TLDR: A bain-marie, also known as a water bath or double boiler, is a device used in cooking and other industries to gently heat or keep materials warm. It consists of two containers, one inside the other, with the outer container filled with water or another liquid. The heat from the water transfers to the inner container, allowing for controlled and even heating.
A bain-marie has a long history, with its name derived from the French term "bain de Marie" or "Mary's bath." It was invented by an ancient alchemist named Mary the Jewess, but the concept of using a water bath for heating was known even earlier.
The device itself is made up of two containers: an outer container that holds the water or liquid, and an inner container that holds the material to be heated. The inner container is placed inside the outer container, and the heat from the water bath gently warms the material inside. This method of heating is especially useful for delicate ingredients that require gentle and even heat, such as chocolate or custards.
In cooking, a bain-marie has various applications. It can be used to melt chocolate without burning it or to keep sauces warm without curdling them. It is also commonly used for baking cheesecakes to prevent them from cracking and for cooking custard desserts to ensure they cook evenly. Additionally, a bain-marie can be used for various other purposes, such as re-liquefying hardened honey or melting soap bases in soap-making.
There are different types of bain-marie, including traditional ones that use a liquid-filled outer container and electric ones that use dry heat. Electric bain-maries are often more energy-efficient and easier to clean, and they can operate at higher temperatures. They can also be used with hot water or steam for heating.
Overall, a bain-marie is a versatile and useful tool in the kitchen and other industries where gentle and controlled heating is required. It allows for precise temperature control and helps prevent overheating or burning of delicate ingredients.