Archive for June, 2015

Amanita muscaria – just for the hell of it

nibble

This mushroom needs no introduction, although most people in Western Australia will not have encountered it in the wild.   In fact, the first confirmed occurrence of this mushroom in WA was only comparatively recently in 2009.  See First record of Amanita muscaria in Western Australia.

That paper expresses some concern about this spreading to pine plantations in WA, where I in fact first encountered it.  Unlike the situation in other states, this fungus was not purposely introduced into pine plantations.   It has been demonstrated to be capable of transferring to many of our native trees in SW WA under laboratory conditions, which is of some concern to mycologists it seems. Since the initial sighting, it has been recorded in many places from Perth to Augusta.


Note: May 2016

I am watching this spread through the pine forest where I first encountered it and I have found it invading one section of the pines in the local arboretum.  It is apparently common around Margaret River

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I have known for some time that this mushroom was edible if treated appropriately, so with some specimens in my hand, I decided to research the topic.   My research yielded a paper by Rubel and Arora.

They point out the wide cultural bias against eating this mushroom and point out that the toxic components are water soluble.  They suggest a technique of boiling the thinly sliced mushroom in a saline solution for 15 minutes.

In contrast to that paper, Debbie Viess has published several papers that vehemently oppose the concept of eating this mushroom, though by her own admission, she has tried it.

After reading what was available, it seemed to me that the Viess papers really served to reinforce the cultural bias suggested by Rubel and Arora.  The suggested boiling regime did not seem overly complex as suggested by Viess, and discarding the water didn’t seem like too much of a burden.  So I decided to conduct my own investigation.

Erring on the side of caution, I cut up a single cap into slices of 3 to 4 mm thickness and boiled them for 15 minutes in salted water.  I then drained them and repeated the procedure, finally rinsing the slices in cold water.   After this treatment, there was no red colour remaining, and the slices were of limp, unappealing appearance.  However, I fried them up in a little butter/oil mix until they were slightly brown and found them to be quite tasty.

What troubled me was the lack of actual data regarding the rate of removal of the toxins, so I decided to do my own investigation.   It seemed to me that if the toxins are readily water soluble, then one might expect to see some change in the conductivity of the extraction solution.   So I sliced up a single cap, weighing 45g and placed it in 1 litre of water.   The conductivity immediately rose from 31 microSiemens to 60 microSiemens. I then began to heat the combination until it boiled and maintained it at a steady boil for 3o minutes, allowing it to rest for a further 30 minutes.   During this procedure, I took 10 ml samples with a plastic syringe and added them to 100ml of cold water, measuring the conductivity of the resultant solution.  From this  I could calculate the conductivity of the hot water solution.  I repeated this exercise with another cap of 40g weight which I pulverised with a blender for 2 minutes.  My results are shown below.

graph

The blue line shows the conductivity of the solution for the case of sliced caps and the red line shows the result for the pulverised caps.  The higher starting point for the pulverised caps shows that the finer particle size provided more rapid leaching.  This indicates that diffusion of the soluble components from the mushroom mass is rate controlling.  Hence the need for thin slicing and boiling.

I had no means of determining the actual amount of soluble toxin in the solution, but since these toxins are highly soluble, I expect that they would follow the trend with the total soluble components.  It would seem that a photometric measurement in the deep ultraviolet region at 254nm would be needed to follow the amount of ibotenic acid and muscimol in the solution.

I should note that I have not taken into account the lowering of the volume of the boiling water during the extraction process.   Because of this, my readings are higher than they should be.  Despite this, they do show that there is a fairly rapid increase in extraction in the first 15 minutes followed by a reduction in the extraction rate.

From my point of view it would be preferable for someone better equipped than myself to conduct experiments along these lines and to publish the results than to go to the extraordinary lengths that Ms. Viess has gone to in the way propagating fear of the unknown. In any case, I can report that I have consumed about 10 grams of the boiled slices without any ill effect whatever.

I wonder how the kangaroo that took the nibble out the specimen pictured above is feeling?

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PS  There is a description of what happened to some people who only boiled the mushrooms for 3 minutes at this link.

Prue in Tasmania reports pickling these. She has given a link below.

Debbie Viess has taken the time to add a comment below as well.

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Agaricus osecanus – Giant horse mushroom, giant disappointment

cropped giant horse

I found this monster growing at the base of a eucalyptus tree in Bridgetown.  It was almost buried, rather like Agaricus bitorquis.  Although I have called it Agaricus osecanus, that is a fairly loose term, referring to a group of similar mushrooms. I am using Arora as a guide.

I first found these during Spring, and then again in Autumn.  The most distinctive feature of them is the huge diameter of the stem.   As you can see, it is a handful.   In fact the specimen above appears to be three individuals fused together and it had dried out a little and cracked so that it was in danger of falling apart.   The flesh however was quite firm.

I was quite excited when I found such a large mushroom that was clearly an Agaricus of some sort and therefore likely to be edible.   I thought that I would take a culture of it as soon as a I could.   However, the smell was not like any other member of the genus that I have ever encountered.   A friend described it as ‘earthy’ but I found it simply ‘less than attractive’.

Before going to the trouble of culturing it, I decided to do a small taste test.  To this end, I cut some small slices (no colour change) and fried them in a little butter/oil.   My friend and I both tasted it and though the initial taste seemed ok, we had both spat it out within 5 seconds.   It tasted terrible.  Hard to describe exactly, but I found it to have a floury taste.  Certainly not something that you would want to swallow.

So, for me this represents a fourth grouping within Agaricus, based mainly on the smell.  The other three categories are mushroom (octenol) smell, almond smell and phenol smell.  I can’t put a description to this smell, but it does not fit into any of the other three categories.   `

Such a shame.  It was massive and had lovely white firm flesh.

Ah well.

Note: May 2016

I had hoped to get another specimen of this and send it off for dna testing, but this year someone came along and not only smashed them up, but ripped off all the loose bark of the tree whose base it was growing at.  Such a senseless act and now we may never know what this was.

 

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