A slow cooker, also known as a crock-pot (after a trademark owned by Sunbeam Products but sometimes used generically in the English-speaking world), is a countertop electrical cooking appliance used to simmer at a lower temperature than other cooking methods, such as baking, boiling, and frying. This facilitates unattended cooking for many hours of dishes that would otherwise be boiled: pot roast, soups, stews and other dishes (including beverages, desserts and dips).
History
Slow cookers achieved popularity in the US during the 1940s, when many women began to work outside the home. They could start dinner cooking in the morning before going to work and finish preparing the meal in the evening when they came home.
The Naxon Utilities Corporation of Chicago, under the leadership of electrical engineer Irving Naxon (born Irving Nachumsohn), developed the Naxon Beanery All-Purpose Cooker for the purposes of cooking a bean meal. Naxon was inspired by a story from his mother which told how back in her native Lithuanian town, his grandmother made a traditional Jewish stew called cholent which took several hours to cook in an oven. A 1950 advertisement shows a slow cooker called the "Simmer Crock" made by the Industrial Radiant Heat Corp. of Gladstone, NJ.
The Rival Company from Sedalia, Missouri, bought Naxon in 1970, acquiring Naxon's 1940 patent for the bean simmer cooker. Rival asked inventor Robert Glen Martin, from Boonville, Missouri, to develop Naxon's bean cooker into a large scale production model which could cook an entire family meal, going further than just cooking a bean meal. Martin also designed and produced the mass-production machines for Rival's manufacturing line of the Crock-Pot. The cooker was then reintroduced under the name "Crock-Pot" in 1971. In 1974, Rival introduced removable stoneware inserts, making the appliance easier to clean. The Crock-Pot brand now belongs to Newell Brands.
Other brands of this appliance include Cuisinart, GE, Hamilton Beach, KitchenAid, Magic Chef, West Bend Housewares, and the now defunct American Electric Corporation.
Design
A basic slow cooker consists of a lidded round or oval cooking pot made of glazed ceramic or porcelain, surrounded by a housing, usually metal, containing an electric heating element. The lid itself is often made of glass, and seated in a groove in the pot edge; condensed vapor collects in the groove and provides a low-pressure seal to the atmosphere. The contents of a crock pot are effectively at atmospheric pressure, despite the water vapor generated inside the pot. A slow cooker is quite different from a pressure cooker and presents no danger of an abrupt pressure release.
The "crock", or ceramic pot, itself acts as both a cooking container and a heat reservoir. Slow cookers come in capacities from to . Because the heating elements are generally located at the bottom and often also partway up the sides, most slow cookers have a minimum recommended liquid level to avoid uncontrolled heating. Some newer models have coated aluminum or steel "crocks" which, while not as efficient as ceramic at retaining heat, do allow for quicker heating and cooling as well as the ability to use the "crock" on the stove top to brown meat prior to cooking.
Many slow cookers have two or more heat settings (e.g., low, medium, high, and sometimes a "keep warm" setting); some have continuously variable power. In the past, most slow cookers had no temperature control and deliver a constant heat to the contents. The temperature of the contents rises until it reaches boiling point, at which point the energy goes into gently boiling the liquid closest to the hot surface. At a lower setting, it may just simmer at a temperature below the boiling point. While many basic slow cookers still operate in this manner, newer models have computerized controls for precise temperature control, delayed cooking starts and control via a computer or mobile device.
Operation
To use a slow cooker, the cook places raw food and a liquid, such as stock, water, or wine, in the slow cooker. Some recipes call for pre-heated liquid. The cook puts the lid on the slow cooker and turns it on. Some cookers automatically switch from cooking to warming (maintaining the temperature at ) after a fixed time or after the internal temperature of the food, as determined by a probe, reaches a specified value.