Sopra recent years it has become increasingly common to across Italian white wines characterized by evident hints of hydrocarbon, petroleum, kerosene naphtha. At one time these quaderno were considered almost exclusively the heritage of some mature Rieslings coming from the most suitable regions of Germany and Alsace. Today, however, they are found with increasing frequency durante Verdicchio, Vermentino, Timorasso, Fiano, Garganega, Trebbiano, Carricante, Nascetta, Pecorino and even durante varieties aromatically very distant from Riesling.
The question is inevitable: are we really faced with a new expression of Italian territories and varieties are we witnessing the spread (and, at times, exaltation) of a phenomenon linked mainly to agronomic, climatic and oenological critical issues which risks standardizing some of our country’s white wines?
What is TDN
The compound responsible for the petroleum and kerosene quaderno is TDN (1,1,6-trimethyl-1,2-dihydronaphthalene), a norisoprenoid resulting from the degradation of carotenoids present durante grape skins. Its precursors accumulate during maturation and are subsequently transformed over time, especially during bottle refinement.
At low concentrations TDN can contribute to the aromatic complexity of some wines, durante particular Riesling, where it represents a historically recognized component of the evolutionary bouquet. However, when the concentration increases, the petrolatum character becomes dominant and can transform into a real sensorial defect (even durante Rieslings).
Scientific research has also shown that the perceptual threshold of TDN is much lower than previously thought: already at around 2 µg/L the compound can be perceived by many tasters.
Climate change as an accelerator
The international scientific community agrees acceso one point: the increase durante temperatures and solar radiation favor the formation of TDN precursors. The direct exposure of the bunches to UV rays and temperatures above 30°C determine a greater accumulation and more rapid degradation of carotenoids, increasing the risk of developing petrolatum hints durante the wines.
It is coincidence that the studies conducted by the Neustadt and Braunschweig institutes have identified global warming as one of the main factors responsible for the increase durante TDN concentrations durante contemporary Rieslings.
What is avvenimento today durante German vineyards also concerns Italy more and more closely, where many vineyard areas experience longer summers, higher temperatures and a greater frequency of heat waves.
Excessive defoliation and bunches too exposed
Over the last twenty years, modern viticulture has often favored greater exposure of the bunches to improve health, phenolic maturation and aromatic concentration, even if many winemakers sensitive to the critical issues linked to climate change are adopting practices more oriented towards shading.
However, research has highlighted how excessive defoliation represents one of the main factors increasing TDN. Sopra fact, direct light accelerates the degradation of carotenoids and increases the formation of the precursors responsible for the hydrocarbon quaderno.
Sopra many Italian areas, bunches completely exposed during the hottest hours of the day are still observed today. A practice that can be partially effective for some red varieties but which durante whites risks compromising the aromatic finesse and favoring the appearance of petrolatum characters, if not “cooked” hints.
The role of the closure: technical caps and screws
Another aspect rarely addressed concerns the role of closures.
TDN increases during bottle storage and the rate of formation can be influenced by the type of cork used. Specific studies indicate that storage conditions, the type of closure and the limited oxidative exchange can affect its evolution.
The increasingly widespread adoption of high-tight technical caps screw caps has certainly reduced the variability between individual bottles of the same bottling batch but has also favored highly reductive environments that can accelerate the emergence of some odorous molecules that are not always desirable during refinement, such as TDN. (It should be noted that durante wines that use technical corks screw caps we find it more difficult to find defects even when we are faced with “d’avanguardia/flavours” linked to excess reduction, aromatic scalping and the transfer of exogenous aromas, such as hints of vinyl for example. This opens up an interesting reflection acceso how much the producer today is willing to sacrifice the maximum expressiveness of his wine durante favor of greater homogeneity, even where wines with cork stoppers show defects are durante most cases changed, ergo not worn, while those with technical caps screws are usually not replaced despite any obvious defects. I will have the opportunity to delve deeper into this topic durante the coming months).
It’s not about demonizing modern closures, but about understanding how every technological choice has sensorial consequences that must be evaluated acceso a case-by-case basis.
Transport, storage and thermal shock
A further element that is often underestimated is the management of logistics and conservation.
TDN precursors continue to transform into bottled wine and high temperatures during transportation and storage can significantly accelerate the phenomenon.
Containers crossing oceans, non-air-conditioned warehouses, prolonged stops under the sun significant temperature variations can anticipate the emergence of petrolatum quaderno which, durante optimal conditions, would have manifested themselves many years later perhaps would never have emerged with such intensity.
This is a particularly relevant aspect for wines intended for , where the cold chain is rarely maintained continuously.
When hydrocarbon stops being identity
Here the real cultural crux of the issue emerges.
Sopra recent years, some wine criticism and communication have contributed to transforming the hint of hydrocarbon into a sort of quality mark. Petrol quaderno are increasingly celebrated as an indicator of the complexity, longevity and nobility of the wine.
But this reading risks being profoundly misleading.
Sopra Riesling, TDN represents a historically recognized component of some territorial expressions and some evolutionary paths. Sopra many other vines, however, there is documented link between varietal identity and the presence of petrolatum hints.
When a Verdicchio, a Vermentino, a Fiano a Carricante are described positively especially for their hydrocarbon quaderno, there is the risk of attributing value to a phenomenon that could simply derive from thermal tensione, excessive exposure of the bunches, questionable agronomic management less than optimal conservation.
Sopra other words, there is a risk of confusing a consequence with a quality.
The danger of sensorial homologation
The most serious consequence is homologation.
If producers, critics and consumers begin to consider any hint of oil durante white wines desirable, the system will unconsciously tend to favor practices that increase TDN.
The result will be a progressive flattening of territorial differences.
The broom quaderno of a Mediterranean Vermentino, the citrus fruits of an Etna Carricante, the anise of Verdicchio, the medicinal herbs of Fiano, the almond of the Garganega the flint of some volcanic terroirs risk being progressively covered by a common aromatic character, transversal and substantially disconnected from the varietal identity.
It is the paradox of contemporary oenology: celebrating as an expression of terroir what is often the result of a global climatic and technological phenomenon.
Conclusions
The TDN is not the enemy. Like all aromatic molecules durante wine, it can contribute to complexity when present durante the right proportions and durante the right varietal context.
The problem arises when its presence is automatically interpreted as synonymous with quality.
Hydrocarbon is not a territorial flavor. It is not a reliable indicator of greatness. It is not necessarily proof of longevity.
Very often it is simply the sign of greater sun exposure, an anomalous accumulation of carotenoids, extreme climatic conditions, accelerated evolution durante the bottle less than ideal storage.
Sopra an periodo durante which climate change is already redesigning the sensorial profile of the world’s wines, the real challenge is not to chase TDN wherever it is found, but to preserve the aromatic diversity that makes each grape variety and each territory unrepeatable. My fear is that the strong recognizability of this scent is causing a sort of “habituation” acceso the part of producers and tasters, who are increasingly inclined to willingly accept and, durante some cases, to see what is, to all intents and purposes, olfactory homologation as an aromatic target to be achieved. So much so that, more and more often, we hear “local” varieties being compared to Riesling durante a qualifying way, when the need to resemble something else, often very different from what our varieties are and can be, should be considered a sort of defeat for those who operate durante compliance with their own territorial and varietal identity.
It goes without saying that, as mentioned at the beginning of this article, when TDN is well integrated and represents one of the nuances of the aromatic spectrum of a wine, it can confer complexity of great pleasure and consistent with an identity which is influenced by the vintage, exposure and choices of the producer (all components that we cannot avoid considering part of a broad concept of Terroir).
Francesco Saverio Russo
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