What are truffles?

Truffles vary in size and shape. They typically range in size from that of a small nut to the size of a tennis ball and appear rounded with a knobbly surface. The interior has a distinctive marbled pattern.

Mycorrhiza Basics

Truffles are the edible fruiting bodies of a type of subterranean fungus known as a Mycorrhiza (“root fungus”), which form symbiotic relationships with a host tree.

Colonised Oak root tip

Colonised Oak root tip

The truffle coats the tips of the tree roots to form mycorrhiza which act as an extension of the tree's root system. The tree provides the truffle with a source of photosynthesised carbohydrates, and in return the fine, thread-like filaments (mycelia) of the truffle, extract and trade soil minerals and nutrients which would normally be unavailable to the tree.
Thus the mycorrhiza is able to increase the effectiveness of the trees roots, enabling the tree to grow in soils which would normally be too nutrient deficient to support them.

Culinary Uses

Truffles have a pungent aroma that can be loosely described as of ‘fresh earth’ and sweet mushrooms. Throughout history people have constantly failed to adequately describe the aroma and flavour of a premium truffle, contributing to the mystique of this exotic fungi. Their taste can permeate and enhance many foods such as soups, dips and patès, salads, sauces, dressings, omelettes and main meals. The irresistable allure of their unique aroma, flavour and taste accounts for their gourmet status, and demand by consumers, and makes them a highly valued ingredient.

Truffle Varieties

There are many types of truffles used for culinary purposes. The main truffle types are:
• French Black or Périgord truffle (Tuber melanosporum) named after the Périgord region of France
• The Burgundy or summer truffle (Tuber aestivum/uncinatum) from Central Europe, Turkey and North Africa.
• The Bianchetto (little white) truffle, (Tuber borchii) from Tuscany
• The Chinese truffle (Tuber sinense, Tuber indicum and Tuber himalayense) from Asia.

• and finally, regarded as the ultimate truffle by some, The Alba White Truffle, (Tuber magnatum) from the Piedmont region of Italy) Unfortunately, no cultivation of this truffle has been successful to date.

HOST TREES

The famous, highly prized, French Black Truffle is botanically named Tuber melanosporum and lives on several host species of Oaks and Hazel trees. The most commonly used tree species are as follows;

  • Quercus robur -English Oak
    Deciduous tree growing to about 20 metres. However, in a Truffière their height is much reduced by competition and pruning
  • Quercus ilex -Holm Oak, Holly Oak, Evergreen Oak
    Evergreen tree growing to about 15 metres
  • Quercus suber -Cork Oak
    Evergreen tree growing to about 15 metres
  • Corylus avellana -Hazel, Hazelnut
    Deciduous small tree branching from base growing to about 6 metres
  • Tuber aestivium is also grown on these species

Tuber borchii (Bianchetto aka "whitish truffle") is commercially grown on;

  • Pinus pinea (Stone pine famous for producing the edible pine nuts)
  • Corylus avellana -Hazel, Hazelnut
    Deciduous small tree branching from base growing to about 6 metres

LIFE CYCLE

The truffle fungus colonise the new root growth in spring and the developing mycelia spread out in the soil. From about January the tiny truffle sporophytes begin to develop (through a sexual process) and grow to maturity during the June, July and August period. Obviously there are specialised growing conditions (temperature, soil moisture, pH and nutrition) that need to be maintained to optimize the likelihood of truffle development.

It should be noted that the exact environmental triggers that affect truffle initiation and development and the process are not clearly understood. This is still the subject of much ongoing research and development.

Growers have reported harvesting Truffles at four years but more commonly production starts at around seven years after planting and then increases each year. Of course Oak trees are very long lived so with proper truffiére maintenance, truffles can continue to be harvested over many decades.