Blanching
Encyclopedia
Blanching is a cooking
process wherein the food substance, usually a vegetable or fruit, is plunged into boiling
water, removed after a brief, timed interval, and finally plunged into iced water or placed under cold running water (shocked) to halt the cooking process.
The meaning of blanching is "to whiten", but this is not always the purpose of blanching in cooking. Food is blanched to soften it, or to partly or fully cook it, or to remove a strong taste (for example of bacon
, cabbage
, or onions).
When almond
s or pistachios are blanched, the skin of the nut (botanically the seed coat surrounding the embryo
) softens and can be easily removed later.
The technique of blanching vegetables is best illustrated by the requirement to stop cook asparagus
, otherwise it would become soggy due to the asparagus continuing to cook after it is removed from the boiling water. To cook asparagus using the blanching method, the shoots are boiled for 30 seconds, and then to stop the cooking instantly they are dipped into cold or ice water. The term "blanched asparagus" is also used for white asparagus. White asparagus is produced by a special gardening technique; the young preemerging shoots are covered with a paper bag to block out light and cause the unexposed white shoots to grow without chlorophyll
(some of the shoots from the plant must remain in sunlight and turn green, to keep the plant healthy).
Blanching may simply mean boiling in water for an extended period to remove unpleasant flavours such as tannin
s. For example, a recommended treatment for african yam bean (Sphenostylis
stenocarpa), is dehulling followed by blanching in water for 40 minutes at 100°C.
New York City Department of Health & Mental Hygiene Food Protection Training Manual (February 2010) recommends preparing Protein Type Salads (Tuna, Turkey, Ham, Shrimp, Lobster, and Chicken) by immersing these protein foods in boiling water for 30 seconds followed by fast chilling. In addition celery, "which is almost always a component of these salads ... should be treated so as to minimize its bacterial content".
Cooking
Cooking is the process of preparing food by use of heat. Cooking techniques and ingredients vary widely across the world, reflecting unique environmental, economic, and cultural traditions. Cooks themselves also vary widely in skill and training...
process wherein the food substance, usually a vegetable or fruit, is plunged into boiling
Boiling
Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding environmental pressure. While below the boiling point a liquid...
water, removed after a brief, timed interval, and finally plunged into iced water or placed under cold running water (shocked) to halt the cooking process.
The meaning of blanching is "to whiten", but this is not always the purpose of blanching in cooking. Food is blanched to soften it, or to partly or fully cook it, or to remove a strong taste (for example of bacon
Bacon
Bacon is a cured meat prepared from a pig. It is first cured using large quantities of salt, either in a brine or in a dry packing; the result is fresh bacon . Fresh bacon may then be further dried for weeks or months in cold air, boiled, or smoked. Fresh and dried bacon must be cooked before eating...
, cabbage
Cabbage
Cabbage is a popular cultivar of the species Brassica oleracea Linne of the Family Brassicaceae and is a leafy green vegetable...
, or onions).
When almond
Almond
The almond , is a species of tree native to the Middle East and South Asia. Almond is also the name of the edible and widely cultivated seed of this tree...
s or pistachios are blanched, the skin of the nut (botanically the seed coat surrounding the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
) softens and can be easily removed later.
The technique of blanching vegetables is best illustrated by the requirement to stop cook asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
, otherwise it would become soggy due to the asparagus continuing to cook after it is removed from the boiling water. To cook asparagus using the blanching method, the shoots are boiled for 30 seconds, and then to stop the cooking instantly they are dipped into cold or ice water. The term "blanched asparagus" is also used for white asparagus. White asparagus is produced by a special gardening technique; the young preemerging shoots are covered with a paper bag to block out light and cause the unexposed white shoots to grow without chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
(some of the shoots from the plant must remain in sunlight and turn green, to keep the plant healthy).
Other definitions
In the early 1960s, McDonald's Restaurant in Charlotte, North Carolina, used a process on their potatoes they called 'blanching.' After the potatoes were mechanically peeled and then manually pushed through a slicer producing raw French fries, they were batch-soaked in room-temperature water for 3–5 minutes to remove starch, which they called blanching.Blanching may simply mean boiling in water for an extended period to remove unpleasant flavours such as tannin
Tannin
A tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...
s. For example, a recommended treatment for african yam bean (Sphenostylis
Sphenostylis
Sphenostylis is a genus of flowering plants in the legume family, Fabaceae. It belongs to the sub family Faboideae....
stenocarpa), is dehulling followed by blanching in water for 40 minutes at 100°C.
New York City Department of Health & Mental Hygiene Food Protection Training Manual (February 2010) recommends preparing Protein Type Salads (Tuna, Turkey, Ham, Shrimp, Lobster, and Chicken) by immersing these protein foods in boiling water for 30 seconds followed by fast chilling. In addition celery, "which is almost always a component of these salads ... should be treated so as to minimize its bacterial content".
External links
- Free Culinary School Podcast Episode 3 A podcast discussing the importance of blanching and the science behind the technique.
- How to Blanch Almonds at about.com