Blue Nun was developed between the wars as a medium-dry white. At its peak in 1984-85, annual sales reached 2 million cases, but fell to half that by the Nineties. Where have the defectors gone? Sainsbury's, whose liebfraumilch sales are down 5 per cent this year, says people are buying eastern European reds and drier Spanish whites.
I thought it was high time to shed a prejudice or two and do some blind tasting. As with the French non-affair with Piat d'Or, Germans do not drink liebfraumilch. How sensible, I thought, as I laboured through a dozen own-label examples from the supermarket and high street chains, varying in price from £2.12 at Tesco and Somerfield to £2.99 at Thresher and Oddbins. The two best-known, Black Tower and Blue Nun, £3.49 and £3.69 respectively, did not distinguish themselves.
In Waitrose's Liebfraumilch, at £2.49, there was a touch of the floral aroma and fresh grapiness you should expect from a decent liebfraumilch. Thresher's, £2.99, betrayed a modicum of mller-thurgau fruitiness. Otherwise, even allowing for the fact that the wines were all 1993s and perhaps past their "best", the overall level of confected sweetness masked any real life or fruit.
There was certainly nothing to which the word quality could legitimately be attached. Yet officially liebfraumilch is a quality German wine (QbA), a category which encompasses an immodest 95 per cent of the annual German vintage. The wine must come from the Rheinhessen, Pfalz, Nahe or Rheingau, contain not less than 18 grams per litre of residual sugar (in other words, be medium sweet), and consist of at least 70 per cent of the riesling, silvaner, mller-thurgau and kerner grapes. In practice, it is mostly made from the innocuous mller-thurgau and souped up with unfermented grape juice.
The German wine industry missed a golden opportunity to get to grips with the quality problem when the new German wine law came into force at the end of last year. Instead of making any radical change it merely tinkered with the laws, adding a new and confusing QbU, or "Qualittswein garantierten Ursprungs", a designation based on origin like France's appellation contrle.
Peter Hallgarten, a wine merchant whose German sales have declined considerably over 10 years, believes Germany needs to act fast to avoid the sort of crisis Spain found itself in during the Seventies: "Germany should distinguish its quality from its mass-market wines by taking liebfraumilch out of the quality category and raising the minimum ripeness qualification for quality wines."
Until Germany's producers get to grips with the problems, the relentless promotion of cut-price plonk will continue to obscure the fact that the country is capable of producing some of the world's most refreshingly delicate, fragrant and long-lived white wines. And not necessarily at fancy prices. Mostly made from the riesling grape, they range from the elegantly dry to the deliciously fruity at kabinett and sptlese level, and up the sweetness scale to rich, honeyed auslese and beyond.
A residue of loyalty remains among the older generation of wine drinkers brought up to regard Germany's traditional hocks and mosels as every bit as classic as top bordeaux and burgundy. But this is not a growing market. The cheap plonk image, not to mention some of the incomprehensible labels, make it far more difficult for anyone under 50 to appreciate such exciting new wines as those coming from producers such as Ernst Loosen, Kurt Darting, Rainer Lingenfelder, Toni Jost and Mller-Catoir.
Sadly, this is mirrored by the decreasing presence of fine German wines on lists and retailers' shelves in the UK. It has been suggested that Germany needs a juicy scandal like Austria's diethylene glycol dbcle of 10 years ago to sort itself out. The trouble is it already has a quality scandal and no one seems to want to do anything about it.
Wines of the Week
1983 stricher Doosberg Riesling Kabinett, Schloss Schnborn, £5.79, Somerfield. No great price for a sprightly 12-year-old, petrolly Rheingau riesling with plenty of tang and flavour.
1993 Graacher Himmelreich Riesling Kabinett, von Kesselstatt, £5.99, Asda. Perfectly proportioned floral mosel riesling with mouthwateringly crisp apple fruitiness and lemony bite.
1992 Bacharacher Schloss Stahleck Riesling Kabinett, Toni Jost, £6.99, Findlater, Mackie, Todd (John Lewis; 0181-543 0966). Classic new wave, refreshingly off-dry citrus tang.
1992 Graacher Himmelreich Riesling Kabinett, Max Ferdinand Richter, £8.11, Avery's of Bristol (0272 214141). Fragrant, off-dry mosel riesling with a delicate, feather-bedding of peachy fruit.
1986 rziger Wrz-garten Riesling Kabinett, Mnchhof, £5.79, Findlater, Mackie, Todd (John Lewis). Pungent, mature petrolly whiff over juicy, refreshing fruit from Robert Eymael's aptly named spice garden of rzig (or two bottles of liebfraumilch for same price).
1983 rziger Wrzgarten Riesling Auslese, Mnchhof, £7.95, Findlater, Mackie, Todd (John Lewis). Smoky, typically mature keroseney riesling aromas and a seductively honeyed fruitiness.
1987 Erbacher Marcobrunn Riesling Kabinett, Schloss Schnborn, £7.99, Victoria Wine. Straw yellow with an attractively complex nose, this is a mature, appley off-dry white with a surprising degree of concentration.
1992 Haardter Mandelring Scheurebe Sptlese, Mller-Catoir, £8.99, Oddbins. Richly flavoured, grapefruity off-dry white from one of Germany's great exponents of the scheurebe grape.