Slow cooker

A slow cooker, often called a crock-pot (a trademark of Sunbeam Products, though the term is used generically in many English-speaking places), is an electric countertop appliance that cooks food at a lower temperature than methods like baking, boiling, or frying. This allows for unattended cooking over several hours, making it ideal for dishes that are typically boiled, such as pot roast, soups, stews, and even beverages, desserts, and dips.

History

The appliance became popular in the United States during the 1940s, when many women entered the workforce and could start dinner cooking in the morning before leaving for work, finishing the meal in the evening upon returning home. The Naxon Utilities Corporation in Chicago, led by electrical engineer Irving Naxon (born Irving Nachumsohn), created the Naxon Beanery All-Purpose Cooker specifically for cooking bean dishes. Naxon was inspired by his mother’s story of his grandmother making cholent, a traditional Jewish stew that cooked for hours in an oven in her native Lithuanian town. A 1950 advertisement also shows a "Simmer Crock" from the Industrial Radiant Heat Corporation of Gladstone, New Jersey.

In 1970, the Rival Company of Kansas City, Missouri, bought Naxon, acquiring his 1940 patent for the bean simmer cooker. Rival then asked inventor Alex MacMaster of Boonville, Missouri, to develop the bean cooker into a large-scale production model capable of cooking an entire family meal, going beyond just beans. MacMaster also designed and built the mass-production machines for Rival’s manufacturing line. The cooker was reintroduced under the trademark "Crock-Pot" in 1971.

In 1974, Rival introduced removable stoneware inserts, making cleaning easier. The Crock-Pot brand is now owned by Newell Brands. Other brands, past and present, include Cuisinart, GE, Hamilton Beach, KitchenAid, Magic Chef, West Bend Housewares, and the now-defunct American Electric Corporation.

Design

A basic slow cooker has a lidded round or oval cooking pot made of glazed ceramic or porcelain, surrounded by a metal housing containing an electric heating element. The lid is usually glass and sits in a groove in the pot’s edge, where condensed vapor collects and seals the pot. The contents remain at atmospheric pressure, unlike a pressure cooker, so there is no risk of abrupt pressure release.

The ceramic pot acts as both a cooking container and a thermal reservoir. Capacities range from 500 mL to 7 L. Because heating elements are typically at the bottom and sometimes partway up the sides, most models require a minimum liquid level to prevent uncontrolled heating. Some newer models have coated aluminum or steel "crocks" that heat and cool faster and can be used on a stovetop to brown meat before cooking.

Many slow cookers have two or more heat settings (low, medium, high, and sometimes "keep warm"), while some have continuously variable power. Early models had no temperature control and delivered constant heat, causing the contents to rise to a boil. At lower settings, the food may simply simmer below boiling. Newer models include electronics for precise temperature control, delayed starts, and control via computer or mobile device.

Operation

To use a slow cooker, raw food and a liquid (such as stock, water, or wine) are placed inside; some recipes call for pre-heated liquid. The lid is put on, and the cooker is turned on. Some cookers automatically switch from cooking to warming (maintaining 71–74°C) after a set time or when a probe detects a specific internal temperature. The heating element keeps the contents at a steady 79–93°C. The enclosed crock and lid maintain a constant temperature, with vapor condensing on the lid and returning as liquid, which leaches some water-soluble vitamins.

The liquid transfers heat and distributes flavors. The lid is essential to prevent warm vapor from escaping. Basic cookers have manual settings (high, medium, low, or keep warm), while advanced models have programmable timers for multiple operations (e.g., two hours high, then two hours low, then warm) and delayed starts. Because food stays warm long after being switched off, slow cookers can be used to transport meals without reheating; some lids seal to prevent spills.