Riesling

Earlier, Riesling was sometimes claimed to have originated from wild vines of the Rhine region, without much support to back up that claim. More recently, DNA fingerprinting by Ferdinand Regner indicated that one parent of Riesling is Gouais blanc, known to the Germans as Weißer Heunisch, a variety that, while rare today, was widely grown by the French and German peasantry of the Middle Ages. The other parent is a cross between a wild vine and Traminer. It is presumed that the Riesling was born somewhere in the valley of the Rhine, since both Heunisch and Traminer have a long documented history in Germany, but with parents from either side of the Adriatic the cross could have happened anywhere on the way.

It has also been suggested, but not proved, that the red-skinned version of Riesling is the forerunner of the common, "white" Riesling.[13] The genetic differences between white and red Riesling are minuscule, as is also the case between Pinot noir and Pinot gris.

On release, certain Riesling wines reveal a striking petrol note[19] (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),[20] 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:[19]

• 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, 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.

Today Riesling is Germany’s leading grape variety, known for its characteristic “transparency” in flavour and presentation of terroir,[24][25] and its balance between fruit and mineral flavours. In Germany, Riesling normally ripens between late September and late November, and late harvest Riesling can be picked as late as January.

Two common characteristics of German Riesling are that they are rarely blended with other varieties and usually never exposed to oak flavour (despite some vintners fermenting in "traditionel" old oak barrels already leached). To this last item there is an exception with some winters in the wine regions of Palatinate (Pfalz) and Baden using new oak aging. The warmer temperatures in those regions produce heavier wines with a higher alcohol content that can better contend with the new oak.[26] While clearer in individual flavours when it is young, a German Riesling will harmonize more as it ages, particularly around ten years of age.

In Germany, sugar levels at time of harvest are an important consideration in the wine's production with prädikat levels measuring the sweetness of the wine. Equally important to winegrowers is the balance of acidity between the green tasting malic acid and the more citrus tasting tartaric acid. In cool years, some growers will wait until November to harvest in expectation of having a higher level of ripeness and subsequent tartaric acid.[27]

Before technology in wineries could stabilize temperatures, the low temperatures in winter of the northern German regions would halt fermentation and leave the resulting wines with natural sugars and a low alcohol content. According to local tradition, in the Mosel region the wine would then be bottled in tall, tapered, and green hock bottles. Similar bottles, although brown, are used for Riesling produced in the Rhine region.[28]

Riesling is also the preferred grape in production of Deutscher Sekt, German sparkling wine.

Riesling wines from Germany cover a vast array of tastes from sweet to off-dry halbtrocken to dry trocken. Late harvest Rieslings can ripen to become very sweet dessert wines of the beerenauslese (BA) and trockenbeerenauslese (TBA) class.

Riesling grapes growing in Alsace

Riesling is on record as being planted in the Alsace region by 1477 when its quality was praised by the Duke of Lorraine.[29] Today over a fifth of Alsace's vineyards are covered with Riesling vines, mostly in the Haut-Rhin district, with the varietal Riesling d'Alsace being very different from neighboring German Riesling.[30][31] This is partly from difference in the soil with the clay Alsatian soil being more dominately calcareous than the slate composition of Rheingau. The other differences come in wine making styles, with the Alsatian preferring more French-oriented methods that produce wines of higher alcohol content (normally around 12%) and more roundness due to longer time spent in neutral oak barrels or steel tanks. In contrast to German wine laws, Alsatian rieslings can be chaptalized, a process in which the alcoholic content is increased through the addition of sugar to the must.[32]

An Alsatian Riesling

In contrast to other Alsatian wines, Rieslings d'Alsace are usually not meant to be drunk young, but many are still best in the first years. Rieslings d'Alsace tend to be mostly very dry with a cleansing acidity. They are thick-bodied wines that coat the palate. These wines age exceptionally well with a quality vintage aging up to 20 years. This is beneficial since the flavours in an Alsace wine will often open up after three years, developing softer and fruitier flavours.[30] Riesling is very suitable for the late harvest Vendange Tardive and the botrytized Sélection de Grains Nobles, with good acidity keeping up the sweetness of the wine.

In addition to Muscat, Gewürztraminer and Pinot gris, Riesling is one of the acceptable varieties whose planting is allowed in Alsace grand cru sites.[33]

Gold lettering on collectible Sydney Opera House wine

In 1838 William Macarthur planted Riesling vines near Penrith in New South Wales.[34] Riesling was the most planted white grape in Australia until the early 1990s when Chardonnay greatly increased in popularity.[32] Riesling still flourishes in the Great Southern of Western Australia (in particular Mt Barker, Frankland River and Porongorup), and in South Australia in the Clare Valley, and particularly in the areas of Watervale and around Polish Hill River, and the cooler Eden Valley and High Eden. The warmer Australian climate produces thicker skinned grapes, sometimes seven times the thickness of German grown grapes.[26] The grapes ripen in free draining soil composed of red soil over limestone and shale, producing a lean wine that, as it matures, produces toasty, honeycomb and lime aromas and flavors. It is common for Australian Rieslings to be fermented at low temperatures in stainless steel tanks with no oxidation of the wine, followed by earlier bottling.[35]

Australian Rieslings are noted for their oily texture and citrus fruit flavors in their youth and a smooth balance of freshness and acid as they age. The botrytized Rieslings have immense levels of flavor concentrations that have been favorably compared to lemon marmalade.[36]

Riesling was first planted in New Zealand in the 1970s and has flourished in the relatively cool climate of the Marlborough area and for late harvests in the Nelson region. In comparison to Australian Riesling, New Zealand produces lighter and more delicate wines that range from sweet to dry.[37] Central Otago, the home of cool climate wines, has recently emerged as another area producing terroir driven Rieslings.

Riesling is the second leading white grape varietal after the indigenous Grüner Veltliner.[38] Austrian Riesling is generally thick bodied, coating the palate and producing a strong clarity of flavour coupled with a mouthwatering aroma. A particular Austrian Riesling trademark is a long finish that includes hints of white pepper. It flourishes in the cool climate and free-draining granite and mica soil of the Wachau region where Austrian wine laws allow for irrigation. With levels normally around 13% it has a relatively high alcohol content for Riesling and is generally at its peak after 5 years.[35] Austrian Riesling is not known for its sweetness and is mostly dry with very few grapes affected by botrytis.

A Riesling from the Columbia Valley AVA of Washington State

In the late nineteenth century, German immigrants brought with them Riesling vines, borrowing the name of Schloss Johannisberg to mark the plants' origin. "Johannisberg Riesling" became a semi-generic name for Riesling until an agreement between the U.S. and EU prohibited its use in 2006.[39] New York, particularly in the Finger Lakes region, was one of the earliest U.S. producers of Riesling. Plantings started to appear in California by 1857 and followed in Washington State in 1871.[35]

New York Riesling generally has a characteristic effervescent light body with a similarly light, mellow flavor. The wine can be dynamic though rarely robust, and ranges from dry to sweet. New York is also a notable producer of Riesling-based ice wine, although a large majority of New York Ice Wine is made from Vidal blanc and Vignoles.

In California, Riesling lags far behind Chardonnay in popularity and is not as commonly planted. A notable exception is the growing development of high quality Late Harvest dessert wines. So far, the Late Harvest wines most successfully produced are in the Anderson and Alexander Valleys where the weather is more likely to encourage the needed botrytis to develop. The Riesling that does come out of California tends to be softer, fuller, and having more diverse flavours than a "typical" German Riesling.

In the Pacific Northwest, there is a stark contrast in Riesling production. Although Oregon was once viewed as a promising destination for the grape, Burgundy-stylewines came to dominate, while in Washington, large producers such as Chateau Ste. Michelle spearheaded Riesling's growth.[40] Chateau Ste. Michille championed German styles and partnered with well-known German firm Dr. Ernest Loosen to create specialty wines such as the Eroica brand. With annual productions of over 2,000,000 cases a year, Chateau Ste. Michelle is the worldwide leader in the production of Riesling wines by volume. In 2007 Pacific Rim Winemakers, another Pacific Northwest winery and owned by Randall Grahm of Bonny Doon, has built the first wine facility in Red Mountain AVA dedicated completely to Riesling production.[41] Riesling from this area ranges from dry to sweet, and has a crisp lightness that bodes well for easy drinking. Often there will be an easily detectable peach and mineral complex

In Michigan, whose Old Mission Peninsula and Leelanau Peninsula AVAs (near Traverse City) are known for their ice wine, Riesling is a fairly common variety, in part on account of its suitability for that purpose.[42][43]

Riesling is grown in other regions as well, including colder parts of relatively warm states such as Oklahoma (where it has even been made into an eiswein[44]) and Texas.[45]

Riesling is also grown throughout all the regions in Ohio and is produced and sold at award-winning wineries across the state.

In Ontario, Riesling is commonly used for icewine, where the wine is noted for its breadth and complexity.[36] Niagara is a major producer of ice wine in general, putting it neck-and-neck with Germany. Late Harvest wines and some sparkling wines are produced with Riesling in Niagara but it is table wines from dry to off-dry that hold the largest share of production. The climate of the region is typically quite warm in the summertime, which adds a layer of richness in the wines. The founder of St. Urbanshoff in the Mosel, Herman Weiss, was an early pioneer in Niagara's modern viticulture, selling his strain of Mosel clone Riesling to many producers in west Niagara (these vines are well over 20 years old now). This clone and Niagara's summer heat make for uniquely bright wines and often show up in interesting dry styled versions. Many producers and wine critics will argue that Niagara's best offerings come from the Niagara Escarpment region, which encompasses the Short Hills Bench, 20 Mile Bench, and Beamsville Bench.

In British Columbia, Riesling is commonly grown for use in icewine, table wine, and sekt-style sparkling wines, a notable example of which is Cipes Brut.

In Nova Scotia, particularly in the Annapolis Valley region, Riesling is showing significant promise, being shaped by the warm summer days with cool nights and the extension of the growing season that is being observed. The Maritime climate combined with glacial soils contribute to the interesting expressions that are showing.

Riesling is also widely grown in Luxembourg (where it represents some 12% of the vineyard), Hungary, Italy, particularly Friuli-Venezia Giulia, Croatia, South Africa, Chile and Central Europe, particularly Romania and Moldova, Serbia, Kazakhstan and Uzbekistan.