Truffles are found in almost every forest in the world. In Quebec, we discovered it for the first time in the 1980s. And since then, the craze for this underground mushroom with its unique aromatic properties and popular with chefs has grown to the point where we have even started to cultivate it.
To date, around fifteen species have been identified in Quebec, at least five of which have good taste properties. Several of these species were discovered by forest biologist Véronique Cloutier during her master’s and doctoral studies at Laval University.
As these underground fungi transmit their spores via the small mammals that eat them, Mme Cloutier attracted these animals by placing seeds and cedar shingles impregnated with the scent of truffles at the foot of the trees. She then collected the droppings that the voles and flying squirrels had left behind after eating the seeds and truffles. Then, she carried out a genomic analysis of these excrement (of the DNA present in these excrement), which allowed her to know which species of underground fungi were present in this forest. Finally, she returned to the precise locations where she had collected the excrement to take samples of these fungi, whose macroscopic and microscopic appearance she then studied.
This is how she uncovered several indigenous species of truffles, some of which were completely unknown, because they did not correspond “to any of the world references at the macroscopic, microscopic or DNA level”. She even named one Tuber pichei.
These different species of truffles look like chocolate truffles, but smaller. In Quebec, we find white, black, purple, lilac and many cinnamon-colored ones. For the moment, the best known and most interesting of them is the Appalachian truffle, scientifically named Tuber canaliculatum, which is purple. This is the species that was chosen for truffle farming 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 establish symbiotic associations with endomycorrhizal fungi rather than ectomycorrhizal fungi like truffles.
Ectomycorrhizal fungi, such as truffle, are macroscopic and grow between root cells. On the other hand, endomycorrhizal fungi – which we spread in our gardens as fertilizer – are microscopic and penetrate the root cells, explains M.me Cloutier.
The truffle is mainly composed of a sporophore, the organ which contains the spores, which constitutes the fleshy part of the mushroom, i.e. the part that we eat. It also includes roots, called hyphae, which appear in the form of filaments. The root network formed by all the hyphae is called the mycelium.
In this symbiotic relationship that the truffle maintains with a tree, it provides the latter with minerals that it will draw much further and more quickly, thanks to its mycelium, than the roots of the tree can do. “Hyphae actually have a much greater surface-to-volume ratio than tree roots and they grow much faster, giving them an advantage over tree roots. And what’s more, the hyphae can become waterlogged. They thus constitute a water reservoir which can be used by the tree in the event of drought,” explains Véronique Cloutier.
The tree provides the truffles with sugars, which it generates during photosynthesis. “It provides them with much more from August onwards, because the sugars it produces from that time onwards are no longer used to create foliage. The tree then sends them into its underground parts, and in particular to the fungi which are associated with its roots, rather than into its aerial parts which it no longer develops. This is why the majority of mushrooms come out in the fall,” underlines the mushroom specialist.
Harvest
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 went to look for or carry something underground. If they went to carry something, we will find softwood cones, pine cones, hazelnuts or oak acorns that they have hidden. If they went looking for something, we’d probably find truffles. But they will probably have taken a mature specimen and left immature ones,” says M.me Cloutier.
Humans generally cannot differentiate between mature and immature truffles with the naked eye. “It is possible to know by looking at the spores, but if we do this manipulation, we have to dissect the truffle and then we can no longer sell it to chefs,” she says.
Mature truffles will release a stronger odor that animals can detect. Traditionally, sows were used because truffles emit an odor of male pig pheromones which attracts them. But we changed to dogs because the old truffle farmers had their fingers cut off when they tried to pull the truffles from the sows’ mouths. “It’s easier with dogs. The dog is often more interested in pleasing us and receiving petting or treats as a reward than in finding and eating the truffles,” she says.
However, dogs must be trained, unlike sows. About two months are generally required to train a good dog. “We choose dogs that have a good nose. The Lagotto Romagnolo is a breed that was selected specifically to detect truffles,” explains Jérôme Quirion, co-founder and co-owner of Truffes Québec.
There are dogs who will dig up the truffle, others will simply paw at the place where they are buried, still 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.