Fermented Mushrooms – Triple Threat of Flavor Enhancing

Ok so I don’t necessarily want this to become all fermenting all the time but but it’s what I’ve been playing with and believe me now that we’re all moved and settling back into life I have a lot of goofy things I want to try. Like last week’s post I tried the lacto-fermentation technique for mushrooms and with a slight variation the results have become another workhorse of my kitchen.

If you have the Noma Guide to Fermentation you’ll recognize this technique. If not, get ready for lacto-fermenting 101. Lactobacillus is a common bacteria which turns sugars into lactic acid, which preserves and protects from bad bacteria as well as changing the flavors and structures of food. Cabbage to sauerkraut for example. For some of the most basic ferments you really just need the right amount of salt. The Noma book is a good ‘next steps’ resource if you’ve been trying out fermentation, had success, and want to do some other things. Back to the ‘shrooms.

This is soooooo simple and easy. Seriously, you can’t mess this up. No really. Mushrooms plus salt (2% weight of the mushrooms), sealed in a jar with weights (or vacuum sealed in a bag) for a week, left on your counter or in a fermenting chamber (Styrofoam cooler with a seed mat). After a week you have a bag full of kinda pickled salty mushrooms a ridiculously funky liquid. It’s the best way I can describe it. Think stinky cheese FUNKY. And the funk changes depending on the type of mushroom you use. I’ve done this with oyster mushrooms (bleu cheese funky) and shiitakes (sharp, acidy, tangy). Oyster mushrooms give off more liquid in my opinion, but I like the shiitakes more for a paste made from the remnants…just keep reading. 

According to the Noma book, the fermented mushroom juice is what you desire (they really like using the extracted liquids from things) and the leftover mushrooms don’t seem to factor in much. You don’t get a lot of juice, maybe a cup from a pound of mushrooms, and it is quite flavorful. But once drained off you’ve still got this bag of mushrooms. What to do. Me being me I took the leftover soft and salty ‘shrooms and tasted. Funky umami but not as strong as the juice. Which really isn’t saying much since the juice is REALLY strong. So what to do with the ‘waste’? 

Throw it in the food processor and puree the hell out of em. Makes a very good umami paste which can be frozen in small cups. There’s more you can do with the paste, but I’ll get to it later. Keep going.

The pureed ‘waste’ is a FLAVOR BOMB. Note the emphasis. Hopefully it gets my point across. If there’s just one thing you maybe might think about trying from this blog to make your cooking better, this is the one. That’s nice, you say, but what do you do with it?

Want to add some depth to a soup or stew? Throw in a couple spoonfuls. Want to add some acidy salty sour umami to potato or egg salad? Spoonful. Got a sauce which needs just that little something…you guessed it, spoonful. Bland Bolognese? Yup. Duxelles? Dux-cellent. And OMG your Robuchon-level-butter mashed potatoes will be elevated to such a height that you’ll never ever ever go back. Trust me.

Ah wait, we’re not done yet. Got a food dehydrator? Oh good. Then smear some of the pureed mushrooms out on parchment paper and throw it in the dehydrator (I did 150F for 6hrs, which is probably excessive but it achieved the results I wanted). Um yeah. The paste turns into a brittle cellophane looking sheet which I put into a mortar and pestle and ground for a fermented mushroom powder. A salty, funky, mushroomy powder. I’ not quite sure what to do with this yet but it seems like a good candidate for sprinkling on things, deviled eggs, salads, etc.

I would highly recommend getting the really good farmers market mushrooms for this. It works for any of them but hey, better quality better end product (Noma says button mushrooms don’t work so well, shiitake and oyster are best). One thing to note, no two ferments come out the same. They’ll be similar but things will change depending on the batch of mushrooms, like color of the juice and paste. Note how light brown the juice and paste are in the photos. I’ve had batches much darker brown and much much lighter. Flavors can be more intense or funky as well. Doesn’t matter, the umami is still there.

There’s your mushroom ferment trifecta. I take it up a level, then another, then another. Just like Inception, there’s layers within layers of flavor going on in the test kitchen!

[Side Roam: With the exception of the freezing part the following steps can be used to lacto-ferment a lot of things like fruits and vegetables. For example, blueberries. Lacto blueberries come out salty and sweet and are an excellent addition to your morning granola & yogurt, blueberry muffins or bread, mashed up and reduced with honey into a sauce or glaze. If you do this mushroom ferment do blueberries next and leave them whole. They freeze well in small batches too.]

Lacto-fermented Mushrooms

  • 500 gr mushrooms
  • 10gr kosher salt (or 2% of the weight of the mushrooms)

Freeze the mushrooms overnight. This is supposed to help break down some cell walls and aid the process.

Add the salt to the frozen mushrooms and toss together in a bowl. 

Put the mushrooms into a vacuum bag or if you have fermentation weights you can use a jar. You can also use a ziploc bag and squeeze out the air.

Seal up the bag/jar and let it sit for a week or 10 days. It’s fine on the counter but if you’ve made a fermentation chamber then put it in there set for 80F.

According to the Noma book you should ‘burp’ the bag/jar occasionally but I’ve never experienced a build-up of gas large enough to necessitate this. It’s easy with a jar, just open it then put lid back on.

After a week or so, strain the mushrooms through some cheescloth and collect the juice. Squeeze the shrooms to get more liquid out.

Take the liquid and freeze.

Puree the mushrooms and store in a container. I like to divide up into smaller containers since you don’t really need much of this and having 12oz of it in the fridge will take a while to get through. Can freeze in ice cube tray and then put in a bag.

Liquid all frozen? Good now take that out and put the block in some cheesecloth and place it on a small strainer over a bowl in the back of the fridge. It’ll melt over the course of a couple days leaving behind solids but giving you all the liquid. Good stuff.

For the powder, if you have a dehydrator spread out a layer of the paste, dehydrate then grind into a powder.



  1. chef mimi says:

    Fascinating. I have a ton of dried mushrooms, cause I love making mushroom powder. How could they be used for fermentation?

    1. I don’t think dried would work with this. I have always just used fresh ones. Dried might work for a miso or garum, those are next up in the test kitchen!

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