[Nhcoll-l] Freeze-drying of mushrooms

[Alejandra]

Dear friends,

First time here, thanks for accepting me!

I am biologist working for a village in Andalucía (Spain) where they want
to create a mycological museum. I've been collecting mushrooms for a month
and freezing them (in a normal freezer). Then, I've made six attemps to
freeze-dry some specimens -using a freeze-dryer (photo attached)- but
somehow I don't success yet. I couldn't find any protocol for*
freeze-drying fungi* online, and was wondering if here anyone has worked
with it o anything similar.

I have doubts regarding freeze-drying in itself but also the preservion of
the specimens afterwards. So, these are the parameters and times I've been
trying and some of my doubts:

- I *freeze *the mushrooms for about 4-6h at -50ºC, and then I've been
trying different *sublimation *times (I aim to achieve 0.1mbar but the
machine doesn't go below 0.4mbar): I tried half a dar, one day, two days,
three days... For small mushrooms such as *Marasmius *or *Tricholoma, *three
days seem enough. For bigger mushrooms such as *Lactarius* or *Lepista*, I
think at least four. For somehting like a big *Boletus* I don't even know.
Any suggestions?

- I've been doing two things which I don't know if they are
counterproductive. I've made small *holes *in the widests parts of the
mushrooms with a needle, hoping that by doing them mushrooms will freeze
better and freeze-dry faster. Moreover, I've been doing *cycles *of
freezing-sublimating, i.e. freeze 5h, sublimate 24h, freeze other 3h,
sublimate 24h.... Maybe braaking the vacuum and creating water crystals
again is not intelligent... Any idea if this makes sense?

- The freeze-dryer has the option of applying *heat*. Would be a good idea
to apply some heat after the sublimation so as to make sure all humidity
goes away? How much and for how long?

- Okay, now with the "aftercare". The only time I achieved positive results
(mushrooms were beautiful and dry), I took the mushrooms home without much
protection and put them inside a plastic box and closed it. A few days
later I opened it and found them to be soft and damaged by moisture. Next
time after taking them out of the freeze-dryer I will inmediately put them
on the box but filled with *silica gel*. Then, when remaining humidity is
absorbed, I would like to cover the mushrooms with some kind of *barnish*.
I have an* acrylical spray* one, but was also wondering other options (that
do not change too much the color or texture, that preserves the specimens
agains humidity and insects, and that make them a bit resistant and
tougher). Any opinions about any of this?

Thank you a lot for taking the time to read and consider my situation :)
Any suggestion or resource is deeply welcomed.

Wish you a good day,

Alejandra

[image: IMG_5507.jpg]


[image: FA86D3C6-A7D8-49AF-82C7-C7DA95534B0D.JPG]
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