Boiling

Boiling, a type of vacuum pump or at high altitudes. Boiling occurs in three characteristic stages, which are nucleate, transition and film boiling. These stages generally take place from low to high surface temperatures, respectively.

Nucleate boiling is characterized by the incipience and growth of bubbles on a heated surface, which rise from discrete points on a surface, whose temperature is only slightly above the liquid’s saturation temperature. In general, the number of boiling delay when heated over its boiling point, by starting to boil suddenly and violently.

When the surface temperature reaches a maximum value, the critical superheat, thermal conductivity, this vapor layer insulates the surface. This condition of a vapor film insulating the surface from the liquid characterizes film boiling.

Transition boiling may be defined as the unstable boiling, which occurs at surface temperatures between the maximum attainable in nucleate and the minimum attainable in film boiling.

The formation of cavitation and acoustic effects, such as the broad-spectrum hiss one hears in a kettle not yet heated to the point where bubbles roil the surface.

Boiling in cookery

In cookery, boiling is cooking food in boiling water, or other water-based liquid such as stock or milk. Simmering is gentle boiling, while in poaching the cooking liquid moves but scarcely bubbles.

In places where the available microorganisms.

The temperature of a substance is constant as it undergoes a freezing point depression. Due to variations in composition and pressure, the boiling point of water is almost never exactly 212 F / 100 C, but rather close enough for cooking.

Foods suitable for boiling include:

Fish
Vegetables
Farinaceous foods such as pasta
Eggs
Meats
Sauces
Stocks and soups

Advantages:

Older, tougher, cheaper cuts of meat and poultry can be made digestible
It is appropriate for large-scale cookery
Nutritious, well flavoured stock is produced
It is safe and simple
Maximum color and nutritive value is retained when cooking green vegetables, provided boiling time is kept to the minimum

Disadvantages:

There is a loss of soluble vitamins in the water
Boiling water with the lid on wears out the pot
It can be a slow method
Foods can look unattractive

Boiling can be done in two ways: The food can be placed into already rapidly boiling water and left to cook, the heat can be turned down and the food can be simmered; or the food can also be placed into the pot, and cold water may be added to the pot. This may then be boiled until the food is satisfactory.

Water on the outside of a pot, i.e. a wet pot, actually increases the time it takes the pot of water to boil. The pot will heat at a normal rate once all excess water on the outside of the pot evaporates.

Boiling for water purification

Boiling is used as a method of water purification. Boiling is commonly advocated as an emergency water treatment method, or as a method of portable water purification in rural or wilderness settings without access to a potable water infrastructure.

Boiling as a means of execution

See also: Boiling to death