A blog devoted to exploring wines made from unusual grape varieties and/or grown in unfamiliar regions all over the world. All wines are purchased by me from shops in the Boston metro area or directly from wineries that I have visited. If a reviewed bottle is a free sample, that fact is acknowledged prior to the bottle's review. I do not receive any compensation from any of the wineries, wine shops or companies that I mention on the blog.
Monday, June 4, 2012
Tintilla de Rota - Jerez, Spain
As in many other posts (see Turbiana and Hondarrabi Zuri, among others), my journey began with with The Oxford Companion to Wine, whose online version automatically redirects you to the entry on Graciano when you try to search for Tintilla de Rota. Within the entry for Graciano the writers state "it has also been certified through DNA profiling that the Tintilla de Rota grape of Jerez and Bovale Sardo on Sardegna are both Graciano." Since I've found mistakes in the Oxford Companion in the past regarding these kinds of issues, I set about trying to find the articles that would corroborate their account. The first article that I found was about the Tintilia grape from the Molise region of Italy (citation 1 below). In this article, the researchers analyzed several different examples of the Tintilia grape to see if it had any relationship to Tintilla de Rota (which they equate with Graciano with no discussion), Aglianico, a grape called Tintilia from Sardinia, several different grapes called Bovale Sardo or Bovale Grande and Monastrell, among others. This team found no relationship between any of the grapes listed above and were able to establish that each was a separate cultivar. In 2007, another Italian team (citation 2 below) analyzed the Bovale family of grapes on Sardinia and their research found that Bovale Sardo was identical to Graciano and another grape called Cagnulari. Who do we believe? The first study above was published in a peer reviewed journal, while the second was presented at a conference and published in the proceedings, so I'd be inclined to lean towards the former, but the OCW seems to lean more towards the latter.
Whatever the relationship is between Graciano and Bovale Sardo, what I was really interested in was the relationship between Graciano and Tintilla de Rota. Searching for that link, I came across this site (in Spanish) which seems to refer to a study that linked not only Graciano and Tintilla de Rota, but also a grape called Parraleta from the Somontano region of Spain. When I tried to track this article down, I came across another article (citation 3 below) from a Spanish research group (one of whom was supposedly in the research group in the study that I was actually trying to find) whose final sentence reads: "Results of this work confirm the trueness-to-type of 'Parraleta' accessions studied and also that this variety is not a synonymy of 'Graciano' cultivar."
None of this was really getting me that much closer to answer the question that I started with, but it was starting to make me wonder. I understand that scientific discovery is a process, but it's really difficult to get a feel for what's going on just by following the literature. For one thing, the literature is really spread out. I've had to look in about a dozen different journals to find some of these articles and have had to consult a few different academic search engines. For another thing, much of the literature is contradictory and there's rarely a third article published that definitively settles the score between two previously published papers that are at odds with one another. Since most of these grapes are pretty obscure there isn't exactly a continuing dialogue about them, and once a team has published their results, they seem to move on to the next project and not really engage with any contradictory studies.
By far the biggest problem, and the one that I think poses a serious danger to the credibility of the whole enterprise, is the way in which the researchers gather samples. I mention in my post on Hondarrabi Zuri that the root of that confusion was a mislabeled plant in a university collection. This problem is apparently somewhat widespread, as it shows up in the papers above more often that I feel comfortable with. In one of the studies (citation 1), the research team took several samples of each plant to verify that each was identical and that their test was working correctly. They took two samples of Bovale Sardo and two of Bovale Grande, but each of these samples came back with different DNA profiles, indicating that they were actually different plants (the methodology wasn't flawed as they took 21 different samples of Tinitilia from Molise and all 21 came back the same). Another study (citation 4 below), which was an update to citation 2, indicates that one of the samples they tested that was labeled Graciano actually turned out to be Trepat, while one of the samples labeled Parraleta turned out to be Mandón.
The problem here forms a kind of a circle. The samples that the scientists use are held and labeled in a university collection. Those samples were obtained from the field at some point where they were identified either ampelographically or by the farmer to the person collecting the sample. The problem is that there isn't any good way to verify whether the identification is correct at this point. You can't run DNA testing on a plant that you don't have a DNA baseline for. When you go to run DNA analysis for the first time on something you're calling Graciano, you're calling it that based on a visual inspection of the grape or by someone else's testimony to that effect, and the DNA that you get as a result ends up defining Graciano whether it's actually Graciano or not. The exact problem that DNA analysis is trying to solve is ultimately rooted in the same methods of identification that caused the problem in the first place, namely visual inspection and morphological classification (ampelography, in short). If you're running a DNA analysis on a grape that was misidentified in the field (or in the lab due to bad labeling), then the analysis is based on a faulty premise and the information is no good. In the case of Hondarrabi Zuri that I wrote about previously, the error was fairly easy to spot, but what about in subtler cases? If two institutions have a vine called Graciano and analysis on each institution's sample shows that they're two different vines, how do you decide which is the real Graciano? What if 10 institutions have a sample called Graciano and four different DNA patterns are found between them? The situation isn't quite that dire, but it is troubling
In case you've forgotten during that extended digression, the question that I was ultimately trying to answer was whether Graciano and Tintilla de Rota were the same grape. After a great deal of searching, I believe I finally found the paper that everyone is referencing (citation 5 below). This study was done by a Spanish team on a wide variety of Spanish grapes, and their paper reads "microsatellite analysis alone established 'Graciano' (D.O.Ca. Rioja), 'Parraleta' (D.O. Somontano) and 'Tintilla de Rota' (variety traditionally cultivated in Jerez) as the same genotype." That's the only reference I've been able to find in the literature and I've found nothing anywhere else to contradict it, other than the fact that Parraleta and Graciano may actually not be identical after all. Nearly every secondary source is unanimous in their agreement that Graciano is Tintilla de Rota, and without any evidence to the contrary, it looks like we have to agree.
Tintilla de Rota is used in both table wine and fortified wine production around the Sherry region of Spain. Rota is the name of a town in the Sherry region whose sandy soils are particularly well suited to the cultivation of the Tintilla grape. It has been known in this region since the 1500's, but was pushed to the brink of extinction in the 1950's as an American military base was constructed where many Tintilla vines were once planted. The wine that I was able to find was the fortified version from Emilio Lustau, which I picked up my friends at the Spirited Gourmet for about $45 (I believe Curtis Liquors carries this as well). To make this wine, the grapes are picked and then left out in the sun for two or three weeks to dry out. They are then placed in tubs and covered with mats to minimize the amount of air contact. They're left in the tubs for about a month and periodically stirred before being pressed. The wine is fortified to about 17% (mine was 17.5%) and then aged for awhile in casks before being bottled.
Pedro Ximenez Sherry. It's comparable to other fortified wines in terms of price and is interesting enough (and definitely tasty enough) to carry that kind of price tag. Whether it's the same as Graciano or not, this is definitely unlike any Graciano-based wine you may have had before and is definitely worth a try if you run across it on the shelves of your local wine shop.
1) Reale, S., Pilla, F., & Angiolillo, A. (2006). Genetic analysis of the Italian Vitis vinifera cultivar 'Tintilia' and related cultivars using SSR markers. Journal of Horticultural Science & Biotechnology, 81 (6), 989-994.
2) Nieddu, G., Nieddu, M., Cocco, G.F., Erre, P., & Chessa, I. (2007). Morphological and genetic characterization of the Sardinian 'Bovale' cultivars. Acta Horticulturae, 754, 49-54.
3) Montaner, C., Martin, J.P., Casanova, J., Marti, C., Badia, D., Cabello, F., & Ortiz, J.M. (2004). Application of microsatellite markers for the characterization of 'Parraleta': an autochthonous Spanish grapevine cultivar. Scientia Horticulturae, 101, 343-347.
4) Buhner-Zaharieva, T., Moussaoui, S., Lorente, M., Andreu, J., Nunez, R., Ortiz, J.M., & Gogorcena, Y. (2010). Preservation and molecular characterization of ancient varieties in Spanish grapevine germplasm collections. American Journal of Enology and Viticulture, 61 (4), 557-562.
5) Borrego, J., Rodriguez, I., de Andres, M.T., Martin, J., Chavez, J., Cabello, F., & Ibanez, J. (2001). Characterisation of the most important Spanish grape varieties through isoenzyme and microsatellite analysis. Acta Horticulturae, 546, 371-375.