Cultivated Mushrooms Part 2: The Exotics

Elizabeth Schneider / July 1998

Hunting mushrooms for your menu? Let Elizabeth Schneider be your guide. This second in a series addresses the more unusual cultivated varieties.

Read Part 1 of this series, The Dependables, here.

Wild as they may be in the sense of far-out, many "wild" mushrooms are now grown under strict laboratory conditions, not murmuring pines. Unlike their wild kin, these man-monitored fungi offer the advantages of availability and safety: they can be ordered when you want them (more or less), and they are not questionable species, which do shot up in foragers' baskets. Best of all, they are bug-free, worm-free, mud-free, stick-free, sand-free, and never rain-soaked. For restaurants, this means reduced labor costs and less waste than for foraged fungi. On the other hand, cultivated mushrooms can lack the character, aroma, and mysterious flavor of forest-born fungi, as well as the cachet of wild things.

In the April 1998 issue of Food Arts I covered the more common cultivate mushrooms: white buttons, cremini, portobello, common oyster varieties, shiitake, and enokitake. In this issue, I'll pick through the more exotic and hard-to-find species, in alphabetical order. (Note: Cultivated morels, which are only available in relatively small quantities at present, will be explored, along with wild morels and other seasonal mushrooms in a future issue of Food Arts.)

Beech Mushroom, Clam Shell, and Honshimeji (Hypsizygus tessulatus) are three names for a single mushroom. (If nomenclature interests you, read on; if not, skip to the next paragraph.) When this cute, sturdy mushroom first appeared in the United States about a decade ago, it was marketed as "hon-shimeji." Since then, "the general name 'Shimeji' has been assigned to about 20 species, causing widespread confusion amongst amateur and professional mycologists," writes Paul Stamets in Growing Gourmet & Medicinal Mushrooms (Ten Speed Press, Berkeley, CA, 1993), "Scientific articles have attempted to clarify what is the 'true Shimeji' which Japanese call Hon-Shimeji," and which is now understood to be a species of the "Lyophyllum...not commercially cultivated." He explains that the "confusion is understandable because young specimens [of it]...look very similar to Hypsizygus tessulatus, known in Japan as Buna-shimeji or the Beech Mushroom."

"Beech" is the name chosen by the country's largest specialty grower, Phillips Mushroom Farms in Kennett Square, Pennsylvania. Whether pure white or tan, it has smooth, small, thinnish caps with sharply defined ivory gills and thick, tender stems. Gourmet Mushrooms in Sebastopol, California, has trademarked its strains as the Brown Clam Shell and Alba Clam Shell. Other growers and importers sell Hypiszygus as "honshimeji." (For the record, the goofy "honeyshmeggie" I saw on a distributor's list fits no mushroom!)

Although there is variation from grower to grower, generally speaking, the mushroom retains its sprightly bounce and clear color when cooked quickly over high heat. Its flavor is mild, with a hint of herbs and nuts, its texture fleshy and juicy, with a crisp edge. White beech seem to be less solid and wetter. Sautéed, both types gild prettily.

Look for solid specimens with a minimum of heavy base and no trace of dampness. Prepare by trimming off the thickest part of the base or growing medium to separate the stalks, which should be kept intact. To cook, toss with oil, salt, pepper, and a dash of acid to coat lightly. Roast in a hot oven until tender, a matter of three to five minutes. Or slow-roast at lower heat for an earthier flavor. Or sauté or simmer in soup.

Blewit, pied bleu, or "bluefoot," only recently imported to the United States, is popular in wild and cultivated forms throughout Europe. Its scientific name has changed so many times in recent decades that mycologists often refer to it by its common name, blewit, a name that has stuck for hundreds of years. The name "bluefoot" (a recent marketing name) hardly describes the cultivated ones arriving from France, which have very violet stems. Exceptionally dense, heavy mushrooms, the indented beige caps are solid, satiny, and taut. Melded twins or triplets are common. Lightly earthy, mild, meaty, and with a slight grainy flavor, they are low on aroma—unlike their wild counterparts.

Seek bright color for freshness; the violet fades with age—and with cooking. Caps are choice, stems less so. Although quite sturdy in general, the mushroom has brittle gills that spoil quickly; sniff for signs of spoilage. Cultivated blewits need only a bare trim. Keep large caps whole for grill or roasting; or stuff and bake. Cut off chewy stems and chop for soup, stuffing, stock, sauce, or stew.

Cinnamon Cap and nameko are both species of Pholiota: the first, a trade secret; the second, Pholiota nameko. Both are notable for their caramel color and slippery texture, particularly nameko. The Cinnamon Cap, firm and tawny, grows in small clumps; its sturdy, thickish white stems are rather rough looking. Separated and sautéed, they brown beautifully, the caps becoming juicy and toasty-tasting, the stems slightly crunchy—but not as fibrous as they appear.

The small-capped, slender-stemmed nameko cooks quickly to a sweet, earthy savor and exaggerated soft slipperiness that make it a favorite in Japan, where such textures are appreciated. Both Pholiota have an un-American slurp that suits Asian broths and those who fancy them.

Hen of the woods or maitake in Japanese (Grifola frondosa), no kin to chicken of the woods or fried chicken mushroom, has a flavor, scent, and texture that sets it pleasingly apart from most farmed species. Garlicky and autumnal in aroma, the nutty flesh is firm and a bit crumbly. Even when cooked it has a wild leafy look and dynamic tone—tender with an al dente bounce. Cultivated forms are milder than wild, as well as daintier. Wild can range from three to 100 pounds per clump. The "hen" is an aggregate of clusters of small, overlapping irregularly spoon-shaped caps (or "feathers").

Grown in great quantities in Japan, cultivated production in this country is minimal, primarily because the mushroom itself fruits unpredictably, according to Don Phillips, president of Phillip Mushroom Farms. "It's an unstable producer, sometimes yielding plenty, sometimes nothing," he laments. he makes no promises, but "production should be increased and maintained as of 1998—at long last!" he says.

Look for fluffy "feathers" and comparatively little heavy core—although it is edible and good. Sniff for hints of sourness or for no aroma—which means the fungus is dried out. Check the caps for signs of decay on the edges.

Prepare by tearing into branchlets, paddles or chunks, pulling apart the heavy base. If growing medium adheres, trim it off. The spongy, chewy flesh benefits from slow cooking with liquid. Braise pieces with olive oil, garlic, stock, and pancetta; or stew in cream and brandy. Unlike wild, the cultivated is tender enough to sauté.

Huitlacoche, cuitlacoche, maize mushroom, or corn smut (Ustilago maydis)—does one classify as "semi-cultivated" a fungus that grows inside a cultivated crop? Whether it occurs spontaneously or is introduced by inoculation, the curious growth called huitlacoche (its Nahuatl name) develops darkly inside corn kernels, swelling them to baroque forms. The inky edible is dense and pasty, but milder than its ominous look suggests.

Huitlacoche-engorged ears of corn, from white to red to blue to black, line market stalls throughout Mexico, where the delicacy is best appreciated (although I hear it sells out on arrival in the Paris market as well). "I though that in New York I'd have a hard time selling this weird black 'Mexican truffle,'" says Josefina Howard, chef/owner of Rosa Mexicano in New York City, "but it has been unbelievably popular—universally accepted in a way I've never seen with any other food," she marvels. "People clean their plates, they never send it back, they call to see if it's on the menu. I must use 100 pounds a week—unless I can't get it, which happens often."

Availability seems to be the biggest problem for the half-dozen chefs I spoke with who have use huitlacoche. The one grower I located asked not to be identified because he has no more to sell. In season (summer), farmers' markets seem to be the only fresh source. Excellent frozen huitlacoche kernels are available on and off from mushroom distributors. Kernels should be full and fat, not shriveled, broken, or cracked. Chef/owner Rick Bayless (Topolobampo and Frontera Grill, Chicago), who gets his fresh from a local organic grower, spreads kernels on a sheet pan and stores them at the top of the walk-in ("they're fragile and shouldn't be bumped"). He finds they last as long as two weeks. Or he wraps kernels tightly in plastic and freezes "without loss in texture or taste."

To prepare fresh kernels, go over them with a soft brush, flicking off sand or mud. Or rinse and dry gently. Typically, huitlacoche is precooked, whether or not it will be further cooked, says Bayless. Sauté onion, then add a bit of garlic, chile, and chopped, whole tomatoes. Add chopped fungus and epazote; cook gently for 15 minutes to blend flavors. Because it is intense and a bit grainy, huitlacoche benefits from blends and contrasts: "Texture balance is paramount and the flavor must come out without dominating," stresses Bayless.

Oyster mushrooms (Pleurotus species) are cultivated in more shapes, sizes, and colors than any other mushrooms. Why? Because, for the most part, they are relatively easy to cultivate and grow fast. Common buff and grey osteatus species were discussed in Part 1 (Food Arts, April 1998). Other related species follow:

Blue oyster, or hiratake in Japanese, is also referred to as "Shimeji" on some lists, but this former catchall term for Pleurotus species is now considered incorrect. The satiny, small, bluish mushrooms are more solid and tastier than most oyster species (although they usually do fade to taupe, like most oysters). Ones I've sampled taste sweetly shrimpy, shrink little, and retain their shape and springiness. Use as a textural contrast rather than as a blend-in mushroom.

Prepare bu cutting apart at the base. Cook briefly, sautéing a few minutes to brown lightly. Or sauté, then add liquid to cook through and cream to glaze.

King oyster or Trumpet Royale (Pleurotus eryngii)—large, heavy, and fleshy—is unlike any other cultivated oyster, although it is one, despite its trademark name, which seems to link it to trumpet mushrooms (such as the trompette de mort). Although there is great variation in quality, the cashmere tan-capped beauties should be thick and solid. "Their density seems to hold up to any cooking circumstances," says executive chef Michael Otsuka (Pacific Restaurant, San Francisco). "They're fail-safe unless you walk away and let them burn."

To prepare, trim bases just enough to separate. Large ones are best sliced lengthwise in several strips "like string cheese," as does Otsuka. Or cut apart cap and stem, slicing the bright-white stem into rounds that cook up as juicy as scallops. Braise or stew, using plenty of liquid to tenderize the solid flesh. Or toss with nut oil and a little lemon and roast in a high oven until crisped on the outside and tender and juicy within; cooked this way, you'll want to eat them separately with your fingers—like fried clams.

Pink oyster (Pleurotus djamor and other) "has a shelf life of two hours," says Hans Johansson of Hans Johansson's Mushrooms and More, a distributor based in New York City's suburban Westchester County. So true is this statement that I have never managed to test them. I have tried three times, only to find them so nasty by the time I was ready to cook (no more than 24 hours after purchase) that they had to be tossed.

Yellow oyster (Pleurotus citrinopileatus and others) that I tested were nearly as perishable as the pink, but lasted long enough to cook. Whether sautéed, roasted, steamed, or braised, the yellow color disappeared, as did the taste, which was little more than bitter to begin with. Three out of three batches disappointed this cook.

White trumpet or angel trumpet (Pleurotus ostreatus kummeri) is also difficult to recognize as oyster, since it, too, is trumpet-shaped and -named. I have seen two distinct versions: one—pearly, smooth individual funnels—cooked to mild softness reminiscent of scrambled eggs; the other—clustered, near-translucent, with overlapping caps as pretty as seashells—cooked up wet and nearly tasteless.

Serve white trumpets in clear soup, where you'll get your money's worth visually: soft fluted shapes wave like sea anemones. Simmer the whole trumpets (or trimmed and partly separated clumps) in clear broth just to wilt. For a sauté, if you prefer, halve large ones lengthwise and leave smaller ones whole. Sauté gently in a little grapeseed oil and butter just to barely cook through; finish with a little more butter and mild herbs.

Pompon Blanc or bear's head tooth (Hericium erinaceous) looks like a powder puff crossed with mozzarella. This tidy cultivated form of a huge, shaggy forest mushroom is among the most curious on the market. Rounded, spongy, almost furry in texture, each pet pouf weighs in at about one to three ounces and has a texture quite unlike other cultivated types. It was Jacky Robert (then executive chef at the defunct Ernie's in San Francisco, now dining room chef at Maison Robert in Boston) who named it in the 1980s with a French sailor's cap in mind. Although it has been available in limited quantity since that time, it remains a novelty, with chefs running hot and cold about its charms.

Accept only the driest specimens, without discoloration. Roast in a hot oven until there is only a little resistance in the center, a matter of a few minutes. The flavor is hard to pin down: light, a bit bitter, with a suggestion of seafood and asparagus. Or sauté: cut 1/4-inch slices (which are pretty and uniform) and sauté in oil and butter until well-gilded on both sides, turning carefully. Blot on toweling, as it absorbs considerable fat.

Wood ear, cloud ear, or tree ear (Auricularia species) is a thin, floppy, near-translucent, whorled, black or brown mushroom shaped like... an ear, not surprisingly. Widely available in dried form, it is a staple in hot-and-sour soup and other traditional Chinese dishes. For my taste, the dried—although remarkable in its ability to rehydrate to its original form—reveals little of the leafy aroma of fresh, nor its springy-soft consistency. But the texture for which it is loved in Asia makes some Americans uneasy: slightly gelatinous, almost crunchy. Its origins might as well be the ocean floor as the forest's. Like dried, fresh caps vary in size from that of a quarter to a saucer.

I hear that unscrupulous distributors rehydrate dried and sell it as fresh. I do not know the truth, but wood ear I know to be fresh is cool, damp, and firm, with a jellyfish feel, devoid of slime or mushiness. Fresh, it keeps for a week or two and can be frozen without loss of character. Rinse to use. Executive chef Gary Palm (Mission Inn, Riverside, CA) trims the knots at the back of the "ear" before soaking a few minutes in salted water, draining, spreading on a cheesecloth-covered pan, and refrigerating to dry.

For firm-textured wood ear, slice and add directly to the dish being cooked. For a more tender texture, blanch first. Wood ears—with exceptions—are best considered as lively accents rather than single subjects. They do not lose their distinctive texture with long cooking, but soften slightly and absorb the surrounding liquid.


Beech/Clam Shell/Honshimeji

  • Sole goujonettes with Jura wine & mushrooms (Laurent Gras, executive chef, Peacock Alley, The Waldorf-Astoria, NYC): Prepare calf's foot jelly with chicken stock; strain. Slow-roast chicken legs with mirepoix to brown lightly; add garlic cloves and honshimeji and cook gently. Do not brown. Add Jura wine (Arbois), sole bones, and prepared stock. Simmer an hour and skim; strain. Stew sole trimmings with butter; add clarified stock and reduce. Add butter and strain. To serve, cook brown honshimeji caps in butter and a little Arbois. Boil more Arbois in pan; add Dover sole goujonettes. Add sauce and cook through. Plate with honshimeji and serve polenta with mascarpone and Parmesan on the side. ("The honshimeji adds great texture, but is very feminine and delicate and will not hurt the extraordinary wine.")

  • Loin of veal with fontina/country ham ravioli & Clam Shell mushrooms (Patrick O'Connell, chef/owner, The Inn at Little Washington, Washington, VA): Sear butt tenderloin in olive oil; finish in oven. Slice medallions and arrange interspersed with ravioli filled with mousse of country ham and fontina and white Clam Shells sautéed in a smoking hot pan. Sauce with reduction of veal and red wine seasoned lightly with herbs. ("Clam Shell's elfin looks are just right for this luxurious veal dish.")

  • Salmon baked in parchment (Anne Gingrass, chef/co-owner, Hawthorne Lane, San Francisco): On parchment, male a bed of halved baby carrots, leek slices, brown Clam Shell mushrooms, and celery slivers; top with salmon fillet and a pat of compound butter seasoned with tarragon, parsley, chervil, chives, lemon juice, zest, and vermouth. Seal and bake. ("With its looks and texture, the Clam Shell makes a great accent mushroom.")

Cinnamon Cap and Nameko

  • Cinnamon Cap "risotto" (Michael Otsuka, executive chef, Pacific Restaurant, San Francisco): Toast orzo in olive oil, then blanch to al dente. Finish with chicken broth, dry white wine, Parmesan, and duxelles of button mushrooms. To finish, stir in sautéed Cinnamon Caps finished with a little prosciutto fat.

  • Nameko in lobster broth (Pacific Restaurant): Chop lobster carcass and sauté in olive oil; deglaze with dry white wine and Cognac. Add chicken stock and lemon verbena; simmer briefly. Sauté nameko to release flavor, then strain lobster stock over. Finish with small, cooked foie gras cubes.


  • Huitlacoche crêpes, gratinéed (Josefina Howard, chef/owner, Rosa Mexicano, NYC): Sauté chopped onion and garlic in butter and olive oil until translucent; add huitlacoche, serrano chile, and salt; cook until liquid evaporates. Add crème fraîche and epazote. Spoon onto crêpes; roll. Set two on each plate; top with mascarpone and Manchego cheese. Glaze under heat. Top with epazote. (These other huitlacoche dishes are in Howard's repertoire: skewered poblano chiles and scallops on huitlacoche cream sauce; huitlacoche ravioli in poblano cream; huitlacoche cream soup with epazote; fried chicken breasts filled with huitlacoche; huitlacoche ice cream.)

  • Huitlacoche mashed potatoes (Richard Sandoval, chef/owner, Maya, NYC): Sauté onion until translucent. Add huitlacoche, serrano chile, and cilantro; cook briefly. At service, combine sieved, boiled potatoes with butter, milk, and seasoning; heat, then add huitlacoche. Serve with crisp-crusted fish.

  • Grilled corn soup with huitlacoche dumplings & vinaigrette (Maya): Puree husk-grilled corn kernels with cream; thin with stock. Prepare filling of sautéed onions, huitlacoche, epazote, and roasted chile de árbol; seal in wonton skins and poach. Set ravioli in soup and drizzle with seasoned vinaigrette of raw huitlacoche pureed with lemon juice, Sherry vinegar, and olive oil.

  • Tamales de huitlacoche (The Food and Life of Oaxaca by Zarela Martinez, Macmillan, NY, 1997): Prepare dough of coarse-ground fresh masa, chicken stock, and lard. Sauté chopped onion and garlic; add grilled, peeled, and diced poblano chiles, then huitlacoche, epazote, and salt. Cook gently for five minutes; cool. Stir in Oaxacan string cheese or shredded cheddar. Spread masa soaked corn husks, top with huitlacoche mixture, fold, and steam.

Oyster Mushrooms

  • Oyster mushrooms with an "aroma boost" (Hawthorne Lane): Sauté shallots and oyster mushrooms in butter and oil with broken cinnamon sticks. When browned, add seasoning, parsley, lemon juice, and zest. Let flavors marry off-heat. Serve at room temperature.

  • Blue oyster consommé (Jacky Robert, dining room chef, Maison Robert, Boston): Chop stems and boil with water, tarragon, parsley stems, and a hint of rosemary. Strain and clarify with tomato, carrot, celery, and egg white. Thicken with a bit of potato starch. Sauté blue oyster caps and halved white trumpets in a drop of olive oil with a touch of garlic. Place in a soup bowl. At table, pour in consommé; top with herbs.

  • Clear broth with mushrooms (John Wabeck, chef de cuisine, Restaurant Nora, Washington, D.C.): Prepare flavorful dashi and add blue oysters; simmer until tender. Add cubes of silken tofu, chopped scallion, sake, soy, and mirin to taste ("Nothing else; they get lost if mixed with other mushrooms or many ingredients").

  • Twice-sautéed king oysters (Pacific Restaurant): Tear mushrooms apart lengthwise into long strips. Sauté in olive oil; deglaze with dry white wine. Add vegetable broth; simmer gently until well cooked. Drain and blot dry. To serve, sauté until golden. ("This special technique brings out the earthiness in the mild mushrooms.")

  • Salad of wild mushrooms à la grecque with potatoes (Kenneth Oringer, executive chef, Clío, The Eliot Hotel, Boston): Slice king oysters into thick lengthwise cuts. Toss with hazelnut and olive oils and seasoning; roast in a bot oven. Cook fingerling potatoes with vinegar and a bouquet garni in the water. Slice and toss with light aïoli; plate. Top with a spoonful of mixed wild mushrooms à la grecque and an artichoke heart cooked à la barigoule. Top with roasted warm king oysters.

  • Veal scallops with mushrooms (Beth Collins, chef de cuisine, Gabriel's, NYC): Slice whole king oyster mushrooms lengthwise. Lightly color garlic in oil; add mushrooms. Deglaze with Pinot Grigio; season. Simmer to evaporate alcohol and cook mushrooms well. Dredge veal scallops in seasoned flour. Brown in butter and oil on both sides; finish in oven. Remove; add mushrooms and liquid; reduce. Pour over veal.

  • Risotto of white trumpet mushrooms & baby shrimp (The Inn at Little Washington): Prepare stock from sautéed oyster mushroom stems, chicken stock, and herbs. Prepare risotto base with onions, sautéed white trumpets, rice, and broth. When three-quarters cooked, spread on sheet pan and cool quickly. Heat risotto portions to order with hot stock and stir in very small raw shrimp. Sauté more whole trumpets to serve on top. Serve as an appetizer with confetti of Virginia country ham.

  • Gratin Normand (Maison Robert): Sauté shallots in butter, then add whole white trumpets. Add cream, bring to a boil, then strain. Reduce; season with cayenne and nutmeg. Mix reserved trumpets with blanched spinach and artichoke hearts. Fold in cream sauce, spread in pan, top with Parmesan, and heat under a salamander. ("White trumpets are best for soups, veloutés, and other pale, creamy dishes.")

Pompon Blanc

  • Pompon Blanc salad (Pacific Restaurant): Sauté slices in a nonstick skillet with a bare slick of fat just to color, not to cook through. ("The problem with these pretty mushrooms is they soak up so much fat.") Toss with roasted fingerling potatoes and frisée and dress with a light vinaigrette, such as Champagne vinegar, grapeseed oil, and a touch of olive oil.

  • Mushrooms in lobster broth (Randell Kliewer, executive chef, Glissandi, The Resort at Squaw Creek, Olympic Valley, CA): Season Pompon Blanc and place dry on sheet pan in a high oven (to avoid any fat changing the mushroom flavor unfavorably). Bake just until the edges color, but not until soft within; cut into slices. Sauté nameko caps quickly. Stir both unto clarified lobster broth infused with saffron and tomato.

  • Roasted Pompon Blanc with lobster gnocchi (Mark Franz, executive chef, Farallon, San Francisco): Brush Pompon with olive oil; season. Roast in a moderate oven until slightly crisped outside. Set on gnocchi studded with lobster bits and tarragon and spoon light shellfish sauce all over.

Wood Ear/Cloud Ear/Tree Ear

  • Wood ear mushroom velouté with pink peppercorn dust (Gary Palm, executive chef, Mission Inn, Riverside, CA): Sauté shallots and garlic in butter; add sliced wood ears. Deglaze with white wine; reduce by half. Add chicken stock and bouquet garni; reduce by half. Add cream and reduce by one-third. Remove bouquet and puree with a bar mixer. Season; add lemon juice. Plate and garnish with pink peppercorns pressed through a sieve and julienned wood ear. ("They have a distinct light taste and texture that remain special, even pureed.")

  • Tomato & onion tartlet with mushrooms (Mission Inn): Prepare confit by combining tomatoes and onions in a hotel pan with olive oil, bay leaves, and pepper. Cover with plastic wrap, then foil (the wrap seals, sticking to foil); bake in low oven for two hours. Cool, then drain. Add julienned, sautéed wood ear. To order, spread filling in tartlet mold lined with pâte salée. Bake until brown.

  • Wood ear garnish (Francesco Martorello, chef de cuisine, Brasserie Perrier, Philadelphia): Julienne fresh wood ears, toss with a little light soy, and marinate for an hour or so. Sauté in a hot iron pan in peanut oil to just crispen. Serve as a garnish to scallops or tucked into a spring roll with chicken and cilantro. ("Wood ears are truly a great value for the price. They have an amazing texture and look, and cost next to nothing.")

  • Soup of favas & wood ears (Clío): Blanch favas; peel skins. Combine with shallots sweated with lemon thyme; puree with vegetable stock. Sauté julienned wood ears in olive oil with garlic, shallot, lemon thyme, chervil, parsley, and tarragon; deglaze with mushroom stock. Mound wood ear in a shallow bowl; surround with pale fava puree. Slice spring truffle over this.

Musing About Raw Mushrooms

Think twice before you buy mushrooms on the basis of eye appeal alone. Shape and color rarely survive cooking. Some growers recommend serving mushrooms raw to preserve their form and hue. Think twice about this, too. If a taste doesn't explain, listen to two experts:

Malcolm Clark, president of Gourmet Mushrooms, biologist, and 25-year veteran of the specialty mushroom business, states emphatically: "We do not recommend that people eat cultivated mushrooms raw. They taste terrible—with the possible exception of shiitake—and can cause indigestion."

Annette Simonson, laboratory director of Northwest Mycological Consultants in Corvallis, Oregon, elaborates: "There are far more reasons to eat mushrooms cooked than raw—especially if you're in the restaurant business. First, raw mushrooms may contain natural toxins or compounds that interfere with digestion. Some customers may be sensitive to these. Second, sufficient cooking will kill bacteria that can grow, even on cultivated mushrooms. In addition, heating helps break down the tough fungal cell walls, increasing flavor and digestibility."