Operation
Raw food and a liquid (such as water, wine, or stock) are placed in the slow cooker. Some recipes call for pre-heated liquid. The cooker lid is put on and the cooker is switched on. Some cookers automatically switch from cooking to warming (maintaining the temperature at 71–74 °C ) after a fixed time or after the internal temperature of the food, as determined by a probe, reaches a specified value.
The heating element heats the contents to a steady temperature in the 79–93 °C (175–200 °F) range. The contents are enclosed by the crock and the lid, and attain an essentially constant temperature. The vapor that is produced at this temperature condenses on the bottom of the lid and returns as liquid. Some water-soluble vitamins are leached into the liquid.
The liquid transfers heat from the pot walls to its contents, and also distributes flavours. A lid is essential to prevent warm vapour from escaping, taking heat with it and cooling the contents.
Basic cookers, which have only high, medium, low, or keep warm settings, have to be manually turned on and off. Others have settings for high and low (e.g., four hours high, eight hours low) which allow the cook to choose a cooking time after which the cooker switches to "keep warm" mode. The most advanced cookers have computerised timing devices that allow the cooker to be programmed to perform multiple operations (e.g. two hours high, followed by two hours low, followed by warm) and to delay the start of cooking.
Because food stays warm for a long time after switching off, slow cookers can be used to cook food to be taken to be eaten elsewhere without reheating. Some cookers have ways of sealing the lid to prevent the contents from spilling during transport.
Read more about this topic: Slow Cooker
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