I checked the titratable acidity (TA) of my cherry mead the other day, and something didn’t add up. Over six months, three measurements, and two acid additions (totaling 2.6 g/L) the TA fell from 6 to 5.5 g/L.
The most obvious explanation is that I goofed up the titrations. As I added more acid, the TA should have risen, so if the first measurement was accurate, then the second was low by 2.1 g/L (should have read 7.3 instead of 5.2), and the third was low by 3.1 g/L (should have read 8.6 instead of 5.5). I did three titrations that day using the same procedure, with the same chemicals and with the same equipment. I got “good” results from the other two titrations, and by that I mean consistent with my predictions and with past measurements. So maybe this measurement was accurate and the previous two were off.
That would mean the first was too high by 3.1 g/L (should have read 2.9 instead of 6) and the second by 1 g/L (should have read 4.2 instead of 5.2). A 1 g/L error on the second measurement is possible, because I’m measuring the sample and the sodium hydroxide with a syringe that I think is accurate to 0.5 ml, and that would mean only one large anomaly. Everyone makes mistakes, and maybe that just wasn’t my day.
Was the TA really that low? Well, I haven’t got a time machine handy so I can’t redo the test. My wildflower mead, from A Simple Mead Recipe fame, had an initial TA of 3.5 g/L, which isn’t much higher than 2.9, so that fits. Also, that was back when I had started doing titrations, so I might not have had the hang of it yet. I’m chalking this up to one bad measurement – the initial 6 g/L was really about 3.
Mystery solved!