line_gbg70.gif (2214 bytes)

Truffles
Fungi
line_gbg70.gif (2214 bytes)

Truffles: History and General Information

The truffle is a subterranean fungus that lives in symbiosis with the roots of trees. It resembles a tuber and has an internal fleshy part or pulp ("gleba") and rind ("peridium"). Truffles contain a high percentage of water, fibres and mineral salts absorbed from the soil through the roots of the tree with which they live in mutually beneficial association.

They are classified in various species and the most renowned for gastronomic purposes are:

  • Tuber magnatu pico - the white truffle of Alba
  • Tuber melanosporum Vitt. - the prized black truffle of Norcia, known to the French as the “truffe du Périgord”
  • Tuber aestivum Vitt. - the “scorzone” or Summer black truffle
  • Tuber uncinatum - the black truffle
  • Tuber borchii - the "bianchetto" truffle
  • Tuber brumale - the black musk truffle

There are some hundred varieties of truffles but there are only two more renowned and prized species: the white truffle of Alba ("Tuber magnatum pico") and the black truffle of Norcia ("Tuber melanosporum").

The latter, with an odour that is less intense but still appreciated by gourmets, is particularly abundant in Central Italy (especially in Umbria) and in France (in the Périgord region) but it is also found to a noteworthy extent in Piedmont.

The geographical diffusion of the white truffle is more complex. Piedmont is still its home and represents its ideal habitat on the hills on the Langhe and Monferrato.

There are regions such as the Marches (Acqualagna, S. Angelo in Vado), Umbria (Gubbio, Citta' di Castello), Tuscany (San Miniato), Romagna (Valle del Montone) with small areas in which white truffles can be found, including in Istria, with different characteristics in each area.

The trees that accept this “co-existence” with their roots more readily are the poplar, lime, oak, and willow.

The colour, flavour and odour of the truffles are determined by the specific characteristics of each tree. For example, truffles that grow close to oak trees have a more penetrating odour while those found close to limes will be lighter in colour and more fragrant.

The shape of the truffle depends on the type of soil. If the ground is soft, the truffle will be smooth and round whereas if the soil is compact, the truffle will be lumpy and knotty as it encounters greater difficulty in finding space for growth.

Although the conditions of the soil may be excellent as regards pH and humidity and the tree potentially suitable for the growth of truffles, not all trees are able promote their development. Truffle growers have been studying this particular phenomenon for many years with a view to the future production of truffles in woodland under the direct control of man and not tied simply to chance. This research has already produced satisfactory results as regards certain types of truffles (e.g. cultivation of the highly-valued black truffle) but, unfortunately, achievement of similar results in the production of the white truffle of Alba still remains a long way off. For the moment, it has been ascertained that these require soil with large pores with high level oxygenation, rich in calcium and with a good level of humidity also in the Summer period. However, even if these particular conditions are present, good results are not always achieved. Research continues but, for the moment, this precious fruit of the earth continues to be a fascinating jewel wrapped in an aura of magic. This state of affairs may continue for some time but we can still continue to enjoy the truffle and appreciate it as nature has created it.

The White Truffle - Tuber Magnatum Pico

Ecology and cultivation

The white truffle (Tuber magnatum Pico), also known at the Alba or Piedmont truffle, has a growing area limited to Italy - all over Piedmont in the Monferrato, Langhe and Roero districts and partly on the hills of Turin - but it is also found, to a much lesser extent in some areas of Central Italy, in South France and in some regions of ex-Yugoalavia, especially Istria.

The highly prized white truffle is considered to be the truffle par excellence because of its noteworthy commercial importance.

[The author of the major part of the following segment is Mattia Bencivenga, Department of Plant Biology, University of Perugia, Borgo Giugno 74, I-06121 Perugia, Italy]

It is harvested from October [or September in Istria] to December in particular ecological niches: deep soil, poor in course fragments, calcareous, sub-alkaline (pH > 7.6), sandy-loam, recent or actual flooding or land slide depositions, very soft, rich in interconnected macropores and with an apparent density between 1.1 and 1.2. Furthermore, they are completely shaded by one or two layers of vegetation and undergo minimal daily or seasonal temperature changes. They are able to maintain a sufficient moisture level so as to allow the development of a luxurious vegetation characterized primarily by the presence of Salicaceae, Fagaceae and Corylaceae. The amount harvested annually is a few hundred quintals and therefore, together with its high gastronomic value, explains the market price which oscillates between $500 and $3000 per kilogram. The cultivation of Tuber magnatum Pico has not yet given satisfactory production for reasons not well-known. It is important to note that the particular ecological requirements are not easy to create in the field. Furthermore, there is perplexity about the production of mycorrhized plants: the enzymatic and biomolecular analyses conducted on the root systems of plants artificially inoculated in the laboratory and under aseptic conditions with spores of Tuber magnatum do not show the presence of the mycorrhizae of this species but show the presence of mycorrhizae of Tuber borchii Vitt. On the other hand, plantings made with plants inoculated with Tuber borchii all gave good production of fruiting bodies of this species, while the plantings of the same age, made with plants inoculated with Tuber magnatum and well-mycorrhized, behaved in different ways. They did not produce, or produced some fruiting bodies of Tuber borchii and in some cases Tuber magnatum. This is an open problem that needs to be resolved. I maintain that the most important factor is ecological, in that, in suitable environments, optimum truffle beds have been obtained by only planting out cuttings of the symbiotic plants. It is of globular shape with many depressions on the rind that make it irregular. The outer surface is smooth and slightly velvety. Colour varies from pale ochre to dark cream, to greenish. The flesh or gleba is unmistakable and is white or greyish yellow with thin white veins. Its pleasantly fragrant aroma, different from the garlicky flavour of the other truffles, makes it unique. It lives in symbiosis with oaks, limes, poplars and willows and is seldom found together with other truffles. To grow and develop, the white truffle needs particular types of soil and equally particular climatic conditions. The soil must be soft and humid for most of the year, it must be rich in calcium and well ventilated. Obviously not all soils are able to guarantee these characteristics and it is these environmental factors that make the white truffle a rare and highly-prized fruit of the earth.

Where the prized white truffle is found

Gleba (above) and spore (below) of the Tuber magnatum pico.
Photos by © Gabriella Di Massimo.

It can be said that the prized white truffle grows in places where, year after year, external dynamic agents recreate a thin soft layer of soil that can be readily colonised by the fungus and in which good circulation of air is assured. This combination of factors is fairly rare in nature. Also, these conditions must occur in synchronism with the annual cycle of the fungus. For example, in the environment of the rocks of the Roero district (bordering on the famous Langhe), the soft porous layer is created each year by the Autumn rains. These cause fast, localised flooding of the rivers of the valley bottom. The earthy material transported by the waters is then deposited quickly and chaotically along the banks creating highly porous soil structures connected to the outside. The next Spring, this layer, without any form of vegetation and rich in large pores and in communication with the outside, is rapidly colonised by the new mycorrhized roots and subsequently by the mycelium. If the climate is favourable in the Summer, such as to preserve the mycelium of the fungus and the highest possible number of fruit-bearing primordia, there will be a good production of the prized white truffle in the Autumn. This cycle must be renewed each year because the soil tends to harden and to lose its porosity as the spaces are filled by the fine material transported by the water, due to the effect of the driving rain and also compression of the roots of the grass species that colonise the soil subsequently.

It can generally be said that that the environments of the prized white truffle are the result of a strong morphological change in a calcareous ambient with a temperate rainy climate with fresh and humid Summers. Therefore, it is also possible to find natural truffle grounds along slopes characterised by small surface landslides (typical of the areas of San Miniato or along the entire Apennines from Emilia as far as the highest areas of Southern of Italy). In some cases, alternating freezing/thawing cycles recreate a sufficiently porous layer for development of the truffle (climate of the areas of the Mugello and Montefeltro). On other occasions, it may be created by unconscious action of man in the case of not excessively deep tilling of the land, tied possibly to soils consisting of stable materials that do not lose their porous structure and are able to withstand, more than others, compacting by rain, as in the case of the calcareous marls of the areas of Acqualagna and Piedmont. From what has been said above, it is easy to understand how the environments in which the white truffle grows appear, at first sight, to very different but the how they are in fact specific and similar if observed from the point of view of the truffle.

As it is a subterranean fungus with not very flexible biological requirements, it is the environment of the soil that must be assessed in its entirety. This is why, in the case of well mycorrhized plants, the truffle selects apparently different areas with however the three essential soil conditions in common for its reproduction.

See: Soils Which Produce the Truffle

The 1000-year-old history of an underground jewel

The scientific name of this subterranean fungus is Tuber magnatum pico, better known as the White truffle of Alba, from the name of the ancient city, Alba Pompeia, which also gave birth to the Roman Emperor Pertinax. This truffle, known in the local dialect as "trifola" and rated by all the experts as the very best, is found in a restricted hilly area of the “Langhe” and in part of the Monferrato district.

In ancient times, it was thought that the truffles derived from bolts of lightning that fell close to the trees. In actual fact, they grow spontaneously only under certain trees, in particular oaks, willows, limes, poplars and cherry trees.

According to the old truffle hunters of Langa and Monferrato: the white truffle will be ripe only at the third moon after the rains, starting from September: superstition or phases of the moon apart, it seems that the proverb is constantly confirmed. On the other hand, the world of the truffle hunter or trifulao as they are called in Piedmont is fraught with magic and mystery, also due to the fact that the dogs work well only during the night, even better if wrapped in mist that dampens sounds and confuses the outlines of things.

Truffle gatherers usually set off as twilight falls, mainly to avoid revealing the most suitable places to “competitors”. The world of the truffle has much in common with the hard life of the country...

Gathering truffles is an art based on an indivisible “duo”: man’s experience in identifying the most suitable trees and the infallible scent of his dog who, having identified the precise point, digs furiously to reveal the precious fragrant prize.

For centuries, the “tools of the trade” of the "trifolao" as truffle gatherers are known in Piedmont, have been a pair of tough, mud-proof boots, a stick,also useful for grubbing in brambles and shrubs, a small spade to dig around the truffle without damaging it, a jacket with lots of deep pockets to hold the truffles gathered and the pieces of bread usually bestowed on his faithful companion each time it finds a truffle.

See: La luna

Additional information:

From Donald Wyman. Wyman's Gardening Encyclopedia, 2nd Ed.,  MacMillan Publishing Co., New York,     Collier MacMillan Publishers, London (1986), p. 1127 Tartufi (truffles) - a sac fungi

The fruiting bodies of a fungus of the genus Tuber, a member of the Ascomycetes, the most important species being T. aestivum, considered by many an outstanding delicacy among mushrooms. They grow entirely under the soil surface, sometimes 12 inches below the surface. They are tuberlike, fleshy, fruiting bodies, 1-4 in. across, bluish black when moist but brown when dry, and covered with hard, ribbed and furrowed warts. They have a pleasant odor but since they grow beneath the surface they are difficult to find except for those who have had experience looking for them. France is probably the only country exporting them, but they are found in England, Italy, and other European  countries. Usually they grow in soil at the edge of woodlands, especially near groups of evergreen oaks   (Quercus liex and Q. coccifera) as well as near beeches (Fagus sylvatica).

In the past, animals have been trained to hunt for them.  In France, small dogs or poodles* have been used, and even pigs. Where abundant, men who have hunted them for some time can detect the faint odor and find them satisfactorily. Truffles have not proved easy to cultivate artificially and are not grown in America.**

From Geofrey Kibby. Mushrooms and Toadstools, Chartwell Books, Inc., New Jersey (1977), pg. 78-79: Truffle hunting

The photograph on the right shows a truffle hunter in the classic traditions of Europe, with truffle pig and mushroom basket to hand.  The pig's sensitive nose can detect truffles from a considerable distance and soon roots them out for his lucky owner. Indeed, the only difficulty is in beating the pig to the spot and preventing  him from eating all the find! Dogs are also used and can detect truffles at even greater distances than a pig, but their training is more difficult as dogs do not possess the passion for truffles that is inherent in the pig.

Sources:

  • http://www.albatartufi.com/
  • Ecology and cultivation of Tuber magnatum Pico - http://www-mykopat.slu.se/Newwebsite/mycorrhiza/edible/abstracts/bencivenga.html
  • As cited above.

Related links:

  • What are Truffles? - http://www.trueffel.ch/truffel.html
  • Tartufomania, Soils which Produce the Truffle - http://www.hesp.it/tartufomania/indexing.htm & http://www.hesp.it/tartufomania/articing.htm
  • Epicurious Profile: Truffles - http://food.epicurious.com/e_eating/e02_truffle/truffle.html
  • Dictionary - http://food.epicurious.com/run/fooddictionary/browse?entry_id=10658
  • Finding Truffles - http://www.herb.lsa.umich.edu/kidpage/truffind.htm
  • Alternative Truffle Hunting Methods - http://www.areacom.it/html/turista/tartufo/Numero1/testi-e/07metalt.html
  • Truffles: Fruit of the Desert - http://embassyofkuwait.com/truffles.htm
  • San Miniato: The Truffle Trail - http://chanoines.arttech-prod.fr/
  • Santa Margherita: Truffle Menu - http://www.smargherita.com/ricette_e/9810_4/menu.html
  • Tricks and Recipes - http://www.fme.asso.fr/domaine/arectruf.html and http://www.fme.asso.fr/domaine/abeurre.html
  • The Mushroom Grower's Newsletter: Truffle Recipes - http://home.cdsnet.net/~mycowrld/trufrec.html
  • Winter Ingredients: Truffles - http://food.epicurious.com/e_eating/e02_wintering/winterveges/truffles.html
  • Montana Truffles - http://www.wildrockies.org/Fungal-Jungal/truffle.htm
  • Truffles in New Zealand - http://www.gisborne.co.nz/truffle_dinner/truffles_in_nz.html
  • Media Release: Perigord Truffle - http://www.crop.cri.nz/news/mediarel/014PERIG.HTM
  • CuisineNet Cafe: The Trouble with Truffles - http://www.cuisinenet.com/cafe/another_adventure/1998/00004-2.shtml
  • Dogs Die Hunting Truffles - http://www.sltrib.com/97/nov/112197/nation_w/8476.htm

Main Menu


Created: Saturday, July 24, 1999; Last Updated: Wednesday, September 14, 2016
Copyright © 1998 IstriaNet.org, USA