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Author, winemaker, and innovator in the wine industry
2 posts • Page 1 of 1
There are two causes of Hi pH / Hi TA. Their somewhat misleading names are “High Potassium” and High Malate”. Potassium isn’t a bad actor, but simply a measurable cation pairing with bitartrate, which is the real culprit.Tim Corliss wrote:In reading your book, I was trying to follow how this occurs and how to make adjustments. Let's assume you are a small winery without access to technology. How does this occur and what are the best remedies?
Hi pH / Hi TA means you have lots of titratable protons but few that are free. This is like a condition where you have lots of cops on the payroll but few on the street fighting crime. Wh cops are drawn to them just ere are they? In the doughnut shops! This can occur when there are really good doughnut shops that attract the cops (high malate) or just a whole lot of mediocre doughnut shops on every corner, so that the cops are drawn to them simply because of their numbers (high bitartrate / high K+).
If you are in a warm climate, chances are high potassium is your problem. It’s usually associated with very good fruit and is easily remedied in the winery by tartaric acid addition, preferably at the juice stage. This adds to the already high TA (titratable acidity), and this is pretty scary, so before you treat the tank, you try it on a lab scale to make sure it will work.
Say you’ve got 10 g/L TA and pH 3.9. You measure how much tartaric it takes to reach pH 3.6, the peak of the bitartrate curve. In this example, you might add 2 grams per liter, ending up at pH 3.6 and 12 g/L. (Don’t try half measures, as it will appear that it didn’t work when the pH comes right back up.) Then chill the bottle overnight, spin/settle/filter a few mls clear, and test the TA and pH. Typically you would end up with pH 3.6 and maybe 8.5 g/L and a whole lot of white powder. Perfect numbers. This works because you have lots of potassium lots of tartaric and you are at the peak of the bitartrate curve. Easy.
High malate is a much harder fix. It happens in cool climates, low ripeness and high acid varieties like Colombard, Picpoul Blanc and most hybrids. There are a number of ways of reducing malate. The two most effective for the small guy are a malate-consuming yeast or double salt precipitation.
I teach how to do all this in my Fundamentals of Modern Winemaking class which is running next week and available online. Check it out at Modern Wine Chemistry Fundamentals Online.