How Slow Cookers Work

The Slow Cooker Device: How It Cooks

The slow cooker was developed from an electrical bean pot, a pot that was invented in the 1960s to steep dry beans. Small-appliance manufacturer West Bend produced The Electric Bean Pot, which spawned a copycat product by rival Naxon Utilities Corporation called The Beanery. The Rival company, today owned by Jarden, acquired Naxon and in 1971 released a reworked Beanery as the Crock-Pot, a slow cooker that could produce full meals in one pot. The Crock-Pot took off as a time-and-money-saving device for career women who still wanted to cook, and the brand became as ubiquitous as Kleenex. In fact, a 2002 Betty Crocker Kitchen study showed that more than 80 percent of U.S. households owned at least one slow cooker [Source: Bittman]

A slow cooker has three main components:

  • An outer casing
  • An inner container
  • A lid

The outer casing is metal and contains low-wattage heating coils, the component responsible for cooking the food, and these heating coils are completely encapsulated by the outer casing. The inner container, which is also called a crock, is made of glazed ceramic and fits inside the metal heating element. In some models, you can remove this cooking crock from the outer shell. The third piece of the appliance is a domed lid that fits tightly onto the crock.

The appliance cooks based on a combination of wattage and time. When turned on, the electrical coils heat up and transfer heat indirectly from the outer casing to the space between the base wall and the stoneware container. This indirect heat warms the crock to between 180 and 300 degrees Fahrenheit (82 to 149 degrees Celsius). This method of heat transfer simmers the ingredients inside the crock at a low temperature for several hours, until the food is thoroughly cooked.

As the food cooks, it releases steam, which the lid traps. The condensation creates a vacuum seal between the lid and the rim of the crock, which adds moisture to the food while helping the cooking process -- the lid is integral to the cooking process. The slow cooker typically has three settings: low, high and off. In programmable slow cookers, the device will switch to a warm setting after it has cooked the food to keep the meal at a proper temperature.