A Pressure cooker is an hermetically sealed pot which produces steam heat to cook food quickly. The pressure cooker first appeared in 1679 as Papin's Digester, named for its inventor, French-born physicist Denis Papin. The cooker heats water to produce very hot steam which forces the temperature inside the pot as high as 266 °F (130 °C), significantly higher than the maximum heat possible in an ordinary saucepan. The higher temperature of a pressure cooker penetrates food quickly, reducing cooking time without diminishing vitamin and mineral content. Pressure cookers are especially useful at high altitudes, where they alleviate the problem of low temperature boiling caused by reduced atmospheric pressure.