I recently found some mushrooms from last year in my rucksack.

I usually take better care of fungi. But I figured waste not, want not.

I learned i'd be home alone a few weekends later. So I marked the calendar and began looking forward to my first solo trip in a while.

Saturday arrived. Here we go! I made breakfast then fasted for the rest of the day. As the sun set I clarified my intentions, queued up a playlist, arranged a comfy nest for myself and... nothing.

A heroic dose turned out to be a microdose.

Still, I had a lovely time. A much better time than my friend who just lost a whole batch of freshly grown mushrooms to mold.

After these mishaps I became curious about how best to dry and store mushrooms to ward off:

• decomposition by microorganisms

• loss of potency

In the past i've followed all the standard advice (except the rucksack incident).

But on review I noticed most sources don't explain the underlying logic. And if they do, they focus on decomposition while ignoring loss of potency.

So I went deeper.

What do we really know about how mushrooms degrade over time during drying and storage?

And how can we use this information to maximise shelf life and potency?

Fighting decomposition

For shelf life, everyone agrees that moisture is enemy number one.

This is because decomposer microorganisms like bacteria and fungi need moisture to grow.

In my friend's case this growth was obvious enough to steer clear. But signs of contamination can be more subtle and lead to food poisoning if consumed.

Understanding loss of potency

For potency, I found it more difficult to work out what we're fighting against.

There's a prevailing assumption that loss of potency is also somehow linked to moisture. But it's rare to find any justification for this.

The exception is in forums where enthusiasts have debated the topic for decades. To a chemistry layman like myself, many of their ideas sound plausible. But they haven't been put to the test as it turns out it's difficult to study the best way to handle illegal drugs…

Fortunately, in recent years, studies are starting to shed light on how mushrooms lose potency over time.

It appears to be a two-step process (see here and here for more information).

Step 1: Psilocybin to psilocin

Enzymes in the mushroom convert psilocybin to psilocin. This process is called dephosporylation and requires water. Enzyme activity in general is also dependent on water.

In a fresh mushroom, these enzymes are stored separately from psilocybin. But drying breaks down cell walls and allows them to come into contact.

This step wouldn't be a problem in isolation. It is actually psilocin – not psilocybin – that is psychoactive as it can cross the blood-brain barrier due to its high lipid solubility. Enzymes in our intestine and liver perform the same conversion when we consume psilocybin.

The problem is that psilocin is unstable.

Step 2: Oxidation of psilocin

Psilocin breaks down into various non-psychoactive compounds through oxidation.

Oxidation of psilocin is catalysed by enzymes in the mushroom. It produces blue compounds responsible for distinctive bruising of psilocybin-containing mushrooms. Psilocin will still break down in air in the absence of enzymes but at a slower rate (and into non-blue compounds).

It's sad enough that we're losing psilocybin and psilocin. But the oxidation of psilocin produces water. So we have a vicious cycle. A dry mushroom – which will still be 5+% water – can slowly regain moisture even in dry air.

Finally, all of these reactions are accelerated by light and heat.

How To Dry And Store Mushrooms

How can we use this information to dry and store mushrooms in ways that maximise the shelf life and potency?

Drying

You should get mushrooms as dry as possible to:

• slow the growth of decomposer microorganisms

• slow the activity of enzymes that break down psilocybin and psilocin

You should test that they are "cracker dry" meaning they snap without bending. This applies even if you're starting out with dried and not fresh mushrooms.

If in doubt, dry them out.

Option 1: Food dehydrator

Your best bet is a food dehydrator which will set you back about £40 (although a freeze drier would be preferable if you have a spare £4,000).

A dehydrator efficiently removes moisture from food by:

• gently heating it to draw moisture out to the surface

• circulating air to encourage evaporation of this moisture

• pushing moist air out through vents so it isn't reabsorbed

A typical dehydrator has a temperature range of around 35C to 70C. What should you set it at?

A high temperature will dry the mushrooms more quickly. A sufficiently high temperature would denature enzymes and prevent enzyme-driven degradation in storage.

But higher temperatures will also speed up degradation reactions while the mushrooms are not yet sufficiently dry.

We don't yet know which of these factors is more important. I even resorted to combing through patents held by biotech companies for extracting psilocybin from mushrooms:

So, for now, the choice of temperature is up to you. Drying will take around 12-24 hours and you should also limit exposure to light during this time.

Option 2: Air dry with fan

If you don't want to buy a dehydrator, an alternative is to place mushrooms on a wire rack and point a fan at them.

But – for a given temperature – this will take longer than a dehydrator and so would lead to more loss of potency.

Option 3: Fan oven

If you have a fan oven, you could also place mushrooms on a wire rack at a low temperature. Leave the door cracked to allow moist air to escape.

This is a crude and very energy-inefficient version of a dehydrator.

Storage

Now that you've got your mushrooms dry, you need to keep them dry.

You also want to limit oxygen exposure to prevent the oxidation of psilocin. But this is a secondary concern to limiting moisture which will limit the breakdown of psilocybin to psilocin in the first place.

For long-term storage, you should store mushrooms in whole rather than powder form. Grinding will speed up degradation by:

• increasing cellular disruption and freeing more enzymes

• increasing surface area for oxidation

It can be convenient to pre-grind mushrooms if you are microdosing. But experiments suggest you should not do this more than a week ahead as ground mushrooms can almost halve in potency within one month.

Option 1: Vacuum pack

If you have a vacuum sealer, then the best way to limit exposure to both water and oxygen is to store mushrooms in vacuum-sealed pouches.

Option 2: Airtight container with dessicant pack

A simple but effective alternative to vacuum sealing is to store mushrooms in an airtight container with a dessicant pack.

A dessicant pack will absorb water from the air as well as water produced by the oxidation of psilocin. Mushrooms stored with a dessicant pack have been shown to have 30% higher psilocybin content on average.

Dessicant packs are cheap and will usually come with a replacement indicator. You’ll need to replace the pack more often if your container is poorly sealed or you open it a lot.

You might be tempted to add an oxygen absorber to the container. But these need moisture to work and so dessicant packs will render them useless. If you can stay on top of moisture, then oxidation is a secondary concern.

It’s best to store your container in the dark and at room temperature.

All the best for the week ahead,

Nick