Anthony Road Rules

Anthony Road Semi-Dry Riesling 2007
Appelation: Finger Lakes
Varietal: Riesling
ABV: 12.3%
RS: 1.9%
Price Point $16
Notes:
Nose: lime and pineapple on the nose, but the first thing I notice is our old friend petrol*, which in this case adds some nice complexity to an otherwise crisp and fruity nose.
Palate: rich {mouthfeel} with refreshing acidity. Very nice on the palate. The sweetness and overall body give a lemon chiffon feel. Really enjoyable.

Rating:

I have not yet been to Anthony Road, but I have heard winemaker Johannes Reinhardt described as “dreamy”. So, that’s good for the ladies. If his other wines are just as dreamy, then they are doing a fine job out there. Riesling month is off to a delicious start!

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1,1,6-trimethyl-1,2-dihydronaphthalene, or TDN to the syllabically challenged.

*Science!
The petrol component, as we discussed in the riesling ice wine bonanza, usually shows up in riesling wines after a bit of aging. But this wine is a 2007? What’s going on? Let’s look into the origins of the aroma compound.

The molecule in question is 1,1,6-trimethyl-1,2-dihydronaphthalene, which is thankfully abbreviated to TDN. TDN’s aromas can be described as kerosene, burned rubber, or the much nicer French term goût petrol. Nothing with a circumflex (château, l’Hôpital’s rule, etc.) can be that bad, right? While it tends to add a bit of complexity to a fruity bouquet increasing amounts of this compound can make it an off-aroma.

It’s thought that TDN arises from the breakdown of carotenoids in wine. What are carotenoids? Carotenoids are color compounds. In the fall, when chlorophyll in trees breaks down, what’s left are the carotenoids, yellow, orange, red, etc. They mostly serve to protect chlorophyll by absorbing damaging wavelengths of sunlight. As such, carotenoids are usually higher in grapes grown in hot regions with lots of sun. Carotenoid concentration can affect the emergence of TDN as wine ages. Also, carotenoids are produced until veraison (i.e. the beginning of ripening), then degraded during maturation. So (1) the more concentrated your carotenoids (e.g., hot, dry year), and (2) the longer your maturation time, the more carotenoid breakdown products you’ll end up with in your wine.

2007 was a hot, dry year in the Finger Lakes. As such, many producers produced very ripe grapes, and let them hang for quite a while for maximum ripeness. In riesling terms, this could be a recipe for TDN, if not now then in a few years. On a side note, not all carotenoid breakdown products are bad. β-damascenone (canned apple), β-ionone, and the aptly named Riesling acetal all are the result of carotenoid breakdown. I’ll be tasting quite a few 2007s during “May is riesling month”, so stay tuned!

If you want some real science, check out this quote from an excellent and very detailed review of the subject of carotenoid breakdown by Maria Manuela Mendes-Pinto in Archives of Biochemistry and Biophysics (2009) which was the source for much of the above information. This is the kind of stuff I love.

It is important to take into consideration that the model systems studied for thermal degradation of β-carotene require extreme temperature over a long period of time, sometimes in the presence of organic solvents such as ethanol and benzene and . Although these conditions are not representative of the natural conditions that can contribute to the degradation of carotenoids and norisoprenoids formation, they are valid studies because they can be indicators of the naturally occurring reactions. The formation of TDN and Riesling acetal by acid hydrolysis of megastigmane structures as intermediates has been proposed by Winterhalter in 1991. The existence of multiple possible precursors for TDN, vitispirane and also of β-damascenone, was observed in heated juice of Riesling grapes; the glycosylated forms were hydrolysed to release the corresponding aroma norisoprenoids. In Riesling wines, TDN, vitispirane and Riesling acetal were formed in high concentrations by acid hydrolysis of the glycosylated precursors. While the precursor of β-damasenone has already been suggested (megastigma-6,7-dien-3,5,9-triol) the precursors of TDN and Riesling acetal were proposed later; the glycosylated form of 2,6,10,10-tetramethyl-1-oxaspiro[4.5]dec-6-ene-2,8-diol identified in wines was considered as a natural precursor of TDN after acid hydrolysis, while 1,4-dihydroxy-7,8-dihydro-β-ionone was considered as the precursor of Riesling acetal. This work also provided evidence of multiple precursors of TDN as previously suggested in related work with the same Riesling wine (P. Winterhalter, M.A. Sefton and P.J. Williams, Am. J. Enol. Vitic. 41 (1990), pp. 277–283).[74].

I guess it makes more sense with the figures.

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