Mushrooms are one of my favorite foods. They go with almost everything and they enhance so many wonderful flavors! Unfortunately, not everyone in my family likes the texture of mushrooms, so I’ve turned to freeze-drying them – so we can still have the taste! But how do you freeze-dry mushrooms?
Freeze-drying mushrooms involve steps like preparation, pre-freezing, freeze-drying, evaluation, storage, and reconstitution. Tips like slicing raw mushrooms before freeze-drying, crushing them afterward, and only reconstituting them while cooking makes them even better.
Ready to get all of the steps and tips? There’s 12 in total – but knowing these makes a huge difference in the final dish. So make sure you read them all!
How to Freeze Dry Mushrooms in 5 Simple Steps
Ready to freeze-dry some mushrooms? Here are the basic steps.
- Prepare your mushrooms for freeze-drying.
- Freeze the mushrooms and prepare your freeze dryer for use.
- Freeze-dry your mushrooms.
- Once done, evaluate the mushrooms for dryness.
- Package your mushrooms for long-term storage and use.
Now, that’s really it when it comes to freeze-drying pretty much anything. This is the same set of steps for freeze-drying bell peppers (though if you want the secrets to delicious freeze-dried bell peppers, I do recommend you read the extra tips and steps!), broccoli, steaks, and anything else you could ever want to freeze dry.
But here’s the thing – these basic steps do better when you have the accompanying tips. So, let’s not just go into the basics. Let’s dive into the tips and tricks to help you master freeze-drying mushrooms!
Wash, Dry, and Cut the Mushrooms
Prepping the mushrooms for freeze-drying will largely depend on your own personal preference and food hygiene habits. But washing them should be the first step. That way, you aren’t worried about any dirt or germs in your food.
Now, if you’re growing and harvesting your own mushrooms, then the amount of washing you do may be different than if this was a bunch of mushrooms you bought on sale at the store. But in either case, washing the mushrooms will help.
Once washed, let those mushrooms dry. You can air dry them or pay them dry with a towel. I like to set my washed mushrooms on a towel, gently pat off some of the water, and then I’ll let them air dry for a few minutes. I’ve found that trying to towel-dry mushrooms too vigorously leads to squashed mushrooms – and that makes slicing them harder! Using a salad spinner (if you have one) might be a great option.
Now that your mushrooms are clean and dry, it’s time to cut them up. The more surface space you expose on the mushroom, the easier and faster they’ll freeze-dry. I’ve found that sliced mushrooms freeze-dry best. However, they can be pretty thick slices and still freeze-dry well.
We’ll talk more about how to cut them up later on in this article, though if you’d rather cut them in any of these other manners, it should still work well.
- Sliced (this works best, in my experience.)
- Minced (although this one is overkill with freeze-drying – it’s far easier to do sliced mushrooms, freeze-dry them, and then powder the mushrooms after they’ve been dried. You get the same end result with a lot less work.)
Now, sometimes it may be easier to wash, cut, and then dry. That works, too. It’s a personal preference – and it still gets the job done while getting us to the next step.
Pre-Freeze the Mushrooms and Prep the Freeze-Dryer
Pre-freezing is a hugely important step. It makes freeze-drying so much easier. Here are the two easiest ways to pre-freeze mushrooms for the freeze dryer.
- Load a freeze-dryer-sized tray with mushrooms. Mushrooms freeze well this way, although they may clump depending on how full you loaded the tray. However, mushrooms still process really well even if they’re all clumped up.
- Load up a cookie sheet (the half-sized sheet pans) with mushrooms. Ideally, leave enough space between the mushroom pieces so that everything freezes into separate pieces. Then, once frozen, the pieces can be moved onto the freeze-dryer-sized trays for immediate freeze-drying or into a plastic bag for storage until the freeze dryer is available.
We’ve used both methods with success. And, honestly, which I use depends largely on how much room I’ve got in the freezer – and how many mushrooms I’ve got to freeze dry. It also depends on my final goals with the mushrooms.
- If you’re going to use mushrooms primarily for flavor (and the final shape isn’t vital), it won’t matter which option you pick. Some clumping of frozen mushrooms won’t matter.
- If you’re wanting to have separate, identifiable pieces of mushrooms in your food storage, then you’ll need to pre-freeze them separately no matter what size of a tray you use.
Now, while your mushrooms are busy freezing, it’s time to go prep your freeze dryer. You’re going to want to start it before you add the food (or the food trays). This way, the interior of your freeze dryer is completely frozen and ready to go.
- We have an older machine with older software, so we use below -80 degrees Fahrenheit as our “the freeze-dryer is ready to go with our pre-frozen foods!” point. That’s just the point we use, though any point below your freezer’s usual storage temperature could work, too.
- For newer machines with newer software, you won’t need to get your unit that cold – you could probably get away with -25 degrees or even the standard settings.
- The reason to get machines this cold is more important with items that are sugary (like fruits) or high in salt, so if you don’t salt your mushrooms then the super-low temperature isn’t as vital.
This step is important for a few reasons, but we’ll talk about them later on in this article. For now, know it’s important.
Freeze-Dry the Mushrooms
Once your mushrooms are frozen and the freeze dryer has been going for a few hours in its first freezing cycle, you’re finally ready to freeze dry your mushrooms.
If you haven’t already, go ahead and transfer your mushrooms to the freeze-dryer-sized trays. Next, load those trays into the freeze dryer.
Next, go ahead and make sure that you’ve got your freeze dryer settings ready to go at an appropriate level per the manual’s instructions.
- If your mushrooms are pre-frozen and thinly sliced, then it takes about a day to freeze-dry them adequately.
- For larger mushrooms or less-dried pieces, then it could take 36-48 hours to achieve a proper freeze-dried state for storage.
Let the freeze dryer do its thing, and check on it periodically. I like to set an alarm on my phone (or on our Alexa) for when it’s due to be done. Then again, I also like to manage our freeze dryer so it’s done during daylight hours because I don’t want to wake up in the middle of the night to put away food. So feel free to adjust the timing of things if you’re like me in that “sleep is awesome!” sort of way.
Oh, and make sure you end your freeze-dryer on a warm cycle (instead of a cold cycle). It’ll make things a ton easier. But don’t worry – I’ll explain why later on in this article!
Check Freeze-Dried Mushrooms for Dryness
Once your freeze-dryer is done on its warm cycle, pull out a tray. Test a few mushrooms for dryness. A properly freeze-dried mushroom should be completely brittle, snap into two without much trouble, and have an amazing snap sound.
Go ahead and check several mushrooms on each tray. If they aren’t totally dry, then go ahead and put them back into the freeze dryer. Set it to go for another few hours, ending on another warming cycle.
If all of the mushrooms tested are completely dry (and pass the snap test), then congratulations! You’re ready to do the secondary dryness test.
Transfer your mushrooms from the freeze dryer (and the trays) into some gallon-sized Ziploc bags (or an off-brand, if that’s more your style). Get as much air out of the plastic bag as possible.
Yes, we’re packing the food into plastic bags. We aren’t using the Mylar bags just yet. That’s the packaging step. We’re still in the “checking for moisture” step. Trust me.
You need to put your freshly freeze-dried food into a plastic bag for storage for a few days. Keep the plastic bag in a cool, dark place – like a pantry. This way, you can see if there’s any moisture (via condensation on the bag) still in the food.
If there is any water, then you know that the food wasn’t actually properly freeze-dried or that the food accumulated too much moisture from the air after being pulled out of the freeze dryer. Either way, that food won’t have a super-long shelf-life. It’ll need to be eaten sooner rather than later.
Or, you may be able to run the food through another freeze-drying cycle. Even if that works, though, know that the total expected shelf-life of that batch of mushrooms will be on the shorter end of things.
On the other hand, if there’s no visible moisture on the bag after a few days, then your food is super dry. And you’ll be able to safely store those mushrooms in a Mylar bag (in the next step) for years. They should be safe to store for the longer end of the food storage spectrum.
Now, here’s the reason we added the plastic bag water check step to the process: we lost a good bit of food to moisture-based spoilage when we skipped this step. Only, because we couldn’t see the moisture through the Mylar bag, we didn’t know it until we opened the food.
And it’s hugely disheartening to see spoiled food when you were expecting something to be still good. Because not only did you lose your dinner plans, you’ve also lost that food – and you’re out the price of the Mylar bags. Mylar bags aren’t cheap!
So don’t do your testing with Mylar bags. Go ahead and do the final moisture check with a plastic bag. They’re far cheaper and can, in some instances, be reused.
Save yourself the heartache – do the extra moisture check. It’s so much nicer knowing for certain that your food storage is safe and properly stored for the long haul.
Package Freeze-Dried Mushrooms for Long-Term Storage
Now that your food has successfully passed the plastic baggy, extra-dryness test, it’s time to put the freeze-dried mushrooms into long-term storage. There are a few ways to do it, so we’ll talk about each briefly.
Mason Jars are a fun, visually appealing way to store freeze-dried foods. They’re a great way to see what you’ve got stored or if you want a cool, visual aesthetic.
The downside to mason jars is the fact that they are more susceptible to light, air, and general degradation. So if you are going to store food in mason jars, it’s best to store them in an area that’s light, temperature, and humidity-controlled. Then, you’ll also want to consider vacuum-sealing them (with an oxygen absorber inside).
Just putting food into a mason jar and calling it good isn’t a viable food storage solution. We tried it – the freeze-dried food (fruit) only lasted a few months at best. And that was if we weren’t opening the jars regularly. Jars that we opened and used as a regular storage space for food shortened the shelf-life to a matter of weeks.
Mylar bags are the best option for the longest-term storage of mushrooms. You don’t have to vacuum seal these. Just add an oxygen absorber and use your impact sealer to close the bag. We like to do two seals on our bags. That way, if one seal fails, the other is a backup.
Then, store the Mylar bags of food in a dry, cool area – like a pantry or a closet. This will help you get the longest, best storage time possible out of your food.
No matter which storage option you pick, make sure you label the packages with their contents and the dates packaged. Playing food storage roulette isn’t super fun – trust me.
Sliced Mushrooms Freeze-Dry Better
Sliced mushrooms freeze-dry better and faster as they expose more surface area to the vacuum to remove water. Whole mushrooms can still freeze-dry, but they will take much longer to properly freeze-dry all the way to the center, usually twice the amount of time as sliced mushrooms.
In my experience, and after talking with others who freeze-dry lots of foods, the best balance for freeze-drying fungi (and fruits and vegetables) is to slice it up before freeze-drying it. Slicing the mushrooms means that you get a better run time on your freeze dryer – usually halving the overall runtime when compared to the whole mushrooms.
And since most dishes call for sliced mushrooms, anyway, it’s not a huge sacrifice. Even then, most recipes that call for whole mushrooms can still be easily substituted with sliced ones.
Pre-Freeze Mushrooms for a Better Freeze-Dried Result
Earlier in the article, we talked about the steps for pre-freezing mushrooms (and the freeze dryer). Now, let’s talk about the reason behind doing so – and it has to do with the “danger zone” of bacterial growth. Think about it with me for a moment.
- If you’re putting frozen food into a room-temperature freeze-dryer, then your food will experience some degree of thawing over the several hours it takes for the freeze-dryer to get going.
- If you’re putting room-temperature food into a room-temperature freeze dryer, then your food is sitting at room temperature for several hours.
Pre-freezing the freeze dryer is an important step in making sure that you keep your food out of the “danger zone” where bacterial growth thrives.
Freeze-drying food will halt any bacterial growth once the food’s properly freeze-dried, but it doesn’t kill that bacteria. Those bacteria cultures are on your food. Those cultures will shorten the overall shelf-life and affect your food once you rehydrate and reconstitute it.
It’s best to avoid all of those issues upfront. So go ahead and pre-freeze both your food and your freeze dryer. This way, you’ve got the safest, best food for the longest shelf-life possible. And once you use it? It’s still the safest, best-tasting food possible.
These steps and recommendations aren’t something that is explicitly listed in the owner’s manual – or talked about a ton in many of the most popular freeze-drying forums. They are mentioned briefly at best. But I wanted to properly explain it here in all of the food handling glory. That way, you’ll know how and why – so that you know it’s more than just for convenience. It’s actually a food safety thing, too.
End the Freeze-Dry Cycle on Warm, Not Cold
Ending your freeze-dryer on a warm cycle isn’t just for convenience. It helps you safely remove food from the freeze-dryer without the food accumulating extra moisture via condensation.
Again, this isn’t something that’s talked about in owner’s manuals or forums. But it is something that we figured out with a trial, and error, and by thinking things through.
Cold things attract water. Think about your glass of ice water in the summer – and how it seems to sweat. Okay, it’s not actually sweating. But it is pulling water out of the air around it. Then, that water sticks to the glass.
It’s the same with your food and your freeze-dryer. If you pull cold food out of a cold freeze dryer, you’re going to get some condensation on your food. And that’s going to affect overall food safety, shelf-life, and quality.
But if you pull the food out during a warm setting? No condensation. No extra moisture. No shortening of the shelf-life of your mushrooms (or whatever else you’re freeze-drying).
Your mushrooms (or whatever else) will last longer, be safer, and not be spoiled by a surprise moisture accumulation.
End your freeze dryer on a warm cycle and skip the surprise condensation.
How to Reconstitute and Use Freeze-Dried Mushrooms
Reconstituting and rehydrating freeze-dried mushrooms is as simple as adding the freeze-dried food to the dish as normal, along with a small amount of water. Cooking the mushrooms in the dish will reconstitute them via the added water, the steam, and the cooking process.
Mushrooms are one of my favorite freeze-dried foods to reconstitute because they’re so easy!
Now, if you want to add some water to them before cooking to reconstitute them, you can. It can make them seem a bit soggier – like if you were going to use canned mushrooms instead of fresh. So if you are going to reconstitute mushrooms, use just small amounts of water in a plastic bag and let it sit. Then, add more water as it’s absorbed.
Or skip that entirely – and do what we do. We just cook with freeze-dried mushrooms – and add a small extra bit of water to the overall recipe as needed.
Then again, my family doesn’t much care about the texture of mushrooms. So if your family is like mine (where they like the flavor but not the texture of mushrooms), then the freeze-dried mushroom powder is the answer. Here’s what you do.
- When you open the Mylar bag (or the mason jar) of freeze-dried mushrooms, pull out what you need for the dish. Re-seal the bag (or jar) as needed.
- Put the mushrooms for the dish into a Ziploc (or off-brand) plastic bag. Remove as much of the air as possible.
- Use a rolling pin to crush the mushrooms.
- Add the mushroom powder (and some extra liquid) to the recipe.
- Enjoy the flavor of mushrooms without the texture.
The only downside to this is that I don’t get to enjoy the texture of the mushrooms. However, I do get to still enjoy the flavor. And even then, there’s a workaround for those of us that like the texture of mushrooms in our food.
- When you pull out mushrooms from storage, pull out a few extra.
- Cook the recipe as normal, with the above modifications.
- Sauté those extra freeze-dried mushrooms in a pan on the stove, separate from the rest of the dish. You may need to add a small amount of water, depending on if you saute them with butter or oil (oil-based sauteed mushrooms seem to need more water, while butter-based sauteeing doesn’t usually need any).
- Add sautéed mushrooms to the plates of those who want them.
Seriously. They’re so easy to use – and I love that they reconstitute in the dish. I’m a fan of easy – and mushrooms are by far one of the easiest foods to freeze-dry, store, and use.
Freeze-Drying Mushrooms FAQs
Let’s make sure you’ve got all of your “how to freeze dry and use mushrooms” questions answered. Here are some of the questions I’ve wondered (and figured out) as well as some of the most commonly-asked questions in forums or asked by someone else just like you.
If you don’t see your specific question (or answer) in this article, please shoot me an email. I’ll try to respond directly to as many emails as I can – and I’ll also get your question (and answer) added to this post. To find out how to email me, click here to go to my contact me page.
When you reconstitute freeze-dried mushrooms, are they soggy?
Some vegetables, mushrooms included, become softer and soggier after having been frozen. These vegetables have the same reaction after having been freeze-dried and reconstituted directly in water. For mushrooms, it’s like you’re using canned mushrooms instead of fresh ones. It’s not bad, but generally fresh mushrooms are better than canned ones.
However, just because they usually become soggy doesn’t mean you’re stuck with soggy mushrooms for life. Read this next question and answer – trust me.
How can you avoid soggy reconstituted mushrooms in a dish?
The best way to avoid soggily rehydrated bell mushrooms is to not rehydrate them before cooking. Just add them directly to the dish while cooking and let the dish’s sauces or steam rehydrate them.
This cooking method works whether you’re making a sauce, a casserole, an omelet, or any other dish I’ve tried so far. And it works with any thinly-sliced, freeze-dried vegetable. Trust me – mushrooms turn out much better this way!
Can you freeze-dry a whole mushroom?
A whole mushroom, depending on the type, takes up to twice as long to freeze-dry as slices do. And even then, some mushroom varieties won’t fit inside of the freeze dryer unless you halve or slice them.
So if you want to freeze-dry mushrooms whole, then your best bet is going to be this: choose smaller mushroom varieties and freeze-dry them like that. Or, if you want to freeze-dry a larger mushroom, then you may need to cut it in half.
It’s as close to whole as you can get – while still fitting things inside the freeze dryer and ensuring that there’s enough surface area for the freeze-drying process to work correctly.
How Do You Freeze Dry Bell Peppers? Freeze-drying bell peppers are very similar to freeze-drying mushrooms. Even so, make sure you read my article and tips for freeze-drying bell peppers here.
How Much Do Freeze Dryers Cost? Freeze Dryers cost between several hundred and tens of thousands of dollars, depending on DIY, make, model, and brand. Read my complete guide to how much freeze dryers cost here.
Are There Foods You Can’t Freeze Dry? Foods high in fats (or oils) and/or sugars won’t freeze-dry well, if at all. Read my article on freeze-drying foods to see the 77 foods you can freeze dry and the 17 foods that never freeze dry.