Is Trebbiano di Lugana (Turbiana) the same grape as Verdicchio? Or is it a distinct biotype?

Above: Turbiana vines on the Sansonina estate in Lugana (Peschiera).

In recent years, many wine writers and bloggers have written about the genetic kinship between Verdicchio and Trebbiano di Lugana (also known as Turbiana, the grape used to make Lugana).

Although some claim the show-stopping discovery to be news, in fact the genetic link, not to Turbiana but rather Trebbiano from Italy’s Veneto region (where Lugana is made), was revealed nearly 30 years ago.

As leading Italian ampelographer Ian D’Agata writes in his excellent survey of Italian grape varieties (Native Wine Grapes of Italy, UC Press, 2014), Italian ampelographers first identified the genetic connection between Verdicchio and Trebbiano di Soave (Trebbiano di Lugana’s sibling) in 1991.

“In 1991, on the basis of ampelographic descriptions and enzyme analysis, [leading Italian ampelographers] demonstrated that Trebbiano di Soave is identical to Verdicchio…”

But when it came to Trebbiano di Lugana (Turbiana), the kinship question became a little more complicated.

“Subsequently, [another group of scholars] performed DNA profiling not just on Verdicchio and Trebbiano di Soave but also on Trebbiano di Lugana” also known locally as Turbiana di Lugana.

“The varieties have identical alleles at all ten loci; the likelihood of that happening and the two varieties not being the same is one in eight billion.”

(The “loci” he refers to are “microsatellite loci” [sing. locus], “a tract of repetitive DNA in which certain DNA motifs… are repeated”; an “allele” is “a variant form of a given gene.”)

“But,” D’Agata continues, “the researchers also found an abnormal allele of five hundred nucleotide bases in the VVMD36 locus that allows genetic differentiation between Trebbiano di Soave and Trebbiano di Lugana, which on the basis of these results are probably more correctly viewed as biotypes.” (italics mine)

(“VVMD” is shorthand for a class of vitis vinifera microsatellites.)

Noting that question of the direct link between Turbiana and Verdicchio has not been definitely established, D’Agata writes that “clearly, further studies are needed.”

So it turns out that Turbiana and Verdicchio are related but not identical, at least according to D’Agata, the leading scholar in the field.

For the record, the authors of the landmark Wine Grapes (HarperCollins 2012) write that “Trebbiano di Soave, Trebbiano Valtenesi and Trebbiano di Lugana are all identical to VERDICCHIO BIANCO.”

It would seem that D’Agata has had the last word (even though the word is still out, as he notes).

Lugana: Origin of the place name

Philology — the study of words and their origins — is an inexact science. And the origin of the place name Lugana is a classic example of toponymic (place name) philology where we will never have a precise answer to the question where did the name Lugana come from?

Most scholars of Veneto toponomastics (the study of place names) believe that the name Lugana comes from the Latin lucus meaning a wood, grove, or thicket of trees sacred to a deity.

The name of Lugo, a hamlet (frazione) in Grezzana township (Verona province) lies not far from Lugana and is also believed to come from lucus.

There are also ancient references to Lugana as Lugana silva, in other words, Lugana wood (in the sense of woods). This is another indication that lucus is the probable origin of the current-day name.

Neighboring Valpolicella (where Lugo is found) was already a famous area for fine wine production in Roman times and it’s not unlikely that the Romans considered Valpolicella and Lugana, the area lying to the southern coast of Lake Garda, to be sacred spots — because of the excellent wine and olive oil produced there.

Lugana is also a immensely beautiful place with mild weather thanks to the maritime influence of the lake — another reason the Romans may have considered it a special place or lucus.

What is “spontaneous fermentation”?

The Lugana that’s produced from grapes on the Sansonina estate is labeled fermentazione spontanea or spontaneous fermentation in English.

That means that the wine has not been “inoculated” with “cultured yeast” or “select yeast” as it is sometimes called.

Fermentation is the process by which sugar is converted to alcohol by yeast. The microorganisms consume the sugar and one of the byproducts of their feast is alcohol.

Across the world today, the overwhelming majority of the wines produced are made by adding a cultured or lab-grown yeast to the grape must to provoke fermentation. (Cultured yeast can also be called “inoculated yeast.”)

That’s not a bad thing. By no means.

Inoculation allows the winemaker to control the fermentation with precision.

Some winemakers use specific cultured yeast to give their wines particular flavors.

But most producers prefer neutral yeasts that don’t shape the aroma or flavor profile of the wine. A neutral yeast allows the naturally occurring yeast to do its job without the risk of unwanted yeast or or bacteria that could affect the resulting wine.

Spontaneous fermentation, also called “wild ferment” in certain circles, relies solely on the naturally occurring yeast — sometimes also called “ambient yeast” or “native yeast.”

When the Zenato family decided to make a spontaneously fermented Lugana from grapes grown on the 13 hectares of the Sansonina estate, they did so because they wanted the wine to be the purest expression of the place itself.

It’s tricky business to wild ferment your wines. But the results in this case have been spectacular.

To learn more about inoculation and yeast, see the Oxford Companion to Wine entry for “yeast” (subscribers only).