Notes: The almost instant dark bluing is characteristic. The bluing reaction of Gyroporus cyanescens is not caused by oxidation of variegatic acid, which is responsible for the bluing of many Boletus species, (as has sometimes been assumed), but by oxidation of gyrocyanin, which is a more highly oxidized bis-phenol-substituted cyclopentenone. The chemical structure is shown in one of the pictures.
[admin – Sat Aug 14 02:01:34 +0000 2010]: Changed location name from ‘Jamieson Park, Poynette, Columbia Co. WI, USA’ to ‘Jamieson Park, Poynette, Wisconsin, USA’
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Does the color go away when you cook it?
Yes, compounds from which hydrogen is very easily abstracted, like diphenols (variegatic acid and gyrocyanin are both diphenols), are antioxidants. Phenol (hydroxybenzene) itself is quite poisonous, and acidic enough that it causes burns if you get it on your skin. (the old name for phenol was carbolic acid). However, substitution of electron-releasing alkyl groups on the ring lowers the acidity enough that substituted phenols no longer burn you. The natural phenolic antioxidant is vitamin E, which is an ortho diphenol. Artificial Vitamin E does not have the stereochemistry at the methyl groups in the side chain controlled, but is still sold as Vitamin E. A famous chemist named Kieth Ingold, who works at the National Research Council in Ottawa, Canada, tried to get somebody interested in studying the possible effects of having these other diastereomers present in artificial Vitamin E when he discovered that Vitamin E sticks around in rat brains longer than the life of a rat, but failed to get this research funded. The phenolic antioxidants that are approved to be put into food by the Food and Drug Administration are BHT and BHA. BHA is a mixture of two compounds because the reaction that produces it makes two compounds, neither of which hurts you.
When people say that a compound is an antioxidant, what they mean is that it inhibits free radical chain reactions. Such reactions are involved in “aging”. It is free radical induced “autoxidation” (oxidation that starts without any catalyst) of the unsaturated fatty acid derivatives (fats) in food that causes spoilage of it. That is why you can hardly buy anything in the store that is not expected to last more than a couple of days that does not have BHT or BHA in it. I have added a picture that has chemical structures of the compounds mentioned here.
Variegatic acid is hard to say? I was telling one of my friends about it on the phone earlier, i said it:
Keys to Agarics and Boleti that tells about the color reaction components, variegatic acid easier spelled then said
I get the same question, and have spent hours looking for the answer online on numerous occasions… I wasn’t even sure if the chemical(s) to cause bluing in boletes was known.
Thanks so much!
People always ask me what is the blueing agent in our western boletes,
and now I’ll be able to say “variegatic acid, of course”…
Created: 2010-06-28 11:38:50 PDT (-0700)
Last modified: 2010-08-26 18:19:11 PDT (-0700)
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