It’s often assumed that European rieslings have more acidity than New World versions, and this is one of the reasons the European “originals” are often considered superior. However, if you look at the facts, this turns out to be wrong.
Most winemakers prefer to measure acidity as pH instead of percentage, because pH tells them the intensity of the acidity. Of course, that’s what interests us wine drinkers: Is it too tart for me, or is it too flabby? The pH scale is easy to understand once you realize that pH 7 is neutral (e.g. distilled water); numbers above 7 belong to the realm of alkalinity (e.g. ramen noodles); and below 7 everything is more or less acidic (almost all foods and beverages). Most wines lie between 3 and 4 on the pH scale, whites tending towards the lower end of that range and reds towards the upper end. The lower the number the more intense the acidity.
Over the last two years, I’ve done a lot of travelling around Planet Riesling researching my forthcoming book on the subject, and I collected a slew of pH readings. For example, the wines of Schloss Johannisberg in the Rheingau, arguably the world’s most famous riesling producer, range in pH between 3 and 3.20. Klaus—Peter Keller in Rheinhessen told me his sought after dry Grosses Gewächs rieslings lie at the upper end of that range. Martin Tesch, who has gained a reputation for making high—acid rieslings at his Nahe estate, gave me a very similar figure for his bone-dry Riesling Unplugged.
When I started collecting figures for North American wines I got quite a shock. For example, the medium—dry 2010 Wallula Vineyard from Pacific Rim in Washington State is pH 3.15 and Hermann J. Weimer’s 2012 Dry Riesling from the Finger Lakes is only a shade lower—figures directly comparable with the top dry German rieslings! And yet, these turn out to be at the softer end of the range for North America, as demonstrated by the 2011 Corral Creek Vineyard Riesling from Chehalem in Oregon (an impressive wine from a difficult vintage): It clocks in at pH 2.83. Even bottled as a medium—dry wine, you really need to like acidity to enjoy drinking it.
And what is it about the semi—desert of Okanagan Valley in British Columbia that makes it home to what may be the world’s most acidic rieslings? I love the 2012 Riesling from Tantalus with its piercing—but—minerally acidity. The pH under 3 is the reason it tastes so dry in spite of 1.5% unfermented sweetness. The most acidic riesling I ever encountered is the off—dry 2012 Platinum from Cedar Creek in the Okanagan, with an astonishing pH 2.73. The only wines that sometimes match that figure are chardonnay base wines for Champagne, deliberately picked early to get that acid.
So far nobody can properly explain why Okanagan is the riesling acid champion. So it turns out that those acid hounds who bemoan the fact that German rieslings have become softer are right (up to a point). Maybe they need to take the rieslings from some regions in North America a lot more seriously if they still want that acid hit.