Chaff

Chaff

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Chaff is the dry, scaly protective casings of the seeds of cereal grain, or similar fine, dry, scaly plant material such as scaly parts of flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

s, or finely chopped straw
Straw
Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...

. Chaff is inedible for humans, but livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...

 can eat it and in agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

 it is used as livestock fodder
Fodder
Fodder or animal feed is any agricultural foodstuff used specifically to feed domesticated livestock such as cattle, goats, sheep, horses, chickens and pigs. Most animal feed is from plants but some is of animal origin...

, or is a waste material plough
Plough
The plough or plow is a tool used in farming for initial cultivation of soil in preparation for sowing seed or planting. It has been a basic instrument for most of recorded history, and represents one of the major advances in agriculture...

ed into the soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 or burnt.

Etymology


"Chaff" comes from Middle English
Middle English
Middle English is the stage in the history of the English language during the High and Late Middle Ages, or roughly during the four centuries between the late 11th and the late 15th century....

 chaf, from Old English
Old English language
Old English or Anglo-Saxon is an early form of the English language that was spoken and written by the Anglo-Saxons and their descendants in parts of what are now England and southeastern Scotland between at least the mid-5th century and the mid-12th century...

 ceaf, related to Old High German
Old High German
The term Old High German refers to the earliest stage of the German language and it conventionally covers the period from around 500 to 1050. Coherent written texts do not appear until the second half of the 8th century, and some treat the period before 750 as 'prehistoric' and date the start of...

 cheva, "husk".

Grain chaff


In grass
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...

es (including cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

s such as rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

, barley
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...

, oat
Oat
The common oat is a species of cereal grain grown for its seed, which is known by the same name . While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed...

s and wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...

), the ripe seed is surrounded by thin, dry, scaly bracts (called glumes, lemma
Lemma (botany)
Lemma is a phytomorphological term used in botany referring to a part of the spikelet of grasses . It is the lowermost of two chaff-like bracts enclosing the grass floret. It often bears a long bristle called an awn, and may be similar in form to the glumes - chaffy bracts at the base of each...

s and palea
Palea (botany)
Palea, in botany, refers to one of the bract-like organs of the grass spikelet . It is the uppermost of the two chaff-like bracts that enclose the grass floret . It is often cleft at the tip, implying that it may be a double structure derived from the union of two separate organs...

s), forming a dry husk
Husk
Husk in botany is the outer shell or coating of a seed. It often refers to the leafy outer covering of an ear of maize as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed, fruit or vegetable...

 (or hull) around the grain. Once it is removed it is often referred to as chaff.

In wild cereals and in the primitive domesticated einkorn, emmer
Emmer
Emmer wheat , also known as farro especially in Italy, is a low yielding, awned wheat. It was one of the first crops domesticated in the Near East...

 and spelt
Spelt
Spelt is a hexaploid species of wheat. Spelt was an important staple in parts of Europe from the Bronze Age to medieval times; it now survives as a relict crop in Central Europe and northern Spain and has found a new market as a health food. Spelt is sometimes considered a subspecies of the...

 wheats, the husks enclose each seed tightly. Before the grain can be used, the husks must be removed.

The process of loosening the chaff from the grain is called threshing
Threshing
Threshing is the process of loosening the edible part of cereal grain from the scaly, inedible chaff that surrounds it. It is the step in grain preparation after harvesting and before winnowing, which separates the loosened chaff from the grain...

– traditionally done by milling or pounding. Separating the loose chaff from the grain is called winnowing – traditionally done by tossing grain up into lightly blowing wind, dividing it from the lighter chaff, which is blown aside. This process typically utilizes a broad, plate-shaped basket, or similar receptacle for holding and collecting the winnowed grain as it falls back down.

Domesticated grains such as durum wheat and common wheat
Common wheat
Common wheat, Triticum aestivum, is a cultivated wheat species.-Nomenclature and taxonomy of the variety and its cultivars:-Evolution:...

 have been bred to have chaff which is easily removed. These varieties are known as free-threshing or naked.

Chaff should not be confused with bran
Bran
Bran is the hard outer layer of grain and consists of combined aleurone and pericarp. Along with germ, it is an integral part of whole grains, and is often produced as a by-product of milling in the production of refined grains. When bran is removed from grains, the grains lose a portion of their...

, which is finer scaly material forming part of the grain itself.

Straw chaff


Chaff is also made by chopping straw
Straw
Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...

 (or sometimes coarse hay
Hay
Hay is grass, legumes or other herbaceous plants that have been cut, dried, and stored for use as animal fodder, particularly for grazing livestock such as cattle, horses, goats, and sheep. Hay is also fed to pets such as rabbits and guinea pigs...

) into very short lengths, using a machine called a chaff cutter
Chaff cutter
Chaff cutter — a mechanical device for cutting straw or hay into small pieces — before being mixed together with other forage and fed to horses and cattle. This aids the animal's digestion and prevents animals from rejecting any part of their food....

. Like grain chaff this is used as animal feed, and is a way of turning coarse fodder into a form more palatable to livestock.

Botany


In botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

, chaff refers to the thin receptacular bracts of many species in the sunflower family Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...

 and related families. They are modified scale-like leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...

 surrounding single florets in the flower-head.

Metaphor


Chaff as a waste product from grain processing leads to a metaphor
Metaphor
A metaphor is a literary figure of speech that uses an image, story or tangible thing to represent a less tangible thing or some intangible quality or idea; e.g., "Her eyes were glistening jewels." Metaphor may also be used for any rhetorical figures of speech that achieve their effects via...

ical use of the term, to refer to something seen as worthless. This is commonly used in the expression "to separate the wheat from the chaff" from Matthew
Gospel of Matthew
The Gospel According to Matthew is one of the four canonical gospels, one of the three synoptic gospels, and the first book of the New Testament. It tells of the life, ministry, death, and resurrection of Jesus of Nazareth...

 3., where it means to separate things of value from things of no value. Another example is in Psalm 1 of the Bible
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...

, which says: "Not so the wicked! They are like chaff that the wind blows away".

See also


  • Bran
    Bran
    Bran is the hard outer layer of grain and consists of combined aleurone and pericarp. Along with germ, it is an integral part of whole grains, and is often produced as a by-product of milling in the production of refined grains. When bran is removed from grains, the grains lose a portion of their...

  • Biomass
    Biomass
    Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

  • Combine harvester
    Combine harvester
    The combine harvester, or simply combine, is a machine that harvests grain crops. The name derives from the fact that it combines three separate operations, reaping, threshing, and winnowing, into a single process. Among the crops harvested with a combine are wheat, oats, rye, barley, corn ,...

  • Threshing
    Threshing
    Threshing is the process of loosening the edible part of cereal grain from the scaly, inedible chaff that surrounds it. It is the step in grain preparation after harvesting and before winnowing, which separates the loosened chaff from the grain...

  • Threshing machine
    Threshing machine
    The thrashing machine, or, in modern spelling, threshing machine , was a machine first invented by Scottish mechanical engineer Andrew Meikle for use in agriculture. It was invented for the separation of grain from stalks and husks. For thousands of years, grain was separated by hand with flails,...

  • Winnowing