Titratable Acidity: Mystery, Consistency, and too much acid

Cherry Mead: The case of the disappearing acid

Suppose you measure 6 g/L titratable acidity (TA), then add about 1.3 g/L of tartaric acid. After you let it sit for a while you’d expect a TA over 7, right? Me too. You certainly wouldn’t expect just a little over 5 (call it 5.2), would you? I didn’t either, but that’s what happened and that wasn’t the end of it. I’m talking about my cherry mead and after that 5.2 measurement, I added another 1.3 g/L of tartaric acid. When I checked again the TA stood at just over 5.5 g/L, not the 6.5 I was expecting. Over the course of six months, my starting TA fell from 6 g/L to 5.5 g/L as I added 2.6 g/L.

What happened? I don’t know, but a look at pH tells me that the additional acid was affecting the mead, even if I wasn’t detecting it in my titrations. While TA went from 6 to 5.2 to 5.5, the pH went from 3.56 to 3.39 to 3.13. I’m going to have to chew on this for a while. Got any theories? I’d love to hear them.

Honey Apple: Promising, but not ready yet

Compared with my cherry mead, the honey apple is a model of consistency. Yesterday’s measurements:

SG: 0.996, pH: 3.56, TA: 7 g/L

were exactly the same as on 11/15/07. This is reassuring and gives me a (false?) sense of precision. It’s not ready to drink yet; tasting it all I could think of was “tart and young.” The Lady of the House would only say that, yes, it was an apple wine or mead but refused to offer anything more. It’s clear with compact sediment, and the numbers look good, so I think I’ll rack without making any adjustments.

Tomato Wine: Young, tart, and bone dry

It tastes just as harsh as you’d expect it to from these numbers:

SG: 0.990, pH: 2.97, TA: 9- g/L

In addition to being tart, there is an unusual flavor that I wouldn’t recognize if I didn’t know I was drinking tomato wine. I’m not sure whether I like this tomato flavor or not – its hard to get past the harshness of this wine. The Lady of the House knew it was the tomato wine, even though I didn’t tell her. She made a face and said it was young and that there was “an acid thing” going on. This one needs some more time, and I need to neutralize some of the acid.

So, I’ve got a mystery to solve, some acid to neutralize, and some mead to rack. Time to hit the “save” button.



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2 thoughts on “Titratable Acidity: Mystery, Consistency, and too much acid

  1. Edwin Hoogerbeets

    Hi, I know this is an old posting, but I just found it with a search, and thought I’d answer your question about the “disappearing acid” in case you hadn’t already had some other ideas. This is possibly because of something like the common-ion effect. You are maybe adding acid that has a ion in common with something that is already in your wine, suppressing the dissociation of one or the other, and making it so that the ions are not titratable any more. That is, the base that you add during the titration cannot “use up” the ions from the acid because they are not available in solution to use. ie. The acid is there, but not measurable with a titration.

  2. Erroll Post author

    Hi Edwin,

    I remember learning about the common ion effect decades ago, but after all this time any memory of what it is or why it might be important is long gone – so thank you for explaining it. It makes me want to learn more about the composition of cherries, and brush up on my chemistry.

    Erroll

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