping food at a proper temperature is out of a food handler’s control.


    Name the six factors that affect bacterial growth on food.


    Controlling time and temperature is not critical for TCS food during which food preparation process?

    References & Resources

    Academy of Nutrition and Dietetics (2015). Eat right. Thawing Frozen Foods. Retrieved from

    Boyer, R. R. (2012). Virginia Cooperative Extension, Publications and Education. How do you know if your food is safe to sell? Retrieved from

    Centers for Disease Control and Prevention. (2016). Estimates of Foodborne Illness in the United States. Retrieved from

    FoodSafety.Gov. (2018). Safe Minimum Cooking Temperatures. Retrieved from

    National Restaurant Association (2015). 8 tips to properly thaw and hold food.

    National Restaurant Association. (2017). Food Safety. Recognizing TCS foods. Retrieved from

    U.S. Food & Drug Administration. (2015). Inspection Technical Guides. Water Activity (aw) in Foods. Retrieved from