Editing Riesling (section)

==Longevity==
{{See also|Aging of wine}}
[[File:Riesling Kabinett 1975 in glass.jpg|thumb|200px|A German Riesling from the 1975 vintage, an Erbacher Siegelsberg Kabinett from Schloss Reinhartshausen in Rheingau, uncorked at 32 years of age in 2007. It shows the typical golden to amber colour of aged Riesling, which is shared by many other aged white wines.]]

Riesling wines are often consumed when young, when they make a fruity and aromatic wine that may have aromas of green or other apples, grapefruit, peach, gooseberry, honey, rose blossom or cut green grass, and usually a crisp taste due to the high acidity.<ref>Owen Bird, ''Rheingold - The German Wine Renaissance'', Arima Publishing 2005, p. 91 {{ISBN|978-1-84549-079-9}}</ref> However, Riesling's naturally high acidity and range of flavours make it suitable for extended aging. International wine expert [[Michael Broadbent]] rates aged German Rieslings, some hundreds of years old, highly.<ref>Michael Broadbent, ''Vintage Wines'' Little, Brown 2002 pg 343 {{ISBN|0-15-100704-7}}</ref> Sweet Riesling wines, such as German [[Trockenbeerenauslese]], are especially suited for cellaring since the high sugar content provides for additional preservation. However, high-quality dry or off-dry Riesling wine is also known not just to have survived but also to have been enjoyable at an age exceeding 100 years.<ref>[http://www.jancisrobinson.com/articles/winenews060429] {{Webarchive|url=https://web.archive.org/web/20130618061209/http://www.jancisrobinson.com/articles/winenews060429|date=2013-06-18}}[[Jancis Robinson]].com: Exploding myths about German wine.</ref>

The [[Bremen Ratskeller|Ratskeller]] (council wine cellar) of the townhall of [[Bremen (city)|Bremen]], Germany, stores 650+ German wines, including Riesling-based wines, often in barrel and back to the 1653 vintage.<ref>[[Michael Broadbent]], ''Vintage Wines'' Little, Brown 2002 p. 344 {{ISBN|0-15-100704-7}}.</ref>

More common aging periods for Riesling wines would be 5–15 years for dry, 10–20 years for semi-sweet and 10–30+ for sweet versions.<ref>[http://www.rieslingreport.com/pdf/RR13-CellaringRiesling.pdf Riesling Report issue #13 March/April 2002, pp. 8-13: ''The Rewards of Cellaring Riesling''] {{Webarchive|url=https://web.archive.org/web/20171204182221/http://www.rieslingreport.com/hdOOk/pdf/RR13-CellaringRiesling.pdf |date=2017-12-04 }}.</ref>

=== Petroleum notes in aged Riesling wines ===
On release, certain Riesling wines reveal a striking petrol note<ref name="O. Bird petrol">{{Cite book | author = Owen Bird | title = Rheingold - The German Wine Renaissance | publisher = Arima Publishing | date = 2005 | pages = 90–97 | isbn = 978-1-84549-079-9}}</ref> (''goût de pétrole'' in French) that is sometimes described with comparisons to kerosene, lubricant, or rubber. While an integral part of the aroma profile of mature Riesling and sought after by many experienced drinkers, it may be off-putting to those unaccustomed to it, and those who primarily seek young and fruity aromas in their wine. The negative attitude to petrol aromas in young Riesling, and the preference for fruitier young wines of this variety, seem more common in Germany than in Alsace or on the export market, and some German producers, especially the volume-oriented ones, have even gone so far as to consider the petrol notes a defect which they try to avoid, even at the cost of producing wines that are less suited to extended cellar aging. In that vein, the German Wine Institute has gone so far as to omit the mentioning of "petrol" as a possible aroma on their German-language [[Wine Aroma Wheel]], which is supposed to be specially adapted to German wines, and despite the fact that professor [[Ann C. Noble]] had included petrol in her original version of the wheel.

The petrol note is considered to be caused by the compound [[1,1,6-trimethyl-1,2-dihydronaphthalene]] (TDN),<ref>{{cite journal | author = P. Winterhalter | title = 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) formation in wine. 1. Studies on the hydrolysis of 2,6,10,10-tetramethyl-1-oxaspiro[4.5]dec-6-ene-2,8-diol rationalizing the origin of TDN and related C13 norisoprenoids in Riesling wine | journal = Journal of Agricultural and Food Chemistry | date = 1991 | volume = 39 | issue = 10 | pages = 1825–1829 | doi = 10.1021/jf00010a027| bibcode = 1991JAFC...39.1825W }}</ref> which during the aging process is created from [[carotenoid]] precursors by acid [[hydrolysis]]. The initial concentration of precursors in the wine determines the wine's potential to develop TDN and petrol notes over time. From what is known of the production of carotenoids in grapes, factors that are likely to increase the TDN potential are:<ref name="O. Bird petrol"/>
* Ripe grapes, i.e., low yields and late harvest
* High sun exposure
* Water stress, which is most likely in regions which do not practice [[irrigation (wine)|irrigation]], and there primarily in certain dry vineyard sites in hot and dry years
* High acid content
These factors are usually also considered to contribute to high-quality Riesling wines, so the petrol note is in fact more likely to develop in top wines than in simpler wines made from high-yielding vineyards, especially those from the New World, where irrigation is common.