Winter truffle

What it is

The winter truffle is the fruiting body of an underground fungus that grows in partnership with tree roots. It is known as the Muscat truffle, and in some Italian and French market usage as the winter black truffle, a name it shares with the Périgord truffle, Tuber melanosporum. Its flesh is dark and its smell is strong and musky, with a peaty note. Those qualities are close to those of the Périgord truffle, but less intense.

Compared with the Périgord truffle the winter truffle is usually described as smaller, about the size of a walnut against the larger, sometimes apple-sized Périgord. Its surface has flat, angular warts rather than the raised, tightly packed warts of the Périgord. Those characters overlap enough that field identification alone is unreliable; the catalogue asks that the two species be kept apart in records.

Names and the cryptic species problem

The species was published by Vittadini in 1831 and placed in the Melanosporum clade. The name brumale, with its link to winter, and the name Muscat truffle, which refers to the aroma, are both in use. A musky form has been recognised as a variety, Tuber brumale var. moschatum, sometimes called the musky truffle.

The most important complication is that specimens called T. brumale do not all belong to one species. Multilocus phylogenetic work shows that the material given that name contains two species, and related taxa named T. cryptobrumale and T. petrophilum are recognised with a further proposed species, T. thracicum. Older market and literature records of winter truffle may therefore refer to a mixture, and a record that names only the common name should not be assumed to fix the species.

Where it grows

The species is native to southern Europe. It is a mycorrhizal truffle, living with tree roots in the soil and fruiting underground. Sources differ on its ecology. Some describe it as a weedy invader of Périgord truffle orchards. Others note that it is already present in the soils of many truffle orchards, and that the relation between the two species is more complex than an invasion.

A 1993 study cited by the encyclopedia examined how T. melanosporum competes with other ectomycorrhizal fungi under different irrigation regimes. That work concerns the Périgord truffle and does not by itself describe the winter truffle's habitat.

Use in cooking

The winter truffle is valued for its aroma in dishes where heat is used. The Périgord truffle loses part of its aroma when cooked, and it is usually shaved over a finished dish. The winter truffle keeps more of its character under heat, which is why the food industry uses it in sauces, pâtés and other cooked products.

Because it is cheaper than the Périgord truffle, it is also used where a truffle flavour is wanted in larger quantity, as the sources' comparison of price and use suggests.

Market and substitution

The species is sold at about a third to a half of the price of Périgord truffles, according to one dealer's comparison. Sellers sometimes market it under names that also belong to the Périgord truffle, so the label, the species and the price should be checked together.

The catalogue requires records to separate T. brumale from T. melanosporum in ingredient and provenance records, so a recipe line that says only truffle does not establish which species was used.

Notes

Open points: the field characters that reliably separate the cryptic species, the current names of the species that have been called winter truffle, and the historical record of how the truffle was traded before the modern market are not settled by the sources reviewed here.