Archive for April, 2010

Boletes – a lost resource

“Few orders of plants appear to contribute more to the support of animal life in Western Australia.  Many species, Particularly, the genus Boletus, are used as food by the natives and directly supply no inconsiderable portion of their support for several months a year.”

James Drummond, the pioneer botanist of WA.

This quote is from an article by eminent mycologist Roger Hilton, in a short article about edible fungi he wrote in the journal Landscope in 1988.

In Western Australia there is a large number of boletes that spring up each Autumn.  Judging from overseas experience, it is likely that a lot of these are edible species, but all of the knowledge of Aboriginal consumption of these fungi sadly has been lost.

Hilton comments there are boletes that will make you sick, but none that are known to be lethal like the Amanitas.   However, there has been one recorded case of a fatality from eating a bolete.  In this case it was from muscarine in the mushroom. 

From time to time, I experiment with some of the many boletes that spring up on my property.  My standard test is to lightly fry a few small slices in some oil and do a taste test.   By this means, I have been able to eliminate a few as being too revolting to consider.   There remain others that are tantalisingly tasty.  I tried one a few hours ago.   It was a handsome specimen with firm white flesh and a black cap.   When cooked in this way, it produced a wonderful tasting type of crisp.  So far, I am feeling no ill effects from the very small pieces that I tasted.   But this is not for the faint-hearted!   Over the years, by cautious exploration, I hope to be able to find one or two boletes that are edible.  I would rather be using a gas chromatograph for the initial assessments, however.

Presently, the only boletes that are known to be edible are the Slippery Jacks and Phlebopus marginatus, the Salmon Gum mushroom which often appears in the news because of it’s giant size.

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Biochar – an experiment

Each year as the wet weather sets in, there is a narrow window where it is possible to burn off the accumulated branches from the preceding year, to keep the ground clear and mitigate against bushfires.   This year, one pile was made with a lot of sand in it.  And it rained soon after it was lit.  So the result was a pile of charcoal under a crust of wet ash, that continued to burn slowly.

In this situation, the charcoal is formed under a condition of low oxygen potential.  This situation should provide for a high surface area charcoal and it bears some similarity to the environment 0f the pit kilns that appear to have been responsible for the pottery chard-filled biochar of antiquity.

In the meantime, I had built two above-ground garden beds that I had filled with horse manure/hay.  After a few days, these beds were beginning to show weed seed germination and one was infested with fly larvae.  The beds had been boosted in phosphorous by the application of blood and bone, but there was no source of potassium in the mix.

So I decided to combine the two problems.  My thoughts were that the hot charcoal/ash mix would kill the fly larvae and the surface weed seeds as well as providing some potash for the mix. 

I headed off for the fire heap in the tractor.  Splutter, splutter.  Oh no, ran out of diesel.  Added diesel but the battery ran flat without a start.  Took out the battery and have it on charge.  Fingers crossed that I will not have to bleed the fuel system.

So, I grabbed the wheel barrow, headed for the pile and the dead tractor and starting filling the barrow with hot charcoal.

I then wheeled the barrow up to the raised garden beds, which were made from rings cut from an old water tank, and added the hot charcoal to the top of the beds.  I did a few loads like this.  Then I dug the hot material into the top of the horse manure for a depth of about 200 mm.   This produced a lot of steam and in effect sterilized the top layer of the beds.

My intention is to plant potatoes into the bed shown above.  I will put a layer of sand in first and will top it up as the plants grow  with further sand, as sand is freely available here.   Last year, I used sawdust, and all my potatoes turned yellow and died!  So, no more sawdust.

Before I plant anything, I will water the beds well though, as the initial watering will produce a very high pH liquid, potassium carbonate, that will need to be neutralised by the natural acids in the manure before the beds can be planted.   That high pH liquid will be a further source of sterlisation for the horse manure.

Update, November 2010

The potato plants have all died off and I have begun to harvest them. They are all beautifully clean as they come out of the sand and just need a light wash to clean them up for cooking.

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Coprinus comatus – The shaggy ink cap

This mushroom is not a native, but it grows in Australia.  It is often found in parks and on waste ground and once established in a patch of ground, they will come up year after year.  Often, they favour grassed areas where the grass clippings are allowed to rot down in situ.  The one below is on the edge of the local football oval where it comes up each year with the onset of the first rains and continues to fruit through winter.

These mushrooms, in common with all the members of the genus, self-decompose into a black inky mess.   The one above is beginning to go through that process and the one below is well into it.

For culinary purposes, the mushrooms need to be picked before the decomposition process has set in.  Decomposing specimens need to be kept apart from fresh ones.   They can be kept in iced water in the fridge for about half a day to avoid onset of the decomposition reaction.

For years I tried to incorporate these mushrooms into dishes without much success.  They always turned into a horrible slimy mess.  Then someone explained the trick.  You need to slice them and then toss them in a pan for a while on low heat until they have lost a good proportion of their moisture.  After that, they can be cooked as you would a normal mushroom.  The de-watering step ensures that they remain firm during the cooking process.

It is also possible to dry these mushrooms if you happen to have a dryer, or if the weather is sunny.  Drying must be done to the point of crispness.  Once dried, they can be used to impart a distinctive flavour to dishes.

Many books declare that this mushroom cannot be eaten with alcohol.  Unfortunately, this is a myth that has been propagated throughout the world.  Some of the confusion is due to the fact that the mushrooms that do cause this problem used to be grouped in the same genus, Coprinus.   With the advent of DNA profiling, things have been changed around and there are now only a few species left in the genus Coprinus.   The offending mushrooms are now in the genus Coprinopsis.  The most well known member of the genus that causes problems with alcohol is Coprinopsis atramentaria, the common ink cap.   It is notable that Coprinopsis and Coprinus are not only different genera, but they are in different families.   Coprinus is in Agaricaceae and Coprinopsis is in Psathyrellacea.  They are not even closely related!

The compound that causes the issues with alcohol is known as Coprine.   It is an unusual amino acid.  There are other unusual amino acids in other fungi that are also responsible for toxic effects.    The structure and breakdown reaction of coprine are shown below.

 

 

coprine mechanism

When we consume alcohol, our body processes it in a specific way.   It is first converted to acetaldehyde and then that is acted on by an enzyme called aldehyde dehydrogenase which converts the acetaldehyde to acetic acid.   The aminocyclopropanol in the reaction above blocks the action of aldehyde dehydrogenase and the result is an accumulation of acetaldehyde in the body.   This is toxic and it gives a reaction similar to Antabuse, a drug that has been used to treat alcoholism.
There is no truth in the idea that coprine itself has been used to treat alcoholism.  It has far to many other toxic side effects to be used clinically.   One of those side effects is to cause tumours in the reproductive system of males.

 

Coprinus comatus is a relatively large mushroom.  It can attain a height of 200 mm or more and is typically 20 to 30 mm in diameter.   It should not be confused with some of the similar looking small species that are sometimes seen on composts for example.  One mushroom of similar stature that occurs in my part of the world is Coprinopsis aff. stangliana.   It is shown in the image below kindly provided by Luke Cashmore.

Coprinopsis aff. stangliana

Coprinopsis aff. stangliana

 

 

 

 

Footnote May 2011. I found a large patch of these growing nearby a few days ago and picked several kilograms of them. In order to handle them quickly, I decided to chop them and render them down to a soup in a stainless steel pot. It was an expensive pot with a copper insert in the base and I bought it for making jam. They rendered down nicely and I left the pot on the stove overnight, then decanted it into two smaller containers in the morning. The resultant mix had a pleasant, almost sweet smell. However, upon tasting a small sample of soup made from the mix, my senses were soon overcome by an unpleasant metallic taste. Research suggests that this is 1-octene-3-one. I can still taste it after 24 hours and two intervening meals. I have never tasted anything with such a persistant after taste. So that is something to be wary of with this mushroom. I have dried a smaller sample of them, and will investigate their taste with caution.

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Agrocybe (Cyclocybe) parasitica

At the top of my list of edible mushrooms that I have not tried is Agrocybe parasitica.  That is because it is a large mushroom and can occur in fairly large clusters.  It should also be possible to cultivate this mushroom.

 

Above picture is courtesy of Reiner

Various sources disagree with respect to the edibility of this mushroom.  None list it as poisonous, but some advise caution.  On the other hand, Watling and Taylor (1987) describe it as an excellent edible.  Their description can be found here.

9 May 2021

It is 11 years since I made that post. This year has seen a flurry of fb posts from people in northern NSW describing this as the best tasting mushroom that they have ever eaten. It seems that it occurs in quite large outcrops in that area as well as in New Zealand. It also occurs in Tasmania. I am still to taste it. Oh, and it has had a name change to Cyclocybe parasitica.

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