How Slow Cookers Function

Important Points to Note

It's another chilly day, and after a long, exhausting workday, the last thing you want to do is spend hours cooking dinner. Thankfully, you've planned ahead, so as you walk into your home, the inviting aroma of a stew fills the air, leading you to a warm, ready-to-eat meal.

Even though no one’s home, your meal is nearly done thanks to your slow cooker. This small appliance, a household favorite for over 30 years, operates on the concept of slow cooking. The idea behind slow cooking is straightforward: Place food in a container and let it cook at a slow pace. This method, used in barbecue pits and pig roasts, allows meat to become tender by cooking at low temperatures over time. Slow cooking can be done with dry heat, like in an oven or roaster, or with moisture by incorporating liquid during the process. Slow cookers use moisture in a unique way by remaining sealed, causing steam from the cooking food to condense inside and act as a baster.

The slow cooking technique has existed for centuries, and the electrical slow cooker first gained popularity in the 1970s kitchens, where original models featured trendy colors like avocado and goldenrod. However, with the rise of microwaves in the following years, the slow cooker faded as people opted for quick heating. Recently, slow cooking has made a comeback, with new cookbooks offering a variety of delicious recipes for this versatile appliance. Manufacturers have created updated, more fashionable versions, making slow cookers a must-have for busy cooks. Next, we’ll explore how a pot designed for cooking beans changed the way we prepare food.

The Slow Cooker: How It Works

The slow cooker originated from an electric bean pot, a device created in the 1960s for cooking dry beans. West Bend, a small-appliance company, developed The Electric Bean Pot, which led to a rival product by Naxon Utilities Corporation called The Beanery. Later, in 1971, Naxon was acquired by Rival, now owned by Jarden, and they introduced the Crock-Pot, a reworked version of The Beanery that could prepare full meals in one pot. The Crock-Pot became a time- and money-saving solution for career women who still wanted to cook, and the brand became as well-known as Kleenex. A 2002 Betty Crocker Kitchen study found that over 80 percent of U.S. households owned at least one slow cooker [Source: Bittman].

A slow cooker consists of three main components:

The outer casing is made of metal and houses low-wattage heating coils, which are responsible for cooking the food. These coils are fully enclosed within the outer casing. The inner container, also known as the crock, is crafted from glazed ceramic and fits snugly inside the metal heating element. In some models, this cooking crock can be removed from the outer shell. The third component is a domed lid that seals tightly onto the crock.

The appliance operates by using a combination of wattage and time. When powered on, the electrical coils heat up, transferring heat indirectly from the outer casing to the area between the base wall and the stoneware container. This indirect heat raises the temperature of the crock to between 180 and 300 degrees Fahrenheit (82 to 149 degrees Celsius). The heat transfer method gently simmers the ingredients inside the crock over several hours, ensuring the food is fully cooked.

As the food cooks, steam is released, and the lid traps it. This condensation forms a vacuum seal between the lid and the rim of the crock, which not only adds moisture to the food but also aids in the cooking process – making the lid a key part of the process. Typically, the slow cooker has three settings: low, high, and off. In programmable models, the appliance switches to a warm setting once cooking is complete to maintain the food at an ideal temperature.

Advantages of Using a Slow Cooker

Using a slow cooker is an excellent way to save time while still preparing a healthy meal. You can put together the meal in the morning, set it in the slow cooker, and by evening, your dinner will be ready — with minimal mess and fewer dishes to clean up. The device consumes very little electricity to operate — in comparison to a regular oven, a slow cooker is far more energy-efficient, so it won't warm up your entire kitchen like an oven would.

Cooking with a slow cooker is also a budget-friendly option, allowing you to use less expensive cuts of meat. The condensation inside the cooker acts as a natural baster, helping tougher cuts of meat become tender. Plus, saving time and money doesn’t mean sacrificing flavor. Vegetables cooked in a slow cooker absorb stocks and spices, resulting in rich, deep flavors.

The high and low settings on the slow cooker let you adjust the cooking temperature based on how long you want the meal to cook. While cooking on low is perfectly safe, if you’re home during the process, the U.S. Department of Agriculture recommends starting on high for one hour to ensure the food is fully cooked.

Ideas for Cooking in a Slow Cooker

Meat is one of the most common ingredients used in a slow cooker, but it should be thawed beforehand to avoid extended cooking times. It's crucial to heat the meat to 140°F (60°C) as quickly as possible to eliminate any bacteria. Always ensure the internal temperature of the meat reaches the recommended level before serving. When cooking poultry, leave the skin on to help retain moisture during the cooking process.

Vegetable preparation for slow cooking might take longer than the meat preparation. It's essential to cut them into uniform pieces for even cooking. Since vegetables often take longer to cook than meat, when making stews or dishes that include both meat and vegetables, it's best to place the vegetables at the bottom of the pot.

Soups and stews are some of the best meals for a slow cooker since it is designed to simmer ingredients on the low setting for extended periods. Make sure to cover the soup ingredients with water, and if additional liquid is needed, bring it to a boil before adding it. This ensures the soup’s temperature remains stable throughout the cooking process.

Slow cookers are also perfect for making dips and spreads. The low heat ensures cheese-based dips stay warm without burning, and it prevents ingredients from solidifying during a party.

Grains can be an unexpected yet fantastic use for a slow cooker. Oatmeal, cracked wheat, and rice porridge can be prepared overnight for a warm and healthy breakfast. You can even bake bread and bread-based dishes like stuffing in a slow cooker – the gentle heat helps the dough rise. Surprisingly, slow cookers are also perfect for making desserts. While rice and tapioca puddings are a given, you can also prepare hot fruit desserts and even cakes.

Some recipes require adding certain ingredients towards the end of cooking due to their sensitivity to the slow-cooking process. Spices and herbs can become overly concentrated, so it's best to adjust their amounts later on. Additionally, certain vegetables, dairy, and seafood can lose their flavor and texture if cooked for too long. Always follow the instructions closely if the recipe recommends adding these ingredients at the end.

Slow Cooker Safety

Slow cookers are designed for long hours of cooking, ensuring that food is heated thoroughly, but it's still important to observe a few safety guidelines.

Never fill the stoneware pot more than two-thirds full, and always keep the lid on during cooking to maintain optimal conditions inside. Periodically check the cooker to confirm it is heating properly and cooking food to the correct temperature. To prevent bacteria growth, ensure that food reaches at least 140°F (60°C) within four hours.

To check if your slow cooker is working properly, fill it halfway to two-thirds full with water, cover it with the lid, and cook on the low setting for eight hours. Then, use a food thermometer to measure the temperature of the water before it cools down. If it reaches 185°F (85°C) or higher, the slow cooker is functioning safely. A lower temperature could indicate that the heating element isn't effectively heating the food [source: Peterson-Vangsness, Glenyce].

Since slow cookers operate on low wattage, it is safe to leave the house while the cooker is running. While the base does get warm, the design ensures it doesn't heat to the point of causing a countertop fire.

Never submerge the base of your slow cooker in water. If your cooker doesn't have a removable insert, use a soapy sponge to clean the interior and wipe off any spills.

Temperature shifts can crack the stoneware insert, so avoid freezing it or placing it over direct heat like a stovetop. Also, never place a hot crock directly on a cold counter -- use a hot pad to protect the ceramic. Additionally, avoid pouring cold water into a hot pot.

Always fully thaw meat and poultry before adding them to the slow cooker. Before serving, use a thermometer to confirm the meat is cooked to a safe temperature.

When cooking with beans, it's important to remember that dry beans, particularly dry red kidney beans, shouldn't be used in a slow cooker. These beans contain a toxin known as Phytohaemagglutinin, which can lead to nausea, vomiting, diarrhea, and stomach pain. Soaking and boiling dry beans removes the toxin and makes them safe to eat, but since slow cookers don't reach high enough temperatures to sufficiently heat dry beans, it's crucial to prepare them properly beforehand. To make dry beans safe, soak them for at least 12 hours, rinse, and then boil them for 10 minutes. Alternatively, you can use canned beans, which have already been boiled before canning [source: U.S. Food and Drug Administration].

A slow cooker should only be used for cooking, not reheating. Leftovers should be placed in shallow containers and refrigerated within two hours of serving. To reheat, use a stovetop or microwave, and ensure the food reaches a temperature of 165°F (74°C).