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6 Common Slow Cooker Mistakes That Could Make You Sick

Avoid foodborne illness with these tips

spinner image beef casserole and vegetables cooked in a slow cooker on a wooden table that could lead to foodborne illness due to improper temperatures and cooking methods
S.FRENCH / Getty Images

Slow cookers are a convenient and popular tool for busy home cooks, and they have a reputation for cooking food safely. But as with any type of cooking potential dangers exist, making it important to follow kitchen safety guidelines to avoid getting food poisoning.​​

“A slow cooker is designed to cook foods that have moisture. It’s heating [food] up enough that it’s creating steam inside, which will help make an environment that bacteria can’t really produce or thrive in,” said Meredith Carothers, a public affairs specialist at the U.S. Department of Agriculture.

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Still, that isn’t an absolute guarantee against bacteria developing in slow-cooked food, and that can cause serious illnesses leading to hospitalization or even death, particularly among older adults. That’s why it’s important that even the most seasoned home chefs take precautions when using a slow cooker. By avoiding these six common mistakes, you can prepare meals that are not only nourishing and delicious but safe too.

1. You put frozen ingredients into the slow cooker

Placing frozen meats, vegetables or prepared meals in a slow cooker is not recommended, as it may take them too long to fully thaw and begin cooking. This can mean leaving the food at an unsafe temperature for an extended period of time, which can allow bacteria to grow and potentially cause illness, said Carothers.

Instead, it is best to first thaw frozen ingredients, including any “dump and go” meals, in the refrigerator, cold water or in the microwave. The only exception is if you are using a commercially prepared slow-cooked meal that instructs you to place the ingredients in the slow cooker while they’re still frozen.

2. You overfilled your slow cooker

To ensure proper cooking, it is important to fill your slow cooker with the appropriate amount of food. Aim for between half and two-thirds full. If the cooker is too full, the food may not cook evenly and could end up being undercooked. On the other hand, if the cooker is not full enough, the food may overcook. When adding ingredients, keep in mind that vegetables cook more slowly than meat and poultry, so it is best to place them in the bottom of the pot.

3. You reheated cooked food in the slow cooker

Similar to the risks associated with cooking frozen food in a slow cooker, the danger of reheating cooked foods in a slow cooker is that it may take too long to reheat them to a safe temperature.

“When it’s cooking, there’s that time-temperature relationship that cooks it within a certain amount of time versus reheating it,” said Carothers. “It’s just an extra safety measure to make sure that you’re reheating something quickly and efficiently versus putting it into a slow cooker.”


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4. You opened the lid too many times

Every time you remove the lid from your slow cooker, you release the steam that has built up inside, which may affect the cooking process. It takes approximately 30 minutes for the steam to build back up, so try to minimize the number of times you lift the lid during cooking.

5. You cooked your food on warm or switched to the warm setting too early

Once your meal is cooked, the warm setting may be kept on indefinitely. But you don’t want to cook raw ingredients on the warm setting. Use a food thermometer to make sure your food has reached the proper internal temperature before switching the pot to warm.

6. Your food sat in the slow cooker too long before you turned it on

You may want to delay starting your slow-cooked meal, but be cautious about relying on a timer to begin the cooking process. If the ingredients have been sitting out for less than an hour, it should be safe to proceed as planned. However, if the ingredients have been sitting out for between one and two hours, it is best to switch to a faster cooking method to ensure food safety. If the ingredients have been sitting out for more than two hours, they should be thrown away. 

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