According to Jasper Morris of Morris & Verdin, London wine merchants, 'riesling is the most unsaleable grape variety of all'. And yet the riesling grape, or rhine riesling, is without doubt one of the world's great varieties. 'Unbeatable quality, ludicrously unfashionable,' says the wine authority Jancis Robinson. Hugh Johnson, of World Wine Atlas fame, is another advocate.
Riesling can produce a spectrum of aromas and flavours - of flowers, spices, lemons, limes and apples. It can be the most long-lived of whites, ageing gracefully into wines of honeyed texture and subtle nuances, including a strangely alluring reek of the petrol station.
Admirers point to the fact that riesling is normally fermented in stainless steel. Unlike chardonnay, it does not need new oak to bring out its best. The refreshing acid-drop bite helps it retain its aromatic character and youthful fruitiness. But that higher acidity can make it a more austere and demanding wine.
Riesling is a versatile grape, but in some ways this has worked against it. It can range in style from bone-dry to lusciously sweet, from feather-light to rich and full-bodied. Riesling lovers know that a light, fruity style is best appreciated as an aperitif or on its own; a fuller, drier one is better with food. For newcomers the range can be quite baffling.
More fundamental is the widespread misapprehension that riesling is necessarily sweet. Of course, it can be: the reputation of classic German riesling stems in large part from the rich styles made from grapes affected by botrytis cinerea - noble rot - or frozen to intense concentration on the vine.
But the appeal of genuine fruit sweetness has spawned a host of imitators. Through liebfraumilch and inferior varieties carrying the riesling name, notably laski riesling (also known as riesling italico, welschriesling and olaszriesling), the aristocratic rhine riesling has been badly contaminated by sugary imposters.
Sales techniques have been deployed to overcome the debased image. 'Laski riesling' is no more, having been obliged by EC bureaucrats to adopt the risible name of 'rizling'. Australia's Wynns, among others, has changed its bottle shape from the German flute to a round-shouldered burgundian. Others have come up with the riesling friendly sales-pitch of calling the wine Dry White.
All well and good, but cosmetic changes designed to shield riesling from public view, as if it were some hideous monster, neither inspire confidence nor do much for longer-term prospects.
In London recently, Stuart Pigott, an authority on riesling, held a tasting of top wines from the 1990 vintage chosen by him to represent the pinnacle of dry riesling quality. There were 33 wines, 12 each from Austria and Germany, and nine from France. Since the white wine cultures of Austria and France are fundamentally dry, it was to be expected that their wines, from the Wachau and Alsace respectively, would do well.
Andre Kientzler's Grand Cru Geisberg, Schlumberger's Grand Cru Kitterle and Marcel Deiss's Grand Cru Schoeneburg were the stars of Alsace. Austria produced its fair share of superb rieslings, including perhaps the best of the tasting, F-X Pichler's majestic Durnsteiner Kellerberg 'Smaragd' (sadly Pichler, like most top Austrian wines, is unavailable in the UK).
One of the eye-openers was the quality of the German dry rieslings. Among other outstanding wines, Heyl zu Herrnsheim's Niersteiner Brudersberg Spatlese Trocken and Muller-Catoir's Gimmeldinger Mandelgarten Spatlese Trocken excelled. In the case of Germany, as spiritual a home to the rhine riesling as it is to the Ring of the Nibelungen itself, here was clear proof that high quality dry riesling has been integrated into the mainstream along with the genuine sweeter styles.
In the UK, however, while a limited market exists for the classic German riesling, the price-conscious mass-market predilection for cheap sweet lieb and the like is hard to budge.
Perhaps the New World can help. Rieslings from its warmer climates make up in flavour and price what they lack in delicacy and subtlety. Cooler regions in Australia and California are well suited for the production of affordable and approachable rieslings. Colder areas, such as New Zealand (and, to an extent, Washington state and Canada), seem almost indecently suited to produce good quality rieslings in dry, off-dry and sweet styles.
It would be a dreary world if riesling were to fall style victim to any single prevailing view of what it ought to be. As it begins to shed its poor image - a long, slow process - and wine drinkers learn to appreciate its quality and versatility, riesling's very difference from chardonnay will stand it in good stead as a quality alternative. Whether the wine-drinking public wants it enough to bring it into the mainstream remains to be seen.
BEST OF THE BUNCH
Montrose Rhine Riesling 1990 ( pounds 3.99, Oddbins). Full- flavoured, pungent, 'petrolly' Australian riesling.
Turckheim Alsace Tradition Edelzwicker 1992 ( pounds 4.95, Thresher, Wine Rack, Bottoms Up). Traditional blend of riesling, pinot blanc and muscat, with a floral, appley fragrance, delicately spicy fruitiness and nicely dry finish.
Erdener Treppchen Riesling Spatlese ( pounds 5.95, Waitrose). Classic, light Mosel riesling with typical 'kerosene-like' aromas and delicate, mature, off-dry fruitiness.
Freinsheimer Goldberg Riesling Spatlese Halbtrocken, Lingenfelder ( pounds 6.99, Oddbins). On the dry side of off-dry, honeyed riesling with soft acidity and clean finish.
Riesling Kabinett Anton Wober 1991 ( pounds 6.11, by the case, Penistone Court Wine Cellars, Sheffield; 0226 766037). Aromatic Austrian riesling with superb intensely flavoured peachy fruitiness. A bargain.
1989 Renaissance Riesling ( pounds 6.90, Adnams, Southwold, Suffolk). California riesling with full-bodied, citrus fruitiness.
Henschke Riesling 1990, Eden Valley ( pounds 6.94, Lay & Wheeler, Colchester; 0206 764446). Benchmark cool-climate Australian dry riesling, floral, exotic; will develop well.
Charles Schleret Alsace Riesling 1990 ( pounds 7.99, Lay & Wheeler). Delicate citrus fruit fragrance, a refined, fruity but dry Alsace riesling, showing maturity but no sign of age.
Grand Cru Brand Rangen de Than 1990, Zind-Humbrecht ( pounds 16.49, Wine Rack). Floral fragrance and rich, exotic ripe fruit, with the flavour and class for its high price.