Frequently Asked Truffle Questions
What are truffles?
What is mycophagy?
What are mycorrhizae?
What is the role of truffles in ecosystems?
What are "True" vs. "False" truffles?
What are Ascomycetes and Basidiomycetes?
Are any truffles poisonous?
Where are truffles found?
How are truffles found?
Pigs vs. dogs?
Truffle maturity and the market
Truffle dog training?
Which truffles are the gourmet edibles?
What are pecan truffles?
How are truffles cooked?
Where can I buy truffles?
How do I store truffles?
I found a truffle. What is it?
How do I dry truffles?
What about truffle farming?
How do I find my local mycological club?
What are truffles?
Truffles are hypogeous (underground) versions of mushrooms. They don't form a prominent
stem and their spore-bearing surfaces are enclosed. They rely on animals eating them
(mycophagy) to distribute their spores, instead of air currents like mushrooms.
Truffles resemble small potatoes, and often between the size of a marble and a golf ball (see the photo gallery).
There are hundreds of different kinds of truffles, and while none are known to be poisonous,
only a few of them are considered to be delicacies by humans. Truffles (and mushrooms)
are only the "fruit" of the fungus (like an apple to an apple tree); the main perennial fungal body exists as a web of
filamentous hyphae in the soil.
All of the truffle fungi form mycorrhizae with the roots of trees, and are essential to
the trees' ability to acquire nutrients. The belowground fruiting habit of truffles is thought to be an
adaptation to forest fires or dry or frosty periods, in which aboveground mushrooms are more vulnerable.
Oregon State University Extension has published a nice overview of truffles available here,
"An Oregon Garden Guide to Truffles."
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What is mycophagy?
As most truffles never break the surface of the soil, they must rely on
animals to eat them and distribute the spores in their scats. The word "mycophagy" comes
from the Greek words "mykes" (fungus) + "phagein" (to eat).
Some animals, like the red-backed vole, eat truffles almost exclusively. In order to be located
by hungry critters, truffles have evolved strong scents that, as they mature, can be detected from a distance by a
suitably sensitive nose. Depending on the species of truffle, to humans these scents can be pungent,
fruity, unpleasant, or delectable.
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What is mycorrhizae?
Mycorrhizae is a symbiotic (mutually beneficial) association between some kinds of fungi and
plants. The word "mycorrhizae" comes from the Greek words "mykes" (fungus) + "rhiza" (root).
Fungal filaments (hyphae) are much more efficient at extracting water and nutrients
from the soil than root hairs - it has been reported that there are as much as 100 meters of fungal hyphae
in one teaspoon of healthy forest soil. The fungal hyphae not only permeate the soil, they penetrate the
root cells of plants and facilitate a nutrient exchange where the host plant gets needed nutrients from the soil via the fungi, and the fungi
(which cannot perform photosynthesis) get their needed sugars from the host plant. Many plants will
not grow well at all unless they have mycorrhizal fungi on their roots helping them get nutrients.
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What is the role of truffles in ecosystems?
Truffles (and mushrooms) are the "fruit" of underground webs of fungi. The fungi of all truffles
(and many mushrooms) are mycorrhizal. Mycorrhizae are essential in assisting
trees obtain nutrients and water from the soil - without mycorrhizae we would not have forests as we know them today.
Truffles are also an important part of the food chain via mycophagy.
For example, flying squirrels rely on truffles for food, and spotted owls rely on squirrels for food.
In turn, the fungi rely on the squirrels (and owls!) for spore distribution, the trees rely on the fungi for nutrient
acquisition, the fungi rely on the trees for energy (sugars from photosynthesis), and the owls and
squirrels rely on the trees for habitat.
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What are "True" vs. "False" truffles?
In Europe, the term "truffle" in the very strictest ("true") sense has historically only
referred to those hypogeous (belowground) fungi that were gourmet edibles,
primarily in the genus Tuber. Tubers are members of a larger grouping of
fungi called Ascomycetes. For some folks, only Tubers and their close relatives are
considered "true truffles" (all others being "false truffles"), and for other folks all hypogeous
Ascomycetes (irrespective of culinary qualities) are called "true truffles". However, there are many,
many other perfectly nice species of hypogeous fungi, both Ascomycetes and
Basidiomycetes, that are not particularly prized as food outside the
squirrel community. Nowadays many folks have discarded the "true truffle" and "false truffle"
distinctions for a more egalitarian nomenclature, and are quite comfortable simply calling all
hypogeous fungi TRUFFLES.
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What are Ascomycetes and Basidiomycetes?
Ascomycetes and Basidiomycetes are two major groups of fungi (like cats and dogs are two major groups of animals).
Unlike cats and dogs, the distinction between Ascomycetes and Basidiomycetes is based on
microscopic characteristics, namely the manner in which the
spores are produced. In Ascomycetes, the spores are produced inside of sock- or
sac-shaped structures called
asci. In Basidiomycetes, the spores are produced on prongs on the
outside of structures called basidia.
As a general rule, Ascomycetes tend to have a brittle texture
(such as Morels), and hypogeous (belowground) Ascomycetes
(eg. truffles) are frequently
- but not always - hollow (such as Genea). Basidiomycetes
are fleshier in texture (all gilled mushrooms
are Basidiomycetes), and the hypogeous Basidiomycetes tend to be squishy or spongy on the
inside (such as Zelleromyces).
This key may help in distinguishing "asco's" from "basid's".
There are two other groups: The Mucoromycetes form their spores individually on specialized "suspensor cells" and
contain one truffle-forming ectomycorrhizal genus, Endogone. The Glomeromycetes form their spores individually
or in clusters at the ends of hyphae. Only one genus in this group forms truffles, Glomus.
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Are any truffles poisonous?
No truffles are known to be poisonous to humans (but we don't know everything...). This non-toxicity seems sensible, considering
that truffles rely on small animals (via mycophagy) to distribute their spores. That said, ALWAYS
be absolutely sure of the identification of anything you are considering eating! Many poisonous Amanita
and Cortinarius mushrooms start out as
belowground "eggs" that can be dead-ringers for truffles at a glance. The Oregon white truffles that most folks
around here are interested in eating (Tuber gibbosum & T. oregonense
Back to top...Where are truffles found?
Truffles can potentially be found almost anywhere there are trees. Only a few families of trees (such as maples and cedars) do not associate with truffle-forming fungi. Truffles fruit throughout the fall, winter, and spring, depending on species and locality. They usually occur at the interface between the organic litter and the mineral soil, about one to six inches deep, but can emerge to the surface or be more than a foot deep. Evidence that small animals have been digging in an area recently is often a good indication that truffles may be about. For a detailed accounting of what kind of habitat a particular truffle species likes, and when it is likely to be found, see the Specific Habitats page.
Back to top...How are truffles found?
In North America, truffles are found by raking the organic litter away with a 4-tine garden rake. Find suitable habitat (most any forested area; see above) and gently peel back the litter layer (remember to replace the litter when you are done and try to leave the area as you found it). Look for things that look like little potatoes, often beige, yellowish, or reddish brown (see the photo gallery). If you find one it will be immediately apparent that it is not a dirt clod. Finding truffles takes a little luck and a lot of patience. Sometimes they just aren't there, but you never know until you look. In Europe, pigs and dogs have been used for centuries to help find truffles.
Back to top...Pigs vs. dogs?
The scents produced by truffles to encourage mycophagy sometimes attract animals that are larger than squirrels. Some truffles, including the gourmet edibles Italian perigord, French white, and Oregon white, produce a scent that mimics a male pig sex hormone. It is for this reason that female pigs have been used historically in Europe to help find truffles. More recently, dogs have become the preferred truffle hunting companion for several reasons, among them 1) Dogs can be trained to find, but not eat the truffles, and 2) Dogs are much easier to get into the back seat of a car.
Back to top...Truffle maturity and the market
In the United States, we have not advanced to the point of using trained animals to help find truffles. This is unfortunate not only from an efficiency standpoint, but also a market reputation standpoint. The reason for this is that truffles only develop the aroma that attracts animals and excites chefs when they are fully mature. Thus, pigs and dogs will only indicate where mature truffles are. In North America where we humans (with our lousy noses) rake indiscriminately for truffles, we frequently get as many immature specimens as mature ones. Commercial collectors often have incentive to sell all the truffles they find, whether they are mature or not. Immature truffles have little culinary value, as they have not yet developed the pungent aromas that chefs seek. The frequent presence of immature specimens in commercially available Oregon white truffles has diminished their reputation and value on the world market compared to their European counterparts.
Back to top...Truffle dog training?
NATS offers occasional truffle dog training seminars in Corvallis, Oregon. Contact Marilyn Hinds for information. Below are some dog trainers who offer specialty courses in canine trufflehunting, in no particular order:
Pacific Truffle Dogs offers truffle dog training courses in the Portland area.
Umami Truffle Dogs offers truffle dog training courses in Veneta, west of Eugene.
NW Truffle Dogs offers truffle dog training courses in the Portland area.
Trifecta Training offers truffle dog training courses in the Eugene area.
The Truffle Dog Company offers truffle dog training courses in the Seattle area.
Pasqual Sricco offers truffle dog training courses in New Jersey, and sells truffle dog training videotapes.
The general principal is to start when the dog is young, and
get them used to the scent of truffles by having them fetch a sock with mature truffles inside,
and gradually work up to finding the hidden, then buried sock. Some folks have used a pungent
cheese (like limburger) as a surrogate for mature truffles.
Links to accounts of truffle dog training are below:
Truffle dog training in Italy
A history of training poodles
Hunting truffles with dogs in France
Hunting truffles with dogs in Alba
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Which truffles are the gourmet edibles?
Oregon white truffle (Tuber oregonense and T. gibbosum)
Reasonably common in the Pacific Northwest from the west side of the Cascade mountains to the coast from British Columbia to northern California.
Tuber oregonense is generally found from October through February. Its exterior perideum is
whitish when young, developing orangish-brown tints as it matures, and finally becoming orangish-brown overall. Microscopically,
it has a perideum of interwoven hyphae. Tuber gibbosum is usually found from February through June. Its exterior perideum
begins whitish and becomes pale olive-brown as it matures. Microscopically the perideum is of inflated cells.
In both species, the texture is quite firm (not spongy), and the interior is white when immature becoming a marbled
smokey brown as it matures. Both species seem to prefer young (15-40 year-old) Douglas-fir plantations. By February, most
of the Tuber oregonense should be pretty mature and the T. gibbosum
will just be getting started. Tom Volk has a nice
Oregon white truffle website. You can also read more about both Oregon white and black truffles in
this article.
Oregon brown truffle (Kalapuya brunnea)
The Oregon brown truffle was discovered by NATS members in the early 1990's and formally described in 2010. It grows in younger Douglas-fir forests in the Oregon Coast Range and western foothills of the
Cascades. It has a reddish-brown exterior and a greyish mottled interior. When mature the odor can be quite garlicky.
Oregon black truffle (Leucangium carthusianum, formerly Picoa carthusiana)
Less common than Oregon white truffles, Oregon blacks are larger (golf-ball to baseball size), and are often much deeper in
the soil than Oregon whites (commonly 4-10" deep). They are very dark inside and out, and have
a very pungent, earthy odor when ripe. Some equate the aroma to a strange mix of pineapple, port,
mushrooms, rich soil, and chocolate. Looking like irregular lumps of coal, with white-veined flesh,
the Oregon black truffle has a texture of moist Parmesan and ground almonds.
French black (Perigord) truffle (Tuber melanosporum)
Native to the oak forests of the Perigord region of central and southwest France, it is now widely cultivated in
Spain, Australia, and the United States. The black perigord
is among the most valuable of truffles at up to $1000/pound. It has a blue-black exterior when
fresh, fading to brown-black with age and a pungent, earthy odor.
Italian white (Piedmont) truffle (Tuber magnatum)
Considered by some (mostly the French) to be second best to the French black truffles, its cost can exceed that of the perigord.
It is native to the foothills and mountains of northern and central Italy and southern Yugoslavia.
They grow in conjuction with oak, hazel, poplar, and beech trees. The flesh is solid, light-coloured, and very brittle; it is not unheard of for a
fresh truffle to shatter if dropped on the floor. Large specimens can weigh as much as a pound,
but most are the size of large walnuts. The white truffle is slightly more perishable than its
darker cousins, and the flavour and aroma diminishes within a week or two after harvest. The
white truffle has a distinctive pepper edge and is often eaten raw. The skin is a dirty beige
when fresh, turning a darker brown with age. More information can be found at
this website.
Burgundy, or Summer truffle (Tuber aestivum, formerly Tuber uncinatum)
Native to France, Italy, and Spain, the summer truffles are usually at their best in July,
but can be found from May to October. They have a black exterior and off-white interior, and a
relatively light scent. This truffle has been established on plantations in Sweden and New Zealand.
Tuscan truffle (Tuber borchii, formerly Tuber albidum)
Similar to the Italian white truffle in appearance, having a chestnut to muddy tan exterior and
a softish interior equally divided between chocolate brown and white. The flavor can be distinctly garlicky.
Pecan (Texas) truffle (Tuber lyonii, formerly Tuber texense)
Pecan truffles (also called Texas truffles) are found from New Mexico to the gulf coast and eastern seaboard to the great lakes
and eastern Canada. It is not limited to areas with pecan trees, but was named based on the habitat in which it was discovered.
More information can be found at this
University of Georgia website.
Click here for a story about
Pecan truffles from the Hilton Head Island-Bluffton Island Packet, and click here
for a story about Pecan truffles from the New York Times.
Chinese truffles (Tuber sinense, Tuber indicum, and Tuber himalayense)
These are three distinct species found in southwest China, but pickers tend to lump them together as
Chinese truffles. This is unfortunate since the flavor and quality vary from one species to
another. First marketed in France in 1994, these truffles are now found in American restaurants
at fairly reasonable prices, but their flavor and aroma do not come close to that of the French
truffles, perhaps for the same reasons as Oregon white truffles (too many immature specimens). T. indicum
is recognizable by its brown interior and very fine white veins. T. sinense has a dark
brown interior with large ivory veins, and is said to be chewy and oily with a bitter aftertaste.
Desert truffles (Terfezia boudieri, Terfezia pfielii, Terfezia claveryi, and others)
Native to northern Africa and the Middle East, these truffles have been a staple for many nomadic tribes for
millenia. Sometimes called the Lightning Truffle, they often fruit shortly after thunderstorms wet the desert.
There is an account of desert truffle culture here.
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How are truffles cooked?
Truffles are generally used raw, or very lightly cooked, because the flavor compounds are highly volatile.
Truffles go very well with brie cheese (doesn't everything?). NATS has compiled a cookbook of truffle recipes, a few of
which are posted on the Recipes page. Below are some links to other truffle recipe websites:
The Mycological Society of San Francisco
The Cottage Kitchen
Truffes-de-Provence, with notes about storage
The Truffle Zone
Oregon White Truffles
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Where can I buy truffles?
There are tons of websites selling truffle-related products. Here are a few, selected for no particular
reason. NATS does not endorse or guarantee any of these sites! You might also try ebay...
Oregon Wild Edibles
MycoLogical Natural Products
Tartufi Unlimited
The Wine and Truffle Co.
Truffles USA
Gourmet Foodstore
Earthy Delights
Marky's Caviar
US Shops
How do I store truffles?
Truffles can be stored for several days in a paper bag (never in plastic!) in the refrigerator.
They can be frozen for several months in a glass jar. They can be immersed in olive oil, and the
oil will absorb the flavor, however shelf life at room temperature is limited without pasteurization.
Some folks store truffles in dry white rice, but this is not recommended as the rice will tend to draw the moisture and aroma away
from the truffles, diffusing and diluting the aroma. Ideally, truffles should be used as fresh
as possible, unless you are in the enviable situation of having too many!
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I found a truffle. What is it?
What? You don't have your very own copy of the NATS Field Guide to Selected North American Truffles
and Truffle-like Fungi? You can get one here!
Alternatively, you can mail specimens to the Trufflemaster for identification. Truffles should be dried thoroughly before
mailing (see below).
For more infomation on sending truffles for identification click here. Include your email address, collection
location and habitat data, and any notes about unique fresh characteristics (odor, staining reactions, etc.).
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How do I dry truffles?
Truffles should be dried before sending to the Trufflemaster for identification, but not if you intend to eat them. Fresh truffles
sent through the mail often arrive as an unrecognizable furry odiferous lump - not a good thing! Ideally, truffles to be mailed
for identification should be dried on a regular food dehydrator. If you don't have a dehydrator, leave them in the fridge in a
loosely closed paper bag for about 3 days, this will dry them quite well (Caution: This may impart a truffle flavor all other
foods in the refrigerator!). Truffles dry a lot faster if they are cut in half first. For more information on sending truffles
for identification click here.
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What about truffle farming?
Businesses that sell trees inoculated with truffle mycorrhiza can easily be found on the internet. Results are not
guaranteed and can take years. It is a good idea to get sample trees assessed for root colonization by an independent
lab (such as MycoRoots).
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How do I find my local mycological club?
Go to the excellent Club Directory on
the NAMA website!
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