You can just throw in a bunch of ingredients and let your slow cooker e do its thing while you’re working on running errands. When it’s dinner time, you’ll have a dish that’s been stewing in delicious flavors for hours. However, here are several foods you should never put in. Some carry health risks, while others just won’t taste good.
Shellfish
Besides potentially stinking up your slow cooker, there’s another good reason you should avoid putting shellfish in the appliance. Chef and recipe creator Jessica Randhawa explains that shellfish “cooks really quickly, which is the opposite of what a slow cooker is designed to do. When slow-cooked, the fragile shellfish meat tends to disintegrate.”
Although regular fish is a bit heartier, she also recommends keeping it out of the slow cooker, because it’s still fairly delicate and “tends to break apart when slow-cooked easily.”
Frozen meat
The U.S. Department of Agriculture (USDA) warns against placing any frozen meat in your slow cooker. “Always defrost meat or poultry before putting it in the slow cooker,” the agency says. “If you place frozen meat or poultry in a slow cooker, it can spend too much time thawing, allow bacteria to multiply, and make you sick.” Using defrosted food will also ensure that your meal cooks evenly and all the way through, the USDA notes.
Hot chiles
While popping a handful of hot chiles into your slow cooker may seem like a simple way to add some flavor to your dish, it could backfire on you. Randhawa warns that this added spice should be used with caution, because “the capsicum tends to disperse over the entire pot over the extended slow cooking process.” Since it’s nearly impossible to remove excess heat, she suggests, “If you are unsure about how hot certain chili peppers are, it’s better to go light if the recipe calls for them initially and add more towards the end of the cooking time if you still want more heat when taste testing.”
Dry beans
Beans are a key ingredient in many beloved slow cooker recipes, from chilis to soups. However, the U.S. Food and Drug Administration (FDA) warns against tossing beans in your slow cooker without properly preparing them first. In the FDA’s “Bad Bug Book,” the agency explains that beans contain toxins called lectins, and slow cookers don’t get hot enough to destroy them.
Before pouring beans into your slow cooker, you need to break down the toxins. The FDA cites a U.K.-based study that says beans should be soaked in water for at least five hours. Then you should swap the water for fresh water and boil the beans for at least 30 minutes. Once this process is complete, you can safely add the beans to your slow cooker.
Milk
Plenty of recipes call for milk to help make your dish a bit creamier. However, experts say you should avoid using milk in a slow cooker—and if you must, you need to be strategic about the amount and timing of the addition. “Milk and other dairy products should not be slow-cooked because the slow, prolonged cooking could cause them to separate and curdle,” says food science expert Divya Raj.
Chef and recipe developer Devan Cameron suggests that, “If you really must add dairy to the slow cooker, add it at the end of the cooking.” If you add it too soon, it’ll make your dish chunky with curdled milk.
Wine
Cooking with wine is a common practice when preparing food on the stovetop or in the oven. However, if a recipe calls for wine in a slow cooker, you may want to avoid it. “Any recipe calling for wine shouldn’t be slow-cooked,” Raj wants. Unlike a stovetop or oven where alcohol can burn off or reduce, “The alcohol won’t have an outlet when it evaporates. So, your dish will taste funny.”
Water-based vegetables
Vegetables often help fill out a recipe, but some veggies won’t hold up well in a slow cooker. Experts warn against putting water-based vegetables, such as cauliflower, eggplant, zucchini, or broccoli, in one of these devices.
Recipe connoisseur Laura Ritterman says that if you must put them in the slow cooker, you should add them later on, so they spend less time stewing. “These vegetables cook quickly, and if heated for the majority of the day, will become mush,” she says.