Double boiler
Encyclopedia
A double boiler, also known as a bain Marie, is a stove top apparatus used to cook delicate sauces such as beurre blanc
, to melt chocolate
without burning or seizing, or cook any other thick liquid or porridge
that would normally burn if not stirred constantly. It consists of an upper vessel containing the substance to be cooked that is situated above a lower pot of water. When brought to a boil, the steam produced in the lower pot transfers heat to the upper pot.
This apparatus utilizes the properties of water to establish a constant temperature. The phase change of water from liquid to vapor occurs at 100°C (212°F). Therefore, as long as the lower pot does not become pressurized or boiled dry, the maximum temperature contacted by the upper vessel will be the boiling point
of water, and scalding or uneven heat is avoided. The steam will either condense on the upper vessel or escape, but the temperature of the vapor phase will remain constant. In order to maximize the efficiency of the heat transfer
process, the base of the upper vessel is constructed of a thinner, lower-gauge metal than the lower pot.
The lid on the upper vessel must fit tightly, or else steam may enter the upper vessel and affect the cooking substance. Manufacturers usually design the upper vessel and the lower pot as a set, a single lid fitting both.
Beurre blanc
Beurre blanc —literally translated from French as "white butter"— is a hot emulsified butter sauce made with a reduction of vinegar and/or white wine and grey shallots into which cold, whole butter is blended off the heat to prevent separation. The small amounts of lecithin and other emulsifiers...
, to melt chocolate
Chocolate
Chocolate is a raw or processed food produced from the seed of the tropical Theobroma cacao tree. Cacao has been cultivated for at least three millennia in Mexico, Central and South America. Its earliest documented use is around 1100 BC...
without burning or seizing, or cook any other thick liquid or porridge
Porridge
Porridge is a dish made by boiling oats or other cereal meals in water, milk, or both. It is usually served hot in a bowl or dish...
that would normally burn if not stirred constantly. It consists of an upper vessel containing the substance to be cooked that is situated above a lower pot of water. When brought to a boil, the steam produced in the lower pot transfers heat to the upper pot.
This apparatus utilizes the properties of water to establish a constant temperature. The phase change of water from liquid to vapor occurs at 100°C (212°F). Therefore, as long as the lower pot does not become pressurized or boiled dry, the maximum temperature contacted by the upper vessel will be the boiling point
Boiling point
The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....
of water, and scalding or uneven heat is avoided. The steam will either condense on the upper vessel or escape, but the temperature of the vapor phase will remain constant. In order to maximize the efficiency of the heat transfer
Heat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
process, the base of the upper vessel is constructed of a thinner, lower-gauge metal than the lower pot.
The lid on the upper vessel must fit tightly, or else steam may enter the upper vessel and affect the cooking substance. Manufacturers usually design the upper vessel and the lower pot as a set, a single lid fitting both.