Truffles – mysterious underground mushrooms that grow spontaneously – are one of the delicacies that characterize agri-food production in Italy and France, as well as in other countries. The ABC's to follow.
Premise. Forest and desert truffles
Most of the truffles renowned for use in the kitchen comes from the northern temperate woodlands and forests in Europe, Australia, New Zealand, Asia and North America belong to the genus Tuber.
This analysis dwells on Tuber magnatum Peak (precious white truffle), tuber melanosporum (precious black truffle), Tuber borchii Vittad (bianchetto truffle) e Summer tuber (summer truffle).
Other underground mushrooms, desert truffles, grow in arid and semi-arid areas (e.g. Syria, Iraq, Kuwait, Saudi Arabia, Morocco, Egypt, Tunisia, South Africa) and belong to the genera Terphezia e tyrmania.
From Babylon and ancient Rome to the present day
The appearance of truffles on Earth is attributed to over 100 million years ago, their earliest inscriptions on Babylonian clay tablets date back to 3700 BC. (1)
Ancient Rome he celebrated these precious underground mushrooms in sumptuous banquets, as a sign of the ostentatious wealth and opulence of patrician families.
Over the centuries the growing demand for truffles has stimulated the development of domestication practices and scientific research, to increase their availability.
Botanica
The forest truffle it is the fruiting body of symbiotic edible mushrooms of the genus Tuber, class of the Ascomycetes. Truffles – underground mushrooms, as they complete their entire life cycle underground – are made up of:
- a fertile part (hymenophore), immersed in
- a more or less compact structure (glebe), in turn enclosed by
- a membranous outer layer, protective and sterile (peridium). (2)
The various species of truffles are distinguished by a series of morphological characters such as the shape, the dimensions, the color of the peridium, the appearance and color of the gleba, the perfume.
Il "terroir" – type and quality (pH, humidity and nutrients) of the soil – has an essential role in determining the development of truffles, their size and composition. (3)
Mutual symbiosis
The life cycle and fruiting of truffles, therefore classified as obligate ectomycorrhizal fungi, depend on mutualistic symbiosis with the roots of a host plant. Which ones are they Quercus pubescens Willd., Quercus ilex L., Quercus cerris L., Quercus robur L., Corylus avellanaL., Tilia cordata Mill., Ostrya carpinifolia Scop., Carpinus betulus L., Pinus pinea L., Pinus halepensis L., Pinus nigra L..
The symbiotic bond with these plants it offers organic substance necessary for the development of truffles. Which at the same time, thanks to their high capacity to extract nutrients from the soil, increase their accessibility also by the plant which thus improves growth and PERFORMANCE productive. (4)
Nutritional properties
The nutritional properties of truffles are appreciated for their richness in fiber, protein and amino acids, mineral salts (potassium, magnesium, calcium and phosphorus), vitamin C. (5)
Various species - as T.eastivum, T.borchii, T.melanosporum e T. magnatum – they are also characterized by the presence of unsaturated fatty acids such as oleic acid and linoleic acid.
The contribution of oleic acid has been associated with the reduction of blood cholesterol levels, cardiovascular prevention and inhibition of cancer progression. (5)
Potential health benefits
The potential benefits of health truffles have been explored in a recent scientific review (Read et al., 2020) which highlighted its anticancer, antioxidant, antibacterial, anti-inflammatory and hepatoprotective capacities. (6)
The bioactive compounds (terpenoids, phenols) contained in them, together with polysaccharides and fatty acids, have also shown the potential efficacy of truffles in enhancing the effects of various drugs such as antidepressants, immunostimulants and cholesterol reducers.
Some excerpts of methanol from T.aestivum e T. magnatum then revealed significant cytotoxic effects, in two in vitro experimental studies, against different tumor cell lines. (6)
Organoleptic properties
The aromas unmistakable characteristics of the truffle are linked to volatile organic compounds (volatile organic compounds, VOCs), which play an active role in regulating symbiosis and interactions with other organisms and are released during the entire life cycle:
- only two VOCs (2-methylbutanal, 3-methylbutanal) are present in all truffle species,
- over 200 others (e.g. alcohols, aldehydes, ketones, organic acids and sulfur compounds) are species-specific,
- the chemical synthesis of natural-identical aromas is the basis of food fraud on truffles. (7)
Perfumes and aromas
The Parfums are influenced by the ripening stage of the fruiting body, i "terroir", the microbial flora inhabiting the tissues of the ascocarp, the intraspecific genetic variability:
- the summer truffle (T. aestivum Vittad.) presents notes of sulphur, leather, metal, cooked potato,
- T. magnatum Peak – the white truffle, the rarest and most expensive species, much appreciated in Italian and French cuisine – also recalls the hints of garlic and cheese,
- il T. melanosporum Vittad., black truffle, has a scent similar to that of a humid forest with hints of radish, hazelnut and chicory,
- T. brumale Vittad instead it has a characteristic musky smell, accompanied by earthy notes.
Food container
on the most suitable conservation methods to preserve the organoleptic properties of truffles, he considered the merits and defects of freezing, refrigeration, drying with hot air, modified atmosphere, freeze-drying, irradiation.
The freeze-drying – although decidedly more expensive – it was more effective than other techniques in preserving many VOCs. Freezing alone, like pasteurization and other forms of heating, on the other hand, drastically alter the organoleptic properties of truffles.
Market
Italy and France they are the first countries in the production, processing and marketing of truffles, while Europe is still the first market globally. (8)
The market it is characterized by a relatively stable demand, typical of luxury goods, and conversely volatile prices. With significant peaks, for the most valuable species, in years of low production. (9)
In Italy coexist a local market, linked to the food and wine traditions of the territories of origin, and an international market focused on export. The largest quantities of truffles in Italy are harvested in Umbria, followed by Abruzzo and Marche. (10)
Irene Giunta and Dario Dongo
Cover image from scientific study cited in footnote 6 (Lee et al., 2020). Fig. 2 – Symbiotic life cycle of truffles
Footnotes
(1) National Center for Truffle Studies (2002). The main species of Tuber. tuber.it
(2) Signorini D., Valli O. The truffle, habitat, research and cultivation techniques of black and white. Giunti Demetra, Milan, 1990. ISBN: 8871221400
(3) Streiblová E., Gryndlerová H., Gryndler M. (2011). Truffle brûlé: an efficient fungal life strategy. FEMS Microbiology Ecology. Volume 80, pp 1-8. doi: 10.1111/j.1574-6941.2011.01283.x
(4) Alessandro Deanesi. Truffle, biology and characteristics. https://www.biopills.net/tartufo/ Biopills. 25.3.20
(5) Nina Šiškovič, Lidija Strojnik, Tine Grebenc, Rajko Vidrih, Nives Ogrinc (2021). Differentiation between species and regional origin of fresh and freeze-dried truffles according to their volatile profiles. Food Control, volume 123 https://doi.org/10.1016/j.foodcont.2020.107698
(6) Heayyean Lee, Kyungmin Nam, Zahra Zahra, Muhammad Qudrat Ullah Farooqi (2020). Potentials of truffles in nutritional and medicinal applications: a review. Fungal Biol Biotechnol 7, 9 https://doi.org/10.1186/s40694-020-00097-x
(7) Dario Dongo. Aroma with truffles and Asian 'truffles', watch out for the bin. GIFT (Great Italian Food Trade). 27.11.21
(8) Laureti M. The black truffle and its juridical relationships in Spoleto and Nursino. Proceedings of the first international congress on truffles in Spoleto, 24-25.5.68 (Tipografia Amoretti, Parma, 1968)
(9) Urbani G. (1995). Rational truffle cultivation: analysis of an investment. The Agricultural Informant. Volume 31, pp. 29-32
(10) Boutahir S. (2013). New biotechnologies for the production of mycorrhizal plants with truffles. PhD thesis at the University of Bologna
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
Irene Giunta
Graduated in environmental and forestry sciences in Palermo, specialized in sustainable rural development at the Faculty of Agriculture of Perugia. She is a mycologist, she boasts numerous experiences in truffle cultivation
