Editing Almond (section)

=== Sweet and bitter almonds ===
[[File:شکوفه سفید بادام.jpg|thumb|Almond blossom]]
[[File:Rose ringed Parakeet in bitter Almond.jpg|thumb|Blossoming of bitter almond tree]]

The seeds of ''Prunus dulcis'' var. ''dulcis'' are predominantly sweet<ref>{{cite web|last=Karl-Franzens-Universität (Graz)|title=Almond (Prunus dulcis [Mill.] D. A. Webb.)|url=http://www.uni-graz.at/~katzer/engl/Prun_dul.html|access-date=10 April 2011|archive-url=https://web.archive.org/web/20110514021042/http://www.uni-graz.at/~katzer/engl/Prun_dul.html|archive-date=14 May 2011|url-status=dead}}</ref><ref>{{cite web|title=Almond and bitter almond|url=http://www.chow.com/ingredients/265|work=from Quirk Books: www.quirkbooks.com|access-date=8 April 2011| archive-url= https://archive.today/20110511175227/http://www.chow.com/ingredients/265| archive-date= 11 May 2011 <!-- Bot inserted parameter. Either remove it; or change its value to "." for the cite to end in a ".", as necessary. -->| url-status= live}}</ref> but some individual trees produce seeds that are somewhat more bitter.<ref name="eb" /> The genetic basis for bitterness involves a single gene, the bitter flavour furthermore being [[Dominance (genetics)|recessive]],<ref>{{cite journal |last=Heppner |first=Myer J |date=7 April 1923 |title=The factor for bitterness in the sweet almond |journal=Genetics |volume=8 |issue=4 |pages=390–392 |doi=10.1093/genetics/8.4.390 |pmc=1200758 |pmid=17246020}}</ref><ref>{{cite journal |last1=Dicenta |first1=Federico |last2=Ortega |first2=Encarnacion |last3=Martinez-Gomez |first3=Pedro |s2cid=9893400 |date=January 2007 |title=Use of recessive homozygous genotypes to assess genetic control of kernel bitterness in almond |journal=Euphytica |publisher=Springer |volume=153 |issue=1–2 |pages=221–225 |doi=10.1007/s10681-006-9257-6 }}<!--|access-date=4 March 2014--></ref> both aspects making this trait easier to domesticate. The fruits from ''Prunus dulcis'' var. ''amara'' are always bitter, as are the kernels from other species of genus ''Prunus'', such as apricot, peach and cherry (although to a lesser extent).

The bitter almond is slightly broader and shorter than the sweet almond and contains about 50% of the fixed oil that occurs in sweet almonds. It also contains the enzyme [[emulsin]] which, in the presence of water, acts on the two [[Solubility|soluble]] [[glucoside]]s [[amygdalin]] and [[prunasin]]<ref>{{cite journal |vauthors=Sánchez-Pérez R, Belmonte FS, Borch J, Dicenta F, Møller BL, Jørgensen K |title=Prunasin hydrolases during fruit development in sweet and bitter almonds |journal=Plant Physiology |volume=158 |issue=4 |pages=1916–32 |date=April 2012  |pmid=22353576 |pmc=3320195 |doi=10.1104/pp.111.192021}}</ref> yielding [[glucose]], [[cyanide]] and the [[essential oil]] of bitter almonds, which is nearly pure [[benzaldehyde]], the chemical causing the bitter flavour. Bitter almonds may yield 4–9&nbsp;milligrams of [[hydrogen cyanide]] per almond<ref>{{cite journal |vauthors=Shragg TA, Albertson TE, Fisher CJ |title=Cyanide poisoning after bitter almond ingestion |journal=West. J. Med. |volume=136 |issue=1 |pages=65–9 |date=January 1982 |pmid=7072244 |pmc=1273391 }}</ref> and contain 42 times higher amounts of cyanide than the trace levels found in sweet almonds.<ref name="isrn">{{cite journal |journal=ISRN Toxicol |year=2013 |issue=19 September |page=610648 |doi=10.1155/2013/610648 |pmid=24171123 |title=Potential Toxic Levels of Cyanide in Almonds (Prunus amygdalus), Apricot Kernels (Prunus armeniaca), and Almond Syrup |vauthors=Chaouali N, Gana I, Dorra A, Khelifi F, Nouioui A, Masri W, Belwaer I, Ghorbel H, Hedhili A |pmc=3793392 |volume=2013|doi-access=free }}</ref> The origin of cyanide content in bitter almonds is via the [[enzymatic hydrolysis]] of amygdalin.<ref name="isrn"/> [[Cytochrome P450|P450]] [[monooxygenase]]s are involved in the amygdalin biosynthetic pathway. A point mutation in a [[Basic helix-loop-helix|bHLH]] [[transcription factor]] prevents [[Transcription (biology)|transcription]] of the two cytochrome P450 genes, resulting in the sweet kernel trait.<ref>{{Cite journal|last1=Sánchez-Pérez|first1=R.|last2=Pavan|first2=S.|last3=Mazzeo|first3=R.|last4=Moldovan|first4=C.|last5=Aiese Cigliano|first5=R.|last6=Del Cueto|first6=J.|last7=Ricciardi|first7=F.|last8=Lotti|first8=C.|last9=Ricciardi|first9=L.|s2cid=189818379|date=14 June 2019|title=Mutation of a bHLH transcription factor allowed almond domestication|journal=Science|language=en|volume=364|issue=6445|pages=1095–1098|doi=10.1126/science.aav8197|pmid=31197015|bibcode=2019Sci...364.1095S|issn=0036-8075|doi-access=free|hdl=11586/236719|hdl-access=free}}</ref>