Truffles are found in almost every forest in the world. We first discovered it in Quebec in the 1980s. And since then, the enthusiasm for this underground mushroom with its unique aromatic properties and a favorite among chefs has been so great that we have even started growing it.
To date, about fifteen species have been identified in Quebec, at least five of which have good taste characteristics. Several of these species were discovered by forest biologist Véronique Cloutier during her master’s and doctoral studies at the University of Laval.
Since these subterranean fungi transmit their spores through the small mammals that eat them, Ms. Cloutier attracted these animals by placing seeds and cedar shingles impregnated with the scent of truffles at the base of the trees. She then collected the droppings that the voles and flying squirrels had left behind after eating the seeds and truffles. She then carried out a genomic analysis of these excrements (the DNA present in these excrements), which allowed her to find out what types of underground fungi are present in this forest. Finally, she returned to the exact places where she had collected the excrements to take samples of these fungi, whose macroscopic and microscopic appearance she then examined.
In this way, she discovered several native species of truffles, some of which were completely unknown because they did not correspond to “any of the world references at macroscopic, microscopic or DNA levels.” She even named a tuber pichei.
These different types of truffles look like chocolate truffles but are smaller. In Quebec we find white, black, violet, lilac and many cinnamon-colored specimens. The most famous and interesting of them at the moment is the Appalachian truffle, scientific name Tuber canaliculatum, which is purple. This species was selected for truffle cultivation, which is currently practiced in eastern Quebec.
Truffles live in symbiosis with various species of conifers and deciduous trees, with the exception of maples, which form symbiotic associations with endomycorrhizal fungi rather than ectomycorrhizal fungi like truffles.
Ectomycorrhizal fungi such as truffles are macroscopic and grow between root cells. On the other hand, endomycorrhizal fungi – which we spread as fertilizer in our gardens – are microscopic and penetrate the root cells, explains Ms. Cloutier.
The truffle is mainly composed of a sporophore, the organ that contains the spores that form the fleshy part of the mushroom, that is, the part that we eat. This also includes roots called hyphae, which appear in the form of filaments. The root network formed by all hyphae is called mycelium.
In this symbiotic relationship that the truffle maintains with a tree, it supplies it with minerals that, thanks to its mycelium, it can absorb much further and faster than the tree’s roots can. “In fact, hyphae have a much larger surface area to volume ratio than tree roots and they grow much faster, giving them an advantage over tree roots. In addition, waterlogging of the hyphae can occur. They therefore represent a water reservoir that the tree can use in the event of a drought,” explains Véronique Cloutier.
The tree supplies the truffles with sugar that it produces during photosynthesis. “From August it gives them much more because the sugar it produces from that point on is no longer used for leaf formation. The tree then sends them to its underground parts and especially to the fungi associated with its roots, and not to its above-ground parts, which it no longer develops. For this reason, most mushrooms appear in autumn,” emphasizes the mushroom specialist.
How do we harvest truffles? In the forest we gently clear at the foot of the trees, where we find several holes dug by small mammals. “These holes mean that these small mammals were searching for or transporting something underground. When they wanted to carry something, we found cones, pine cones, hazelnuts or oak acorns that they had hidden. If they were looking for something, we would probably find truffles. But they will probably have taken a ripe specimen and left unripe ones,” specifies Ms. Cloutier.
Humans generally cannot distinguish between ripe and unripe truffles with the naked eye. “You can tell by looking at the spores, but if we do this manipulation we have to break down the truffle and then we can no longer sell it to chefs,” she says.
Ripe truffles give off a stronger smell that animals can detect. Traditionally, sows were used because truffles give off a scent of male pig pheromones that attracts them. But we switched to dogs because the old truffle farmers had their fingers cut off when they tried to pull the truffles out of the sows’ mouths. “It’s easier with dogs. “The dog is often more interested in pleasing us and receiving pets or treats as a reward than in finding and eating the truffles,” she says.
However, unlike sows, dogs require training. Training a good dog usually takes about two months. “We choose dogs that have good noses. The Lagotto Romagnolo is a breed specifically selected for the proof of truffles,” explains Jérôme Quirion, co-founder and co-owner of Truffes Québec.
There are dogs that dig up the truffle, others simply paw at the spot where they are buried, and others, like Taouk, Jérôme Quirion’s Australian Shepherd, sit and watch their master while waiting for a reward. It all depends on how the dogs were trained.