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Chemical tests in mushroom identification

Chemical tests in mushroom identification are methods that aid in determining the variety of some fungi. The most useful tests are Melzer's reagent and potassium hydroxide.

Ammonia edit

Household ammonia can be used. A couple of drops are placed on the flesh. For example, Boletus spadiceus gives a fleeting blue to blue-green reaction.

Iron salts edit

Iron salts are used commonly in Russula and Bolete identification. It is best to dissolve the salts in water (typically a 10% solution) and then apply to the flesh, but it is sometimes possible to apply the dry salts directly to see a color change. For example, the white flesh of Boletus chrysenteron stains lemon-yellow or olive. Three results are expected with the iron salts tests: no change indicates a negative reaction; a color change to olive, green or blackish green; or a color change to reddish-pink.[1]

Meixner test for amatoxins edit

The Meixner test (also known as the Wieland test) uses concentrated hydrochloric acid and newspaper to test for the deadly amatoxins found in some species of Amanita, Lepiota, and Galerina. The test yields false positives for some compounds, such as psilocin.[2]

Melzer's reagent edit

Melzer's reagent can be used to test whether spores are amyloid, nonamyloid, or dextrinoid.

  • Spores that stain bluish-gray to bluish-black are amyloid
  • Spores that stain brown to reddish-brown are dextrinoid

This test is normally performed on white spored mushrooms. If the spores are not light colored, a change will not be readily apparent. It is easiest to see the color change under a microscope, but it is possible to see it with the naked eye with a good spore print.

Paradimethylaminobenzaldehyde edit

In the genus Lyophyllum the lamellae usually turn blue with the application of para-Dimethylaminobenzaldehyde (PDAB or pDAB).

Phenol edit

A 2–3% aqueous solution of phenol gives a color change in some species when applied to the cap or stem.

Potassium hydroxide edit

A 3–10% solution of potassium hydroxide (KOH) gives a color change in some species of mushrooms:

Schaeffer reaction edit

Developed by Julius Schäffer to help with the identification of Agaricus species. A positive reaction of Schaeffer's test, which uses the reaction of aniline and nitric acid on the surface of the mushroom, is indicated by an orange to red color; it is characteristic of species in the section Flavescentes. The compounds responsible for the reaction were named schaefferal A and B to honor Schäffer.[3]

Two intersecting lines are drawn on the surface of the cap, the first with aniline or aniline water, the second with an aqueous solution of 65% nitric acid. The test is considered positive when a bright orange color forms where the lines cross.[4][5][6]

Agaricus placomyces and Agaricus xanthodermus produce false negative reactions.[4][5]

Sometimes referred to as "Schaeffer's reaction", "Schaeffer's cross reaction" or "Schaeffer's test".

Aniline + acid(s) edit

Kerrigan's 2016 Agaricus of North America P45: (Referring to Schaffer's reaction) "In fact I recommend switching to the following modified test. Frank (1988) developed an alternative formulation in which aniline oil is combined with glacial acetic acid (GAA, essentially distilled vinegar) in a 50:50 solution. GAA is a much safer, less reactive acid. This single combined reagent is relatively stable over time. A single spot or line applied to the pileus (or other surface). In my experience the newer formulation works as well as Schaffer's while being safer and more convenient."[7]

Sulfo-vanillin edit

Made from sulfuric acid (H2SO4) and vanillin (vanilla). Used in Russula and Panaeolus identification.

References edit

  1. ^ Ammirati J, Traquair JA, Horgen PA (1985). Poisonous Mushrooms of Canada. Fitzhenry & Whiteside in cooperation with Agriculture Canada. p. 40. ISBN 978-0-88902-977-4.
  2. ^ Beuhler, M; Lee, DC; Gerkin, R (2004). "The Meixner test in the detection of alpha-amanitin and false-positive reactions caused by psilocin and 5-substituted tryptamines". Annals of Emergency Medicine. 44 (2): 114–20. doi:10.1016/j.annemergmed.2004.03.017. PMID 15278082.
  3. ^ Kileci-Ksoll R, Winklhoer C, Steglich W (2010). "Synthesis of schaefferals A and B, unusual phenylhydrazine derivatives from mushrooms of the genus Agaricus". Synthesis. 2010 (13): 2287–91. doi:10.1055/s-0029-1218790.
  4. ^ a b Hui, Y. H.; Smith, R. A.; Spoerke, Jr., David G. (2000). Foodborne Disease Handbook, Second Edition: Volume 3: Plant Toxicants. CRC Press. p. 745. ISBN 978-0824703431.
  5. ^ a b Spoerke, David G.; Rumack, Barry H. (1994). Handbook of Mushroom Poisoning: Diagnosis and Treatment. CRC Press. p. 146. ISBN 978-0849301940.
  6. ^ Bresinsky, A; Besl, H (1990). A Colour Atlas Of Poisonous Fungi: A Handbook for Pharmacists, Doctors, and Biologists. CRC Press. ISBN 978-0723415763.
  7. ^ Kerrigan, Richard (2016). Agaricus of North America. NYBG Press. p. 45. ISBN 978-0-89327-536-5.
  • Arora, David "Mushrooms Demystified" 2nd Edition, Ten Speed Press, Berkeley, 1986
  • Jordan, Michael "The Encyclopedia of Fungi of Britain and Europe" Frances Lincoln 2004
  • Kuo, Michael "100 Edible Mushrooms", University of Michigan Press, Ann Arbor 2007
  • Largent, David L., Baroni, Timothy J. "How to Identify Mushrooms to Genus VI: Modern Genera" Mad River Press 1988

External links edit

  • MushroomExpert.com

chemical, tests, mushroom, identification, methods, that, determining, variety, some, fungi, most, useful, tests, melzer, reagent, potassium, hydroxide, contents, ammonia, iron, salts, meixner, test, amatoxins, melzer, reagent, paradimethylaminobenzaldehyde, p. Chemical tests in mushroom identification are methods that aid in determining the variety of some fungi The most useful tests are Melzer s reagent and potassium hydroxide Contents 1 Ammonia 2 Iron salts 3 Meixner test for amatoxins 4 Melzer s reagent 5 Paradimethylaminobenzaldehyde 6 Phenol 7 Potassium hydroxide 8 Schaeffer reaction 9 Aniline acid s 10 Sulfo vanillin 11 References 12 External linksAmmonia editHousehold ammonia can be used A couple of drops are placed on the flesh For example Boletus spadiceus gives a fleeting blue to blue green reaction Iron salts editIron salts are used commonly in Russula and Bolete identification It is best to dissolve the salts in water typically a 10 solution and then apply to the flesh but it is sometimes possible to apply the dry salts directly to see a color change For example the white flesh of Boletus chrysenteron stains lemon yellow or olive Three results are expected with the iron salts tests no change indicates a negative reaction a color change to olive green or blackish green or a color change to reddish pink 1 Meixner test for amatoxins editThe Meixner test also known as the Wieland test uses concentrated hydrochloric acid and newspaper to test for the deadly amatoxins found in some species of Amanita Lepiota and Galerina The test yields false positives for some compounds such as psilocin 2 Melzer s reagent editMelzer s reagent can be used to test whether spores are amyloid nonamyloid or dextrinoid Spores that stain bluish gray to bluish black are amyloid Spores that stain brown to reddish brown are dextrinoidThis test is normally performed on white spored mushrooms If the spores are not light colored a change will not be readily apparent It is easiest to see the color change under a microscope but it is possible to see it with the naked eye with a good spore print Paradimethylaminobenzaldehyde editIn the genus Lyophyllum the lamellae usually turn blue with the application of para Dimethylaminobenzaldehyde PDAB or pDAB Phenol editA 2 3 aqueous solution of phenol gives a color change in some species when applied to the cap or stem Potassium hydroxide editA 3 10 solution of potassium hydroxide KOH gives a color change in some species of mushrooms In Agaricus some species such as A xanthodermus turn yellow with KOH many have no reaction and A subrutilescens turns green Distinctive change occurs for some species of Cortinarius and BoletesSchaeffer reaction editDeveloped by Julius Schaffer to help with the identification of Agaricus species A positive reaction of Schaeffer s test which uses the reaction of aniline and nitric acid on the surface of the mushroom is indicated by an orange to red color it is characteristic of species in the section Flavescentes The compounds responsible for the reaction were named schaefferal A and B to honor Schaffer 3 Two intersecting lines are drawn on the surface of the cap the first with aniline or aniline water the second with an aqueous solution of 65 nitric acid The test is considered positive when a bright orange color forms where the lines cross 4 5 6 Agaricus placomyces and Agaricus xanthodermus produce false negative reactions 4 5 Sometimes referred to as Schaeffer s reaction Schaeffer s cross reaction or Schaeffer s test Aniline acid s editKerrigan s 2016 Agaricus of North America P45 Referring to Schaffer s reaction In fact I recommend switching to the following modified test Frank 1988 developed an alternative formulation in which aniline oil is combined with glacial acetic acid GAA essentially distilled vinegar in a 50 50 solution GAA is a much safer less reactive acid This single combined reagent is relatively stable over time A single spot or line applied to the pileus or other surface In my experience the newer formulation works as well as Schaffer s while being safer and more convenient 7 Sulfo vanillin editMade from sulfuric acid H2SO4 and vanillin vanilla Used in Russula and Panaeolus identification References edit Ammirati J Traquair JA Horgen PA 1985 Poisonous Mushrooms of Canada Fitzhenry amp Whiteside in cooperation with Agriculture Canada p 40 ISBN 978 0 88902 977 4 Beuhler M Lee DC Gerkin R 2004 The Meixner test in the detection of alpha amanitin and false positive reactions caused by psilocin and 5 substituted tryptamines Annals of Emergency Medicine 44 2 114 20 doi 10 1016 j annemergmed 2004 03 017 PMID 15278082 Kileci Ksoll R Winklhoer C Steglich W 2010 Synthesis of schaefferals A and B unusual phenylhydrazine derivatives from mushrooms of the genus Agaricus Synthesis 2010 13 2287 91 doi 10 1055 s 0029 1218790 a b Hui Y H Smith R A Spoerke Jr David G 2000 Foodborne Disease Handbook Second Edition Volume 3 Plant Toxicants CRC Press p 745 ISBN 978 0824703431 a b Spoerke David G Rumack Barry H 1994 Handbook of Mushroom Poisoning Diagnosis and Treatment CRC Press p 146 ISBN 978 0849301940 Bresinsky A Besl H 1990 A Colour Atlas Of Poisonous Fungi A Handbook for Pharmacists Doctors and Biologists CRC Press ISBN 978 0723415763 Kerrigan Richard 2016 Agaricus of North America NYBG Press p 45 ISBN 978 0 89327 536 5 Arora David Mushrooms Demystified 2nd Edition Ten Speed Press Berkeley 1986 Jordan Michael The Encyclopedia of Fungi of Britain and Europe Frances Lincoln 2004 Kuo Michael 100 Edible Mushrooms University of Michigan Press Ann Arbor 2007 Largent David L Baroni Timothy J How to Identify Mushrooms to Genus VI Modern Genera Mad River Press 1988External links editMushroomExpert com Retrieved from https en wikipedia org w index php title Chemical tests in mushroom identification amp oldid 1195293647, wikipedia, wiki, book, books, library,

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