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Tuber magnatum,Pico (1788) Meleth. bot. 79. the white truffle (Italian language: tartufo bianco d'Alba), is a species of truffle in the order Pezizales and family Tuberaceae. It is found in Southern Europe, The Balkans as well as Thailand.
White truffles have also been found in Croatia (Istria, Motovun forest along the Mirna river), in the Ticino and Geneva cantons of Switzerland, in south-east France, in Sicily, Hungary, Serbia, Slovenia (along the Dragonja and Rizana river), Greece, and in Thailand.Graziosi & al. 2022 (bibliography)Nakarin Suwannarach, Jaturong Kumla, Jomkwan Meerak & Saisamorn Lumyong. "Tuber magnatum in Thailand, a first report from Asia" (PDF), Mycotaxon, vol. 132, p. 635–642, July–September 2017Jun Niimi, Auréelie Deveau & Richard Splivallo. "Geographical-based variations in white truffle Tuber magnatum aroma is explained by quantitative differences in key volatile compounds", New Phytologist, 2021, vol. 230, p. 1623-1638.
In recent years, the search for truffles became very popular in Bosnia and Herzegovina. Especially abundant occurrence is recorded in the regions of Vlašić, Lisina and Kozara, and lately, after discovery of its presence, in the western part of the Herzegovina region, around the village of Služanj and the town of Čitluk.
The most common host plants cited in the literature are oaks, including associations with Mediterranean species ( Q. pubescens, Quercus cerris and Quercus ilex) and temperate species ( Quercus robur and Quercus petraea). The second most common host plant cited are poplars, mainly Populus alba (about 13%) but also Populus nigra, Populus tremula, P. canadensis and P. deltoides. Among willows, four species are listed: Salix caprea, Salix alba, salix purpurea and Salix apennina.
Less commonly, they are associated with five other species of host plants, each from different genera: Abies alba (conifer), Alnus cordata, Fagus sylvatica, Pyrus pyraster and Ulmus minor.
In the Balkans and Pannonia regions, its soils contain 20% clay or more (in opposition to Tuber melanosporum which needs well-drained soils with higher sand/silt content); but in the Apennines and maybe also in Istria, the silt content dominates (45%) at the expense of clay (< 20%).
Much depends on the vertical repartition of mineral and organic matter, determined during initial soil formation due to flooding. The sediments are typically high in carbonates (15%) in Italy and Istria, but only around 10% at Hungarian and Balkan sites. Samely, organic matter content in Italy is three times higher (about 14%) than that of WT sites in the Balkans (4.5%). Nitrogen content is relatively low (0.19–0.26%). This gives a C/N ratio of around 7 at Italian sites - which corresponds to relatively slow decomposition rates - and a higher C/N ratio in the Hungarian and Balkan lowlands - exposed to very regular flooding, inducing faster decomposition rates and elevated microbial activity in the uppermost soil layer.
Associated microbial and fungal communities are poorly known at this stage (2018) and further studies in that direction are recommended.
Seasonality (the amplitude between summer and winter) seems to also play an important role. It thrives best at sites with ~ 13 °C per year, with average annual temperature ranges of ~ 12 °C in Mar–May, 22 °C in Jun–Aug, 14 °C in Sep–Nov, and 5 °C for Dec–Feb. The warmest mean air temperature for WT growth in Jun–Aug is 24.3 °C (99th percentile), about four degrees above the physiological optimum for mycelial development in soil; temperatures in excess of this limit reduce the amount of mycelium in the topsoil (on about 10 cm); this may explain why T. magnatum develops extra-radical mycelium in soil horizons below 30 cm.
In November 1999, what was then the largest truffle in the world was found near Buje, Croatia. The truffle weighed and was entered into the Guinness Book of Records.
The record price paid for a single white truffle was set in December 2007, when Macau casino owner Stanley Ho paid $330,000 (£165,000) for a specimen weighing . One of the largest truffles found in decades, it was unearthed near Pisa, Italy, and sold at an auction held simultaneously in Macau, Hong Kong, and Florence. This record was then matched on November 27, 2010, when Ho again paid $330,000 for a pair of white truffles, including one weighing nearly a kilogram.
In December 2014, a white truffle weighing was unearthed in the region of Italy. It was auctioned by Sabatino Truffles at Sotheby's in New York. While some had expected it to sell for $1 million, it was sold for $61,000 to a Taiwanese buyer. In 2021, a white truffle from Piedmont weighing 830 g was sold for €103,000 at auction.
On the Asti market in 2012, more than 90% of the truffles did not come from Alba and about 75% of the white truffles supposedly from Piedmont came from other Italian regions. Tuber oligospermum, that grows well in Tunisia's dry sand and not deemed of any culinary value in Italy, is sold as T. magnatum. In some cases, scent is enhanced with such petroleum-based essence as bis(methylthio)methane which is harmful to human health. In 2017, Italy's financial police, the Guardia di Finanza, uncovered a €66 million tax fraud among truffle producers.Ryan Jacobs. "Inside the Exceptionally Shady World of Truffle Fraud", May 28, 2019, on eater.com.
Zinc content is an important differentiating trait: it was found to be twice as high in T. magnatum than in all the other truffle species so far tested. T. magnatum also assimilates/accumulates copper, potassium, sodium, phosphorus, and zinc more efficiently than these other species; on the other hand, Tuber brumale was more successful in assimilating/accumulating sulfur.
But carbon isotope signatures of the various truffle species cannot discriminate their geographical origins, because mycorrhizal fungi are enriched in 13C compared to their host trees (fungi receive up to 20% of the total carbon fixed by their host trees), and forest ecosystems are characterized by settings that are too complex to allow for such discrimination. For example, highly heterogenous Italian forest ecosystems with high fungal biodiversity showed both the lowest and the highest δ34S values in the truffle samples.
In 2017, a new Italian tax law imposed on truffle hunters earning more than €7,000 a year from truffle-hunting to provide receipts indicating the origin of their truffles upon the initial sale to a middleman.
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