Truffle Market Evolution: An Application of the Delphi Method

Habitat is more important than climate for structuring soil fungal communities associated in truffle sites

The ectomycorrhizal fungi Tuber melanosporum Vittad. and Tuber aestivum Vittad. produce highly valuable truffles, but little is known about the soil fungal communities associated with these truffle species in places where they co-occur. Here, we compared soil fungal communities present in wild and planted truffle sites, in which T. melanosporum and T. aestivum coexist, in Mediterranean and temperate regions over three sampling seasons spanning from 2018 to 2019. We showed that soil fungal community composition and ectomycorrhizal species composition are driven by habitat type rather than climate regions. Also, we observed the influence of soil pH, organic matter content and C:N ratio structuring total and ectomycorrhizal fungal assemblages. Soil fungal communities in wild sites revealed more compositional variability than those of plantations. Greater soil fungal diversity was found in temperate compared to Mediterranean sites when considering all fungal guilds. Ectomycorrhizal diversity was significantly higher in wild sites compared to plantations. Greater mould abundance at wild sites than those on plantation was observed while tree species and seasonal effects were not significant predictors in fungal community structure. Our results suggested a strong influence of both ecosystem age and management on the fungal taxa composition in truffle habitats.

From Nontargeted to Targeted Analysis: Feature Selection in the Differentiation of Truffle Species (Tuber spp.) Using 1H NMR Spectroscopy and Support Vector Machine

The price of different truffle types varies according to their culinary value, sometimes by more than a factor of 10. Nonprofessionals can hardly distinguish visually the species within the white or black truffles, making the possibility of food fraud very easy. Therefore, the identification of different truffle species (Tuber spp.) is an analytical task that could be solved in this study. The polar extract from a total of 80 truffle samples was analyzed by 1H NMR spectroscopy in combination with chemometric methods covering five commercially relevant species. All classification models were validated applying a repeated nested cross-validation. In direct comparison, the two very similar looking and closely related black representatives Tuber melanosporum and Tuber indicum could be classified 100% correctly. The most expensive truffle Tuber magnatum could be distinguished 100% from the other relevant white truffle Tuber borchii. In addition, signals for a potential Tuber borchii and a potential Tuber melanosporum marker for targeted approaches could be detected, and the corresponding molecules were identified as betaine and ribonate. A model covering all five truffle species Tuber aestivum, Tuber borchii, Tuber indicum, Tuber magnatum, and Tuber melanosporum was able to correctly discriminate between each of the species.

Sustainable cultivation of the white truffle (Tuber magnatum) requires ecological understanding

The white truffle (Tuber magnatum Picco.; WT) is the most expensive and arguably also the most delicious species within the genus Tuber. Due to its hidden belowground life cycle, complex host symbiosis, and yet unknown distribution, cultivation of the enigmatic species has only recently been achieved at some plantations in France. A sustainable production of WTs under future climate change, however, requires a better ecological understanding of the species' natural occurrence. Here, we combine information from truffle hunters with a literature review to assess the climatic, edaphic, geographic, and symbiotic characteristics of 231 reported WT sites in southeast Europe. Our meta-study shows that 75% of the WT sites are located outside the species' most famous harvest region, the Piedmont in northern Italy. Spanning a wide geographic range from ~ 37° N in Sicily to ~ 47° N in Hungary, and elevations between sea level in the north and 1000 m asl in the south, all WT sites are characterised by mean winter temperatures > 0.4 °C and summer precipitation totals of ~ 50 mm. Often formed during past flood or landslide events, current soil conditions of the WT sites exhibit pH levels between 6.4 and 8.7, high macroporosity, and a cation exchange capacity of ~ 17 meq/100 g. At least 26 potential host species from 12 genera were reported at the WT sites, with Populus alba and Quercus cerris accounting for 23.5% of all plant species. We expect our findings to contribute to a sustainable WT industry under changing environmental and economic conditions.

Aromatic profile of black truffle grown in Argentina: Characterization of commercial categories and alterations associated to maturation, harvesting date and orchard management practices

Black truffle (Tuber melanosporum) is one of the most appreciated fungi in the world mainly due to its aromatic properties. In the emerging markets such as Argentina, the aroma of locally produced truffles has not been described yet. The volatile organic compounds (VOCs) from 102 black truffles from Argentina were analyzed using solid phase microextraction gas chromatography coupled with mass spectrometer detector (SPME-GC-MS). Several factors such as commercial category, maturity stage, host tree, geographical origin, and aromatic defects detected during classification were also registered and considered. As a result, 79 VOCs were detected, among which 2-methyl-propanal, 2-butanone, 2-methyl-1-propanol, butanal-3-methyl, 3-methyl-1-butanol, 2-methyl-1-butanol were present in high percentage in fresh mature truffles, whereas immature truffles were associated with 3,5-dimethoxytoluene, 2-phenyl-2-butenal, 2,3-dimethoxytoluene. The Argentine black truffles showed significant similarities in their aromatic profile when compared with their Australian and European counterparts, but with some distinctive notes.

Pressurized Liquid (PLE) Truffle Extracts Have Inhibitory Activity on Key Enzymes Related to Type 2 Diabetes (α-Glucosidase and α-Amylase)

An optimized PLE method was applied to several truffle species using three different solvent mixtures to obtain bioactive enriched fractions. The pressurized water extracts contained mainly (1 → 3),(1 → 6)-β-D-glucans, chitins, and heteropolymers with galactose and mannose in their structures. The ethanol extracts included fatty acids and fungal sterols and others such as brassicasterol and stigmasterol, depending on the species. They also showed a different fatty acid lipid profile depending on the solvent utilized and species considered. Ethanol:water extracts showed interesting lipids and many phenolic compounds; however, no synergic extraction of compounds was noticed. Some of the truffle extracts were able to inhibit enzymes related to type 2 diabetes; pressurized water extracts mainly inhibited the α-amylase enzyme, while ethanolic extracts were more able to inhibit α-glucosidase. Tuber brumale var. moschatum and T. aestivum var. uncinatum extracts showed an IC₅₀ of 29.22 mg/mL towards α-amylase and 7.93 mg/mL towards α-glucosidase. Thus, use of the PLE method allows o bioactive enriched fractions to be obtained from truffles with antidiabetic properties.

Aromatic changes in home-made truffle products after heat treatments

Truffles are highly valued by their aromatic properties and can aromatize food products. However, the truffle aroma could be reduced or lost with heat treatments (pasteurization and sterilization) necessary for products security and safety. In this study, sunflower oil and honey were aromatized with black truffle (lyophilized and fresh) using two different concentrations (5 and 10 %) for 24 h and then heat treatments (pasteurization and sterilization) were carried out. Truffle organic volatile compounds from products were investigated by SPME-GC-MS and sensory analysis by trained panel. More than 80 compounds were detected. Some of them were affected differently by heat process depending on the food matrix. Professional tasters scored higher key aromatic attributes such as sulphurous and olive oil in fresh truffle products, regardless the heat treatment applied.

Territorial Marketing Based on Non-Wood Forest Products (NWFPs) to Enhance Sustainable Tourism in Rural Areas: A Literature Review

It is often seen how a distinctive feature of a territory is used as a brand to create an image that attracts tourists to the region. This is so-called “territorial marketing”, and together with this brand, connected products and services, usually related to recreation, gastronomy and well-being, are offered. Non-wood forest products (NWFPs), such as mushrooms, truffles, aromatic and medicinal plants, nuts and berries, are natural products connected to local traditions that contribute to rural economies, culture and society. This becomes particularly prominent when used as elements of identity to brand specific geographical areas such as the “Chestnut Route”, the “Cranberry Valley” or the “Truffle Way”. This review aims to delve into the understanding of this link between NWFPs and sustainable tourism through territorial marketing and to discuss the different perspectives that address this field, including the methodologies used for the studies, as well as to identify the main research topics tackled in the literature, territorial marketing models and the challenges for its development. The results show the multidisciplinary nature of this field of research, addressed primarily by economists through qualitative surveys and case studies. Most authors emphasize the growing interest in territorial marketing in rural areas as well as the importance of involving the local population in the implementation process. Several studies offer a territorial marketing process model, among which stakeholders’ participation, place identity and image, as well as their interaction, are main aspects to be considered when developing this strategy. A new territorial marketing model is proposed. While it is an emergent research field, studies focused on territorial marketing based on NWFPs to attract tourism remain a research niche.

The Market Evolution of Medicinal and Aromatic Plants: A Global Supply Chain Analysis and an Application of the Delphi Method in the Mediterranean Area

There is an increasing evidence for the significant value and potential of Medicinal and Aromatic Plants (MAPs) worldwide. Among other non-wood forest products, MAPs are considered a key element of sustainable forest management and economic development. As part of Mediterranean cultural heritage, these plants are a major driver of rural tourism, in many areas representing an important raw material for various bio-based industrial sectors. Besides their economic value, MAPs enhance social integration and maintain gender balance as harvesting and processing MAPs is clearly a female dominated task. Despite the prominent contribution of MAPs to local development, conservation of biodiversity and the development of the traditional Mediterranean food system, many challenges and knowledge gaps could potentially place the sector’s development at risk. The aim of this work is to examine the present situation of the MAPs sector in the most productive countries around the Mediterranean and to identify future challenges and priority actions to develop the MAPs sector in the region. To do so, a supply chain analysis was performed to identify the main stakeholders involved. Various experts from Croatia, France, Greece, Spain, and Tunisia participated in the SWOT analysis and the Delphi approach employed in this study. The results highlight the main challenges facing the sector in Mediterranean countries. Five groups of challenges are identified, related mainly to certification and labelling, life quality and wellbeing, market development, research development, and transforming and processing. To overcome these challenges, a set of actions is validated by the interviewed experts with the aim of improving marketing strategies and including various innovations related to political, legal, organisational, and institutional frameworks.

Fungal and Bacterial Communities in Tuber melanosporum Plantations from Northern Spain

Tuber melanosporum (Ascomycota, Pezizales) is an ectomycorrhizal fungus that produces highly appreciated hypogeous fruiting bodies called black truffles. The aim of this paper was to research the composition of ectomycorrhiza-associated fungal and bacterial communities in T. melanosporum oak plantations. Results of this paper showed the competitive effect of T. melanosporum on other fungal species, especially other mycorrhizal and pathogenic species. T. melanosporum was shown to be associated mainly with bacteria, some of them important for their properties as mycorrhizal helper bacteria. A dendrogram analysis of co-occurrence showed that T. melanosporum tended to co-occur with the following bacteria species: Singulisphaera limicola, Nannocistis excedens and Sporosarcina globispora. In addition, it was linked to fungal species such as Mortierella elongata, M. minutissima, Cryptococcus uzbekistanensis, C. chernovii and C. aerius. This study provides an exhaustive analysis of the diversity, structure and composition of fungal and bacterial communities associated with T. melanosporum to enhance understanding of the biology, composition and role of these communities in truffle plantations.

Methods used for extraction of plant volatiles have potential to preserve truffle aroma: A review

Truffles are considered one of the world's most highly prized foods mainly due to their desirable organoleptic properties and rarity. However, truffles are seasonal (harvested mostly in winter from June to August in the Southern Hemisphere and from December to February in the Northern Hemisphere) and extremely perishable. Truffles deteriorate rapidly showing undesirable changes within 10 days from harvest in aroma and visual appearance after harvest. The very short postharvest shelf life (about 7-10 days) limits the potential for export and domestic consumption all year round. Several preservation methods have been studied to prolong their shelf life without the loss of aroma. However, all traditional preservation techniques have their own shortcomings and remain challenging. The extraction of natural truffle aroma volatiles for food applications could be a potential alternative to replace the existing synthetic flavoring used for processed truffle products. Four commonly used extraction methods for recovering volatile compounds from plants, namely, supercritical carbon dioxide extraction, Soxhlet extraction, distillation, and cold pressing, are critically analyzed. Up to date, existing research about the extraction of aroma volatiles from truffles is limited in the literature but based on the volatility of the key truffle volatile compounds, supercritical carbon dioxide extraction may offer the best possibility so that a natural truffle-based product that can be used in food applications throughout the year can be made available.

Indigenous Forestry Tourism Dimensions: A Systematic Review

Tourism activities developed in forested areas are a non-wood forest exploitation method that contributes to sustainability objectives, even more so when they consider the participation of the community and the government in favor of its conservation. Under this context, this article will review the different investigations that relate to indigenous tourism, the conservation of the ecosystem and what attributes are important when measuring them. To do this, a scientometric meta-analysis was carried out, which extracts a set of articles that strictly refer to the themes of indigenous tourism in forests, considering two databases integrated into the Core Collection Web of Science, the selection process of which is aligned with the guidelines of the PRISMA methodology, establishing, with the PICOS tool, the eligibility criteria of the articles, which were applied to a qualitative systematic review. Finally, a model for measuring attributes in levels on indigenous tourism stands out, which incorporates the limit between the number of visitors to the tourist destination; the incorporation of tourists guides the identification of the necessary infrastructure facilities for an adequate experience and environmental conservation.