Dried mushrooms are among the most powerful ingredients available to the home cook, IMHO.
Dried mushrooms are not simply fresh mushrooms minus the diluting bulk of their water. No, no,
no. Depending on how the mushroom was dried, and to a lesser extent on the kind of mushroom being
dried, there are incredibly powerful flavor chemicals in here that simply do not exist
in the fresh specimens. Flavors are not merely concentrated by the drying process. Flavors are
also created by the drying process — new, super powerful flavors. I'm going to show you some
of that science and also talk about how we can actually use dried mushrooms and derived products
here in the kitchen. Yes, we will be discussing the whole sandy dirt problem. But most of all,
I want to try to persuade you to give these things a chance, even if you don't like mushrooms.
The intensely meaty flavor that you get out of this has so many uses in the kitchen.
I increasingly find myself using these instead of stock or stock products. This is nature's bouillon
cube. And if the texture of mushroom skeezes you out, well, you don't actually have to eat them.
The flavor is in the broth. You can treat the mushrooms themselves like kombu and just take them
out, if you want. I suppose that kombu comparison is apt in another way: neither mushrooms nor the
kelp species from which kombu is made are plants. Neither of them are plants. Mushrooms are fungi,
and brown algae like kelp are generally classified by scientists these days as protists, not plants.
This is a fact that I pedantically mutter to myself whenever I see people talking about
vegan meat replacements that contain a lot of fungus or algae as being "plant-based,"
when in fact neither of those things are plants. But I don't want to be the
kind of guy who says that kind of thing. Am I that guy? I think I was just that guy.
Anyway, compared to plants, the basic composition of your typical edible mushroom is surprisingly
similar to that of animal meat. And people dry mushrooms for the same reason they dry meat.
Mushrooms decompose really fast once harvested. We can slow that process to a halt by taking
out the water. Meat is around 75% water. Mushrooms are around 90%. This mushroom,
I dried at room temperature at home by just leaving it in front of a fan for a few days. But
most dried mushrooms you'll find at the store were probably dried with hot air.
Temperatures vary, but a common one used in mushroom drying is 150 Fahrenheit, 65 C. I think
it's fair to call that cooking in addition to drying, and like cooking, it'll kill a lot of the
microorganisms that are present in here, if you hold that temperature for a really long time.
Also, once you get enough of the water out, that's a high enough temperature to
cause the Maillard reaction. And Maillard, of course, is one of the big browning reactions in
cooking that makes amazing flavor. It happens when certain sugars interact with proteins
or protein components in relatively dry, hot conditions. This is a recent literature review
by Chinese and Canadian scientists looking at the chemical composition of dried mushrooms.
And here are some of the flavor chemicals that result from Maillard reaction during drying,
which you can also make through cooking, but there's other stuff going on during drying, like
enzymatic activity. Oh, hey, butyric acid. That's the stuff in parmesan cheese and Hershey bars
that people think taste like puke. Also happening during drying is lipid oxidation and degradation.
Mushrooms contain unsaturated fatty acids and they oxidize during drying, resulting in these complex
chemical interactions that make very strong volatile chemicals — "volatile," in this context,
meaning smelly. Unless you're talking about something like truffles, most fresh
mushrooms have hardly any aroma at all. If you do smell something, it's probably
octenol, or it's also called mushroom alcohol. It's this compound that's responsible for the
earthy smell of fresh mushrooms. The literature shows that octenol and related chemicals
significantly decrease during drying, but the presence of other aromatic chemicals massively
increases. For example, "aldehydes, [other] alcohols, heterocyclic, sulfur and pyrazine
compounds." An example of heterocyclic compounds would be furans. Furans have this fruity,
meaty smell. To me, drying a mushroom really gets you the smell of the forest — the kind of
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Anyway, furans in dried mushrooms — they smell meaty. And speaking of meaty, how about umami,
which of course is a taste, not a smell. We perceive it on our tongue. The umami sensation
is mostly triggered by certain free amino acids, which have broken off from much larger peptide or
protein chains that we cannot taste. The big one associated with umami is glutamic acid.
Surprisingly, we see here in the literature that drying actually reduces the content of
free amino acids in mushrooms. Same deal with the nucleotides that are also associated with umami.
The specifics depend on the drying method. Hot air drying might be the most popular, but there are
other drying methods, like microwave drying, which you can kind of do yourself at home. You gotta
take the power all the way down, and even then that still came out smelling kind of burned.
A fancy new method is vacuum microwave drying. That actually increases the free amino acid
content. But yeah, the conventional methods destroy some of the free aminos and nucleotides.
They get transformed via Maillard and this thing called Strecker degradation into other things
like some of those aromatic chemicals we talked about. But there are still a lot of those umami
chemicals left in here, and they are incredibly concentrated, because dried mushrooms have like
10% of the mass of the fresh ones. Also, I wonder if the free aminos and nucleotides and
such are more available for us to actually taste in dried mushrooms instead of being locked up in
fibrous cell walls or something. I don't see that possibility addressed in that literature review.
But regardless, a tiny package of dried mushrooms like this has all of the umami you need to flavor
a sauce or a soup or a stew or something. I recommend going for the cheap ones. This box of
dried morels was $15. Morels are beautiful, but like truffles, they are relatively rare in the
wild and incredibly difficult to farm. The science shows the flavor of dried mushrooms is chiefly
determined by the drying method, not the species or variety. And I think the textural differences
are almost completely wiped out by drying. So I say just get cheap ones, like these oysters or
these porcini. Now, everybody prepare yourselves. I've got some tough news I've got to break.
I regret to inform you that food comes from the ground. As a result, basically all food is going
to have some dirt and bugs on it, but especially mushrooms, which grow really close to the ground
and which rot really easily, so producers might not want to wash them off during processing.
A little soft dirt is no problem at all. That bit there is probably just pasteurized
compost that this cremini mushroom was farmed in. I don't care if I eat a little bit of that. But
sandy dirt can be a problem, and you'll especially find bits of sand on wild-harvested mushrooms,
like these porcini. Porcini are abundantly foraged in the wild. That gritty dirt is not easily
brushed off, I think because during drying the structure of the mushroom kind of constricts and
grabs hold of the sand. The first thing you have to do is rehydrate the mushrooms in hot water,
stir them around a little bit, let them swell back up and soften. It takes about a half hour, during
which time most of the sand is going to just fall down to the bottom. Very small rocks are not
buoyant, unlike witches. And you could simply fish the mushrooms out, pour the resulting broth — or
"mushroom tea," it's called — pour that out into your food, but leave a little bit behind.
You can see right there in the bottom, that's the sand, and we've effectively removed it. If
you want to be really thorough about it, you can send the broth through a coffee filter. Absolutely
no sand is going to make it through that. In my experience, most of the soluble flavor in dried
mushrooms comes out during that first steep. So we've got it. It's out. Then you can go over and
wash any remaining sand off of the mushrooms themselves without losing too much flavor to
the water. And then you can add those mushrooms to the pan if you plan to use them. Check this out. I
reduced the broth down to a glaze to coat them, a little salt, monter au beurre, and put that
on your burger. All that said, I just throw dried mushrooms straight into my food all the time.
If they're going to get plenty of time in the hot liquid, they should soften up just fine, and the
sand doesn't really bother me. But if it bothers you, look for varieties that have less sand. I
could find no sand at all on these dried oyster mushrooms, probably because oysters are generally
farmed in blocks of sawdust or some such. I'm not sure, but based on my experience, I would guess
that basically any cultivated mushroom is going to have little, if any, sand on it. Oyster mushrooms
or shiitakes are really good. Those are generally farmed, and those are particularly good dried.
But if you don't want to worry about sand at all, well, consider just buying dried mushroom powder.
Once they pulverize the mushroom, they can send it through screens to get out any impurities. A lot
of mushroom powders, or granules like these, will be packaged with salt, which is fine by me.
The food needs salt anyway. And some of them will also be boosted with dried mushroom extract,
where they've used some kind of chemical process to get out more of the flavor chemicals and leave
behind the chitin fibers and stuff that make up the bulk of the dried mushrooms. The result is
an intensely flavorful broth, which is why such products are often found in soup mixes — even the
ones that are not advertised as being mushroom flavor. And I take that fact as evidence that,
even if not everybody likes mushrooms, most people like dried mushroom flavor. So give them a shot.
They are cheap, delicious, sustainable, cruelty-free — what more do you want?