Bulletin E3255
Cooking Safely with a Slow Cooker


October 24, 2022 - Laurie Mesing

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Cooking at a safe temperature

A slow cooker must reach the correct temperature to cook the food properly and to prevent the growth of foodborne pathogens. Pathogens are bacteria or viruses that cause illness. Although they usually exist in harmless quantities, they can multiply to dangerous levels if food is stored or cooked at inadequate temperatures. A safe slow cooker cooks slowly enough for unattended cooking, yet fast enough to keep food out of the bacterial danger zone in which pathogens grow quickly. The danger zone is 40 °F to 140 °F (USDA Food Safety and Inspection Service, 2011, October).

Making sure your slow cooker is cooking adequately

To test your slow cooker’s heating capacity:

  1. Fill the slow cooker with water about one-half to two-thirds full.
  2. Heat the slow cooker covered on low for eight hours.
  3. Using a food thermometer, quickly check the temperature of the water as the temperature will drop when you remove the lid.
  4. The temperature of the water should be 185 °F. If the temperature is below 185°F, your slow cooker does not heat food properly to avoid foodborne illness.

(Colorado State University, 2013, February).

If the slow cooker does not reach 185 °F, contact the manufacturer if it is still under warranty, which is generally 2 years. Any slow cooker older than 2 years that does not reach 185 °F may be unsafe to use. Contact your local government office to find out the best way to dispose of it.

Preparing food for the slow cooker

Follow these important food safety tips when preparing food to cook in a slow cooker:

  • Always wash hands before and during food preparation.
  • Always begin with a clean cooker, clean utensils and a clean work area.
  • Keep perishable foods refrigerated until preparation time. If you cut up meat and vegetables in advance, store them separately in the refrigerator to prevent cross contamination.
  • Always thaw meat or poultry before putting it into a slow cooker. Frozen meat or poultry may not thaw quickly enough to prevent the growth of pathogens. You may add frozen vegetables since they thaw more quickly.
  • When cooking vegetables in a slow cooker, add them in first. Fresh vegetables take more time to cook than meats and poultry. However, if using frozen vegetables, due to their processing time, they will cook faster than fresh vegetables.
  • Choose high-moisture foods, such as soups and stews, for slow cooking. The moisture generates steam, which facilitates cooking and helps raise the temperature above the danger zone quickly.
  • Check the amount of liquid suggested in a recipe. Don’t put too much or too little in your slow cooker. Fill it at least half-full but no more than two-thirds full.
  • If using a commercially frozen slow cooker meal, prepare according to manufacturer’s instructions.
  • Always check the slow cooker manufacturer’s instruction booklet to determine if suggested sizes of meats are appropriate for the slow cooker you are using.

(USDA Food Safety and Inspection Service, 2012, February; Colorado State University Extension. 2013, February).

Cooking with the slow cooker

Follow these important safety tips when cooking food in a slow cooker:

  • Make sure the slow cooker is sitting on a flat surface away from other objects.
  • Plug it firmly into the electric outlet
  • Keep the slow cooker covered as much as possible. Remove the lid only to stir the food or check for doneness. When the lid is removed, the temperature can dip 10 to 15 degrees.

Handling leftovers

Follow these important food safety tips for handling leftovers:

  • Do not reheat leftovers in the slow cooker. Reheat leftovers on a stove, or in a microwave or oven until the food reaches the proper internal temperature of 165 °F as measured with a food thermometer. (Find information on using a food thermometer on the Academy of Nutrition and Dietetics website at www.homefoodsafety.org.)
  • Place the hot food in a preheated slow cooker to keep it hot for serving at least 140 °F as measured with a food thermometer.
  • Store leftovers in shallow, covered containers, and refrigerate within two hours after cooking is finished.

(USDA Food Safety and Inspection Service, 2012, February).

References and Resources

Academy of Nutrition and Dietetics. (n.d.). How to use a food thermometer. Home Food Safety. Retrieved from www.homefoodsafety.org/cook/ how-to-use-a-food-thermometer?reset=true.

Colorado State University Extension. (2013, February). Crockpot and slow cooker food safety. Fort Collins, CO: Author. Retrieved from www. farmtotable.colostate.edu/docs/crockpot-foodsafety.pdf.

USDA Food Safety and Inspection Service. (2011, October).Danger zone (40 °F – 140 °F). (Rev. ed.). Washington, DC: Author. Retrieved from www.fsis. usda.gov/shared/PDF/Danger_Zone.pdf.

USDA Food Safety and Inspection Service. (2012, February).Slow cookers and food safety. (Rev. ed.). Washington, DC: Author. Retrieved from www.fsis. usda.gov/shared/PDF/Slow_Cookers_and_Food_ Safety.pdf.

Find out more about Michigan Food Safety at www.msue.msu.edu/safefood.



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