PH - WineSpeed - Karen MacNeil

PH

A measure of the strength of the relative acidity versus the relative alkalinity of wine (or any liquid) on a logarithmic scale of 0 to 14. The lower the number is below 7 (the neutral pH of water), the greater the relative acidity. Winemakers consider the pH of a wine in relationship to other factors (ALCOHOL, TANNIN, EXTRACT, and the like) to determine if the wine is in BALANCE. As grapes mature, plotting the change in the pH of their pulp is a way of determining ripeness.

What is Oechsle?

A. Austria’s version of Beaujolais Nouveau, made with spätburgunder (pinot noir)

B. A type of soil famous in Portugal’s Douro Valley, made of layers of minerals that retain heat well

C. Native Hungarian grape variety used to make Tokaji Aszú

D. Scale used in Germany to indicate the ripeness of grapes

Ok, the German was something of a dead give-away, and this wine question was a bit nerdy we admit, but Oechsle is a scale which measures the weight of the grape juice or must before, during, and after fermentation. Developed in the nineteenth century by the physicist Ferdinand Oechsle, the scale gives an indication of ripeness and potential alcohol. The ripeness categories (Kabinett, Spätlese, etc.) of traditional German wines are based on Oechsle levels that are specified for each grape variety and each wine region. Other sugar measurement scales used in winemaking around the world include Baumé, favored in other parts of Europe and Australia, as well as Brix, used in the U.S.

“….it’s not really just the chemistry that makes wine interesting or valuable. There’s a lot more behind the story of wine than chemistry. I know that might be disappointing for some chemists, but the reality is that people love wine. And people love wine not just because of the way it tastes.”

—Andrew Waterhouse
Professor of Viticulture & Enology, University of California at Davis

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