View source for Chaff

{{short description|Protective casings of the seeds of cereal grain}}
{{other uses|Chaff (disambiguation)}}{{distinguish|Bran}}
[[File:Rice chaffs.jpg|300px|thumb|[[Rice]] chaff]]
'''Chaff''' ({{IPAc-en|tʃ|æ|f}}; {{IPAc-en|also|UK|tʃ|ɑː|f}})<ref>{{cite book |title=Cambridge Pronouncing Dictionary|author=Daniel Jones|editor1=Peter Roach |editor2=James Hartman |editor3=Jane Setter |publisher=Cambridge University Press|year=2006}}</ref> is dry, scale-like plant material such as the protective [[husk|seed casings]] of [[cereal grain]]s, the scale-like parts of flowers, or finely chopped [[straw]]. Chaff cannot be digested by humans, but it may be [[fodder|fed to livestock]], [[plough]]ed into soil, or burned.

==Etymology==
{{wiktionary|chaff|glume}}
"Chaff" comes from [[Middle English]] {{lang|enm|chaf}}, from [[Old English language|Old English]] {{lang|ang|ceaf}}, related to [[Old High German]] ''{{lang|goh|cheva}}'', "husk".

==Grain chaff==
[[Image:Usdaeinkorn1 Triticum monococcum.jpg|thumbnail|Spikelets of a hulled wheat, [[Einkorn wheat|einkorn]]]]In [[Poaceae|grass]]es (including [[cereal|cereals]] such as [[rice]], [[barley]], [[oat|oats]], and [[wheat]]), the ripe seed is surrounded by thin, dry, scaly [[bracts]] (called [[glume|glumes]], [[Lemma (botany)|lemmas]], and [[palea (botany)|paleas]]), forming a dry [[husk]] (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]],<ref name=Potts>Potts, D. T. (1996) ''Mesopotamia Civilization: The Material Foundations'' [[Cornell University Press]]. p. 62. {{ISBN|0-8014-3339-8}}.</ref> [[emmer]]<ref>Nevo, Eviatar & A. B. Korol & A. Beiles & T. Fahima. (2002) ''Evolution of Wild Emmer and Wheat Improvement: Population Genetics, Genetic Resources, and Genome...''. Springer. p. 8. {{ISBN|3-540-41750-8}}.</ref> and [[spelt]]<ref>Vaughan, J. G. & P. A. Judd. (2003) ''The Oxford Book of Health Foods''. [[Oxford University Press]]. p. 35. {{ISBN|0-19-850459-4}}.</ref> 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 so as to remove it is called "[[threshing]]" before "[[drying]]" – traditionally done by milling or pounding, making it finer like "[[flour]]". Separating remaining loose chaff from the grain is called "[[winnowing]]" – traditionally done by repeatedly tossing the grain up into a light wind, which gradually blows the lighter chaff away. This method typically uses a broad, plate-shaped basket or similar receptacle to hold and collect the winnowed grain as it falls back down.<ref>{{Cite web |title=What Is Chaff: Learn How To Winnow Seeds From Chaff |url=https://www.gardeningknowhow.com/edible/grains/general-grains/chaff-and-winnowing-information.htm |access-date=2022-10-07 |website=Gardening Know How |date=7 September 2019 |language=en}}</ref>

Domesticated grains such as [[durum wheat|durum]] and [[common wheat]] have been bred to have chaff that is easily removed. These varieties are known as "free-threshing" or "naked".<ref>{{Cite web |title=Cereals & Grains Association |url=https://www.cerealsgrains.org/Pages/default.aspx |access-date=2024-07-11 |website=www.cerealsgrains.org |language=en-US}}</ref><ref>{{Cite journal |last1=Tzarfati |first1=Raanan |last2=Saranga |first2=Yehoshua |last3=Barak |first3=Vered |last4=Gopher |first4=Avi |last5=Korol |first5=Abraham B. |last6=Abbo |first6=Shahal |date=September 2013 |title=Threshing efficiency as an incentive for rapid domestication of emmer wheat |journal=Annals of Botany |volume=112 |issue=5 |pages=829–837 |doi=10.1093/aob/mct148 |issn=0305-7364 |pmc=3747801 |pmid=23884398}}</ref><ref>{{Cite journal |last=Watanabe |first=N. |date=2017-08-04 |title=Breeding opportunities for early, free-threshing and semi-dwarf Triticum monococcum L. |url=https://doi.org/10.1007/s10681-017-1987-0 |journal=Euphytica |language=en |volume=213 |issue=8 |article-number=201 |doi=10.1007/s10681-017-1987-0 |bibcode=2017Euphy.213..201W |issn=1573-5060|url-access=subscription }}</ref>

Chaff should not be confused with [[bran]], which is a finer, scaly material that is part of the grain itself.

==Straw chaff==
Chaff is also made by chopping [[straw]] (or sometimes coarse [[hay]]) into very short lengths, using a machine called a [[chaff cutter]]. Like grain chaff, it is used as animal feed and is a way of making coarse fodder more palatable for livestock.<ref>{{Cite web |url=http://www.dulwichpicturegallery.org.uk/collection/search/display.aspx?irn=56 |title=The Chaff cutter |access-date=2005-09-06 |archive-url=https://web.archive.org/web/20060103083512/http://www.dulwichpicturegallery.org.uk/collection/search/display.aspx?irn=56 |archive-date=2006-01-03 |url-status=dead }}</ref><ref>[http://www.antiquefarmtools.info/ Cutting chaff by hand]: detail of painting by [[David Teniers the Younger]]</ref><ref>[http://www.victorians.asp-host.co.uk/themes/agriculture/chaffcutterobj.htm A Victorian chaff cutter] {{webarchive |url=https://web.archive.org/web/20080321063813/http://www.victorians.asp-host.co.uk/themes/agriculture/chaffcutterobj.htm |date=March 21, 2008 }}</ref>

==Coffee chaff==
''Coffee chaff'' is produced from the so called ''silverskin'', the thin inner-parchment layer on dried coffee beans, in the process of [[coffee roasting]].

==Botany==
In [[botany]], chaff refers to the thin [[List of plant morphology terms#Basic flower parts|receptacular]] [[bracts]] of many species in the sunflower family [[Asteraceae]] and related families. They are modified scale-like [[leaves]] surrounding single [[floret]]s in the flower-head.<ref name="Jones2005">{{cite book|author=Ronald Jones|title=Plant Life of Kentucky: An Illustrated Guide to the Vascular Flora|url=https://books.google.com/books?id=Bsngx7s0OI4C&pg=PA751|date=25 March 2005|publisher=University Press of Kentucky|isbn=0-8131-7194-6|pages=751–}}</ref>

==Metaphor==
Chaff as a waste product from grain processing leads to a [[metaphor]]ical use of the term, to refer to something seen as worthless. In the [[Bible]], such use is found in Job 13:25,<ref>{{Cite web |title=Job 13:25 Would You frighten a windblown leaf? Would You chase after dry chaff? |url=https://biblehub.com/job/13-25.htm |access-date=2022-10-07 |website=biblehub.com}}</ref> Isaiah 33:11,<ref>{{Cite web |title=Bible Gateway passage: Isaiah 33:11 - New International Version |url=https://www.biblegateway.com/passage/?search=Isaiah%2033%3A11&version=NIV |access-date=2022-10-07 |website=Bible Gateway |language=en}}</ref> Psalm 83:13-15,<ref>{{Cite web |title=Bible Gateway passage: Psalm 83:13-15 - New International Version |url=https://www.biblegateway.com/passage/?search=Psalm%2083%3A13-15&version=NIV |access-date=2022-10-07 |website=Bible Gateway |language=en}}</ref> and other places. Chaff also lends its name to [[Chaff (countermeasure)|a radar countermeasure]], composed of small particles dropped from an aircraft.{{cn|date=February 2023}}

==Use==
Hungarian engineer László Schremmer has discovered that the use of chaff-based filters can reduce the [[arsenic]] content of water to 3 microgram/litre. This is especially important in areas where the potable water is provided by filtering the water extracted from an underground [[aquifer]].<ref>[http://mno.hu/gazdasag/szenzacios-magyar-talalmany-1068315 Newspaper article] {{Webarchive|url=https://web.archive.org/web/20120417212726/http://mno.hu/gazdasag/szenzacios-magyar-talalmany-1068315 |date=2012-04-17 }} (in Hungarian) published by [[Magyar Nemzet]] on April 15, 2012.</ref>

==See also==
* [[Awn (botany)]]
* [[Bran]]
* [[Biomass]]
* [[Combine harvester]]
* [[Rice hulls]]
* [[Rice huller]]
* [[Sifting]]

==References==
{{reflist}}{{Wheat}}
[[Category:Plant morphology]]
[[Category:Fodder]]
[[Category:Waste]]

[[ca:Espícula#Glumel·les]]