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How Steam Cooking Works

Steam is an extremely efficient heat transfer medium. It carries a great deal of energy which readily transfers directly to food (in steamers) or indirectly through a heat transfer surface (such as a kettle wall) and then into food. Steam is water (a liquid) that has been converted to its gaseous state by the application of heat energy. Heat energy typically is measured in British Thermal Units (BTU). The BTU is defined as the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit at sea level. It takes only 180 BTUs to raise the temperature of one pound of water from 32F (0C) to 212F (100C), the point at which it starts to boil. However, to evaporate that same pound of boiling water into steam requires 970 BTUs. As a result, steam carries many times the energy of boiling water. Steam readily gives up that energy load when it condenses back into water (condensate) upon contact with the food.<br>