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© Max Straeten / Morguefile.com / CC0 1.0

Mushrooms are not really vegetables because they're not really plants.

Most plants use sunlight to "photosynthesize" to create their own food (the sunlight provides the energy for plants to convert carbon dioxide and water into glucose.) Mushrooms can't do this; instead, they get their food from other plants, usually dead ones, but not always (some will live off of live trees.)

Mushrooms have underground roots. Mushrooms actually grow for quite some time underground before we see them. The aboveground part, what we think of as the mushroom, is basically the "fruit" of the mushroom -- it is grown to create, hold and distribute the "spores", which are the seeds of the mushroom.

Thin filaments called the "gills" grow under a mushroom's cap, where they are protected from rain. The gills produce the mushroom's spores. Not all mushrooms have gills -- for instance, porcini mushrooms don't. Some mushrooms have gills attached right to the stalk; others have gills that aren't attached or only barely. The surface of the gills are covered with a layer called the "hymenium" which produces the spores.

Not all mushrooms have stalks. When mushrooms have a ring around their stalk, that ring is called the "annulus." Almost all mushrooms need spore from another mushroom to pollinate them in order to produce a mushroom. Agaricus Mushrooms are an exception to this.

Organic mushrooms may be a bit of a con. Most growers don't need to use chemicals, anyway, because cultivated mushrooms have to be grown in sterile environments -- and remember, anything such as chemicals is an added expense for producers, so if they can avoid using them, they will.

Mushroom Spawn is mushroom spore mixed with sterilized grain. The spore is then allowed to germinate on the grain. Suppliers sell the mushroom spawn to mushroom farmers.

What soil you see on your standard supermarket white mushrooms isn't soil and it isn't manure. It's almost always peat moss:

"...bear in mind that any brown dirt you see isn't manure: it's probably sterilized peat moss, with which the growers cover the composted substrate and through which the mushrooms actually poke their little heads." (( Wolke, Robert. What Einstein Told His Cook: Kitchen Science Explained. New York: W.W. Norton & Company. 2002. Page 287. ))

Many Foodies advise only to buy pure white mushrooms whose caps haven't opened yet. This is probably by association with fruit and vegetables: when browning happens to them, it is generally a bad thing. As far as mushrooms go, though, it's really a matter of what you prefer. What the Foodies should be saying is, if you don't like strong mushroom tastes, or if you are cooking for children and need to keep everything as inoffensive as possible as you introduce them to new things, then choose the pure white young ones -- because they hardly have any flavour.

Mushrooms generally reach supermarkets within a day of picking, because everyone wants to buy them while they are pure white. The darker the white button mushroom, however, the richer the flavour. Flavour only starts to develop as the cap opens up and the mushroom develops, and the kicker is, these are the ones that get marked down. Enjoy them at bargain prices while you can -- remember what happened to Cremini mushrooms. When they got "old", dark and big, no one would buy them so they used to just throw them out. Then someone gave the older, bigger, darker ones a new name and presto -- Portobello Mushrooms were born, with a premium price to boot.

What causes dishes to darken when you add mushrooms to them is the spores coming out into what you are cooking. Young white mushrooms haven't had a chance to develop those spores yet. If you making a light or clear dish, then you will probably want to use the white button mushrooms. Otherwise, if you actually want good tasting mushrooms, get the ones that everyone else leaves behind.

In Japanese cooking, mushrooms are almost never eaten raw, always cooked.

Half the mushrooms grown in America are grown in the south-east corner of Pennsylvania.

Autumn Mushrooms

In nature, these grow in the autumn, as the name would imply. They tend to have rich, earthy flavours that can stand up well to strong tastes like garlic. They will also fry up well and hold their taste through it.

Spring Mushrooms

In nature, these grow in the spring. In England, for instance, St George's Mushrooms always start to appear on St George's Day, the 23rd of April. Spring Mushrooms tend to have a milder, more delicate taste that is better with other milder flavours.

The myth about soaked mushrooms absorbing water

It's a myth that soaking mushrooms in water will cause them to absorb a great amount of water.

What we are told is that mushrooms are like a sponge and will sop up water and get mooshy.

The myth goes back to at least the 1937 edition of Larousse Gastronomique.

Noted food researcher Harold McGee has disproved this. For his 1990 book, the Curious Cook, "he soaked 252 g of mushrooms in water for five minutes, blotted off any surface moisture, then weighed them again. They'd soaked up a mere 6 g, or a sixteenth of a teaspoon each – so briefly rinsing mushrooms is unlikely to make much difference at all." [See page 182 of McGee, Harold. The Curious Cook. New York: Hungry Minds Inc. 1990] ((Cloake, Felicity. Should you wash mushrooms? Manchester: The Guardian. 2010.))

In an online forum, McGee added:

"I was skeptical about the mushrooms-absorb-water idea and so did the soaking experiments with standard white mushrooms for “The Curious Cook” back in 1990. I’ve since tried a number of others, and if you make sure to shake the water out of the nooks, fresh mushrooms absorb little if any water. I’d also say that since they’re already around 90% water, a little more or less isn’t going to make much of a practical difference in the subsequent cooking. Now losing flavor to the water is a different question, and it’s possible that you might lose savory amino acids (aroma molecules tend not to be soluble in water). Even here, though, the amino acids are inside cells, and most cells are not going to be breached by surface exposure to water. So I wash my mushrooms with a clear conscience." ((McGee, Harold. Chef Talk Forum. Posting of 14 December 2005. Accessed July 2016 at .http://www.cheftalk.com/t/15774/a-clean-shroom-is-a-happy-shroom#post_122136))

Robert Wolke, author of 'What Einstein Told His Cook', repeated and confirmed McGee's findings about soaked mushrooms absorbing only trace amounts of water:

"I have repeated McGee's experiment with two 12-ounce packages of white Agaricus mushrooms (a total of 40 mushrooms) and a 10-ounce package of brown ones (16 mushrooms.) I weighed each batch carefully on a laboratory scale, soaked them in cold water with occasional stirring for McGee's five minutes, threw off most of the water in a salad spinner, rolled them around in a towel, and weighed them again. The white mushrooms, all tightly closed buttons, had absorbed only 2.7 of their weight in water. That's less than three teaspoons of water per pound of mushrooms, in agreement with McGee's result. The brown mushrooms retained more water: 4.9 percent of their weight or five teaspoons per pound. That's probably because their caps were slightly separate from the stems and water was trapped in the gill spaces, not because their flesh is any more absorbent. Many other irregularly shaped vegetables would mechanically trap small amounts of water. And the timid 'quick rinse' recommended for mushrooms by many cookbooks might trap just as much as my five-minute soak did." (( Wolke, Robert. What Einstein Told His Cook: Kitchen Science Explained. New York: W.W. Norton & Company. 2002. Page 287.))

In 2009, the French Culinary Institute of New York reported that even if there were some water clinging to the gills of mushrooms, that that wasn't a bad thing. They concluded that it might cause mushrooms to absorb less oil when fried in oil:

"While the mushrooms are boiling off their water, they aren't absorbing oil. By the time the boiling stops they have already collapsed, so they aren't as porous as a raw mushroom and don't want to absorb oil. The dry mushrooms start absorbing oil from the get-go." ((French Culinary Institute of New York. Blog posting 21 December 2009. Accessed July 2016 at .http://cookingissues.wordpress.com/2009/12/21/crowded-wet-mushrooms-a-beautiful-thing/))

Julia Child merrily washed her mushrooms, in the first ever episode of the French Chef, (broadcast 11 February 1963). She felt it was important to do so to get any residual sand off them:

Child felt, however, that water left on the mushrooms would prevent them from browning as nicely:

"They've got to be absolutely dry....so you take a nice clean towel and you dry them off, because if they're wet, they're not going to brown." ((Julia Child. The French Chef. Episode 1. 11 February 1963. 14:15 mins))

Still, food researchers since Julia Child feel that the wetter the better when you are cooking mushrooms:

"Most books tell you that the pan needs to be hot when you saute mushrooms; otherwise, they release too much moisture as the pan heats up, and you end up stewing them instead. But as it turns out, the mushrooms that start in a cold pan — and more importantly, a crowded pan — are the real crowd-pleasers. They don't absorb as much oil as mushrooms that are added to a hot pan, and as it turns out, oily mushrooms don't taste as good as non-oily mushrooms. "Why do you hate mushrooms?" Arnold now demands of anyone he sees not crowding mushrooms in the pan. "You must crowd the mushrooms."

Arnold wrote about a variation of this demonstration on his blog in 2009, focusing on wetness vs. dryness, but not pan temperature. The key is that the wet mushrooms (soaked before cooking) aren't absorbing oil while they're giving off moisture, and by the time all the moisture is gone, the mushrooms have become less porous — and less ready to absorb oil. Meanwhile, the dry mushrooms start absorbing oil as soon as they hit the pan. So, the wetter and soupier the mushrooms, the better. ((Eater.com blog. Dave Arnold and Harold McGee Bust Food Myths at Harvard. Blog posting 9 September 2014. Accessed July 2016 at .http://www.eater.com/2014/9/9/6159023/dave-arnold-and-harold-mcgee-bust-food-myths-at-harvard ))

Discoloration of mushrooms

Some people note that washing or rinsing mushrooms can sometimes cause a purplish coloration on the skin. Researchers don't understand yet the exact enzymatic or chemical reason why this occurs. ("Structural characterisation of the purple pigments formed in model systems proved difficult due to their instability, and for similar reasons, it was not possible to isolate, purify and characterize the purple pigments produced in washed mushrooms.") (( Adams, J.B. and Brown, H.M. Discoloration in Raw and Processed Fruits and Vegetables. Crit Rev Food Sci Nutr. 2007;47(3):319-33.))

If this is a concern, or to prevent darkening, try any of these:
  • 3 grams (1 teaspoon) pure ascorbic acid to per 4 litres (US quarts) of water;
  • 6 x 500 g Vitamin C tablets crushed and dissolved into 4 litres (US quarts) of water; (( United States Department of Agriculture (USDA). Complete guide to home canning. Agriculture information bulletin No. 539. 2015. Page 1-11. ));
  • 1 teaspoon lemon juice per 500 ml (2 cups) of water;
  • 1 1/2 teaspoons citric acid per 500 ml (2 cups) of water (( Andress, Elizabeth L. and Judy A. Harrison. So Easy to Preserve. University of Georgia Cooperative Extension. Bulletin 989. Sixth Edition. 2014. Page 285 ))

Out of all of those, pure ascorbic acid is considered by professional home food preservers to be the best.

Cooking Tips

Some wild mushrooms will require soaking in salted water to dislodge insects hiding in the gills. Others may require peeling to remove skin that may cause stomach upsets.

You may clean mushrooms however you wish: by wiping them with a damp paper towel, by rinsing lightly under cold running water, or, by soaking in water. (See discussion above of soaking mushrooms.)

The standard advice used to be to pat them dry before frying, but now that is disputed (See discussion above.)

Most mushrooms you use stalk and all. You just trim and discard the thinnest slice off the end of the stalk, and then chop or slice as needed.

Some mushroom stalks, such as those of Portobello, are too tough to be eaten raw: these can be tossed in the freezer for future use either in a stock, or chopped and incorporated into a recipe. If your recipe calls for just mushroom caps, you can pull the stalks out with a gentle twist and tug. Sometimes the recipes will have you chop up the stalks and incorporate these into what you are making. If it doesn't, bag and freeze these as well for future use.

Some recipes will have you remove the gills from larger mushrooms. This has nothing to do with the gills being bad for you: far from it. Rather, it's usually to make room for more stuffing to go in. If you do these, toss the gills into a small freezer bag and freeze for future use. At the price you paid for those mushrooms, why not? A good deal of a mushrooms flavour is in those gills.

Cooks used to feel that mushrooms are better cooked quickly than slowly, but recent research appears to be disproving that.

To sauté: heat oil or butter in a large frying pan. Use about 1 tablespoon of fat per 200 g (1/2 lb) of mushrooms. Add mushrooms, and cook and stir for about 5 minutes, uncovered. At that time they should be golden and ready to serve or use. If your mushrooms seem to be steaming but not gaining any colour, you may have put a lot of mushrooms in small pan. Again, cooks used to consider this an error in judgement, but modern food researchers do feel that this is exactly the way to go for better flavour.

To microwave: no butter, water or oil is technically required. Put half your mushrooms in a covered bowl, place in microwave, and zap on high until they begin to water. Then stir in the remainder of the mushrooms. For 200 g mushrooms (1/2 lb), sliced, cook for a further 2 to 3 minutes. The idea with adding the remainder part way through when there is some juice is that mushrooms that aren't covered in some kind of liquid in the microwave can come out tasting a bit odd. For even better taste, toss the mushrooms at the start in chopped garlic and two tablespoons of oil or melted butter.

If you are microwaving mushroom caps for a stuffed mushroom recipe, be careful not to overcook them as they will shrivel if over-zapped.

To grill or broil: brush large mushrooms with oil or melted butter, season to taste, and grill about 5 minutes on each side. You may baste them with more melted butter or oil during grilling.

If you are planning on serving fried mushrooms as a side dish, allow about 175 g (6 oz) raw per person.


Mushrooms have some trace amounts of riboflavin, niacin and pantothenic acid (which helps the bodies to produce hormones and our nervous systems to function.) Beyond that, not really much nutritional value -- they are mostly enjoyed for their flavour and texture.

Mushrooms are about 90% water.

Fresh and dried mushrooms have no sodium in them, but commercially canned mushrooms can be very high in sodium: anywhere from 500 to 800 mg of sodium and up per 8 oz / 1 cup, drained (284 ml / 10 oz can before draining.) In comparison, mushrooms canned either commercially or home canned without added salt will only have about 30 mg of sodium for the same amount.

Draining the tin of mushrooms with added salt, then emptying them into a bowl of water and swooshing them around may wash some of the sodium off.

Fresh mushrooms are 0 Weight Watchers PointsPlus® when consumed on their own. In a recipe, the cost is 3 Weight Watchers PointsPlus® per 500g (17 1/2 oz.)


1/2 pound (225g) fresh sliced mushrooms = 2 cups fresh sliced = 1 cup cooked

750g (1.65 pounds) fresh large white or chestnut mushrooms, quartered = 8 cups volume
4 oz sliced mushrooms, canned = 2/3 cup drained
1 pound (450g) fresh mushrooms = 12 oz tinned, undrained = 6 oz (170g) drained = 20 to 30 medium mushrooms = 3 oz (85g) dried = 6 cups fresh slices = 2 cups sliced and cooked

Storage Hints

The main principle behind storing mushrooms is that you want to discourage sweating, moisture accumulation and condensation during the short time that you can keep them, as this will cause them to spoil even faster.

First, don't wash them before you are ready to use them. Secondly, store in fridge. If they have come in a shrink-wrapped container, remove the plastic wrapping. Ideally, the best thing to store them in is a paper bag, as the paper gives you the right combination of letting excess moisture out while keeping enough in. If you haven't got a paper bag, wrap them in a paper towel, and then put them in a plastic bag whose top is left partly open. Use within 4 days.

"Q-I have seen mushrooms in produce sections that are turning colors and moldy. Some are even slimy to the touch. I realize that the mushroom is a fungus, but the new fungus that keeps growing on it-will that make you sick? Anthony Urbanik, Lindenhurst.

A-"Some chefs like mushrooms that are slightly discolored because they feel mature mushrooms have a slightly more developed flavor," says Charles Harris, executive director of the American Mushroom Institute, Kennett Square, Penn. "But if the mushroom is greatly discolored, or if it feels slimy -- which indicates excess bacterial growth on the surface -- then the mushroom should be discarded." Harris adds that mushroom lovers should remember that a slimy, discolored mushroom probably would not make you sick; it is merely unappetizing in appearance. However, at a certain point in the deterioration the flavor and aroma of the mushroom are adversely affected," he says.

Harris adds that mushrooms retain some respiratory capabilities, even after being picked; consequently the best way of storing them is to put them in the refrigerator in a light, thin brown paper bag, which will allow them to breathe. "Ideal temperature for mushroom storage is 34 degrees," he continues, which is close to the temperature of many refrigerators." ((Magida, Phyllis. Slightly Off-color Mushrooms Are Safe To Eat. Chicago: Chicago Tribune. 21 January 1988.))

Preserving Mushrooms

Mushrooms can be preserved by freezing, drying, or home canning (either pickled or plain.)

Note: The University of Georgia reminds us that "the toxins in poisonous varieties of mushrooms are not destroyed by drying or by cooking. Only an expert can differentiate between poisonous and edible varieties." (( Andress, Elizabeth L. and Judy A. Harrison. So Easy to Preserve. University of Georgia Cooperative Extension. Bulletin 989. Sixth Edition. 2014. Page 351. ))

So neither freezing, home canning, or drying will make a poisonous mushroom safe to consume.

The longest ways to preserve mushrooms with the best quality are considered drying and home canning.

Note that the home canning directions were designed for the standard white Agaricus button-type mushrooms. If you have speciality mushrooms to preserve, freeze or dry them.

Freezing Mushrooms

Some people will say that mushrooms don't freeze well, because they come out more strongly flavoured. Others retort that only people who don't actually like mushrooms would find that a problem.

Some say that frozen mushrooms are darker. Others retort that only those who have only ever seen cello-wrapped white button mushrooms at a supermarket would be surprised to see a brown mushroom.

When you go to use frozen mushrooms, they will be good for frying, sautéing, or using in cooked dishes such as stews, soups, meat loaves, pâtés, risottos, etc. Freezing concentrates their taste and makes it richer and heartier.

Don't thaw frozen mushrooms before using: just add them into what you are cooking.

There are three generally used methods of freezing methods. One is freezing as is, the others are steam blanching or frying before freezing.

The first is a casual one practised by many people, who report that they find the results just fine for their tastes and needs.

Freeze as is
Wash mushrooms. Slice or leave whole. Pack into plastic bags or containers, freeze. Use within 3 to 4 months.

The second two -- steam blanching or frying -- are those recommended by the USDA, as found in So Easy to Preserve.

Freezing Mushrooms
Preparation – Choose mushrooms free from spots and decay. Sort according to size. Wash thoroughly in cold water. Trim off ends of stems. If mushrooms are larger than 1 inch across, slice them or cut them into quarters.

Mushrooms can be steamed or heated in fat in a fry pan. Steamed mushrooms will keep longer than those heated in fat.

To Steam – Mushrooms to be steamed have better color if given anti-darkening treatment first. To do this, dip for 5 minutes in a solution containing 1 teaspoon lemon juice or 11/2 teaspoons citric acid to a pint of water.

Then steam whole mushrooms 5 minutes, buttons or quarters 31/2 minutes and slices 3 minutes. Cool promptly, drain and package, leaving 1/2-inch headspace. Seal and freeze.

To Heat in Fry Pan – Heat small quantities of mushrooms in margarine or butter in an open fry pan until almost done.

Cool in air or set pan in which mushrooms were cooked in cold water. Pack into containers, leaving 1/2-inch headspace. Seal and freeze.

(( Andress, Elizabeth L. and Judy A. Harrison. So Easy to Preserve. University of Georgia Cooperative Extension. Bulletin 989. Sixth Edition. 2014. Page 285 ))

Drying Mushrooms

These directions come from So Easy to Preserve:
"Scrub thoroughly. Discard any tough, woody stalks. Cut tender stalks into short sections. Do not peel small mushrooms. Peel large mushrooms. Slice. No blanching required. Estimated drying time dehydrator (hours): 8 to 10." (( Andress, Elizabeth L. and Judy A. Harrison. So Easy to Preserve. University of Georgia Cooperative Extension. Bulletin 989. Sixth Edition. 2014. Page 350 ))

Home Canning Mushrooms

  • Plain home canned mushrooms must be canned in a pressure canner at 10 lbs pressure adjusted for altitude for 45 minutes in 1/4 or 1/2 litre (1/2 or 1 US pint) jars. See our satellite site healthycanning.com for complete directions on http://healthycanning.com/canning-mushrooms/" target="_blank">canning plain mushrooms.
  • Pickled mushrooms are packed in jars with a vinegar solution, based on a modern, tested safe canning recipe, and then the jars are processed either in a steam canner or water bath canner. See our satellite site healthycanning.com for complete directions on http://healthycanning.com/marinated-mushrooms/" target="_blank">pickled mushrooms.

When home canning, it's important to always use only modern, tested directions from reputable sources for the highest safety and quality. Do NOT use any canning guides or directions prior to 1994.

History Notes

Greeks and Romans considered mushrooms delicacies.

The Romans used the word "fungus" to refer to mushrooms, toadstools and all fungus in general, and Boletus to refer to mushrooms. A Boletus was used to poison Claudius, introduced by his cook Locusta under the orders of Agrippina, his fourth wife. Claudius died aged 64 within 12 hours of eating the mushrooms. She killed him because Claudius had decided that his own son would succeed him, but Agrippina wanted the position of Emperor to go to her son, Nero. Nero ironically referred to this mushroom as the "food of the gods" for knocking off his uncle / step-father, Claudius.

Now we use the word "Amanita" to designate the group of the deadliest of mushrooms, but the Romans seem to have used the word "Amanita" to mean a kind of good mushroom, as the writer Galen recorded that Amanita was good to eat.

Champignon in French is a generic word for mushrooms and toadstools, coming from the word "champ", meaning "field".

Only the English language distinguishes between mushrooms and toadstools.

The first book on mushroom growing was Mushrooms: How to Grow Them; A Practical Treatise on Mushroom Culture for Profit and Pleasure, written in 1891 by William Falconer of Dosoris, Long Island. Gripping reading for those restless nights.

Up to 1903, America was importing mushroom spores from England that was in poor shape by the time it arrived. In that year, United States Department of Agriculture scientists developed their own reliable source of spawn. Synthetic manure to grown mushrooms in was developed in 1930.

Techniques for cultivating wild mushrooms on sawdust were developed in the 1950s.

Literature & Lore

"Life is too short to stuff a mushroom." -- Margaret Storm Jameson (English novelist, 1891 - 1986).

"The grisly todestool grown there mought I see, And loathed paddocks lording on the same.." -- Edmund Spenser (1552-1599). "Faery Queen".

"Mushrooms Mrs. Rorer regards as a desirable food because of their exceedingly nitrogenous character. They will give you meat value. There are 135 varieties of mushrooms. In the locality in which Mrs Rorer resides many of the people are afraid to eat them and so, she laughingly declared, it leaves about ten bushels for herself. Among puff balls are no poisonous varieties." -- Jorgenson, Judith. Around The Evening Lamp. Des Moines, Iowa: Des Moines Daily News. 2 June 1896. Page 2.

Language Notes

The English word mushroom comes the French word "mouceron" (older French: mousseron), which meant just the "A. prunulus" variety which would grow in moss, thus the name. Someone who eats mushrooms is called a "mycophagist." The study of mushrooms is called "mycology."


Cloake, Felicity. Should you wash mushrooms? Manchester: The Guardian. 2010

Freedman, Louise and the Mycological Society of San Francisco. Wild about mushrooms, Part III -- Truffles. San Francisco, 2000. Retrieved from online edition .http://www.mssf.org/cookbook/index.html 27 Jan 2004.

Provincia di Cuneo. "Funghi in Provincia di Cuneo: Funghi Commestibili". Retrieved from Provincia di Cuneo website .http://www.provincia.cuneo.it/grandambiente/funghi/index.htm in June 2004.

See also:


Bay Boletus Mushrooms; Brick Top Mushrooms; Cauliflower Mushrooms; Cloud Ear Mushrooms; Corn Smut; Dried Mushrooms; Enoki Mushrooms; Hen-of-The-Woods Mushrooms; Hoshi Shiitake; Marinated Mushrooms; Mushroom Butter; Mushroom Cutters; Mushroom Fumet; Mushroom Gills; Mushroom Ketchup; Mushrooms; Nameko Mushrooms; Oyster Mushrooms; Shiitake Mushrooms; Shimeji Mushrooms; Snow Mushrooms; Stipe; Straw Mushrooms; Truffles; Wild Mushrooms; Wood Ear Mushrooms

Please share this information with your friends. They may love it.

Also called:

Champignon (French); Pilzen (German); Funghi (Italian); Championes, Setas (Spanish); Boletus, Fungos (Roman); Kinoko (Japanese)


Oulton, Randal. "Mushrooms." CooksInfo.com. Published 17 April 2001; revised 18 February 2011. Web. Accessed 10/27/2016. <http://www.cooksinfo.com/mushrooms>.

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