When I measure pH in the cooled wort before pitching, I find that it is higher than it was when I measured it towards the end of the boil. It is maybe about as much as 0.2 higher. That's pretty annoying, and I don't understand why it should happen. One possible answer - which I actually find hard to believe - is that it's caused by the Supermoss I'm adding 5 minutes before end of boil.

Any thought on this?

NB. I always measure cooled samples.

 

Supermoss is carrageenan mixed with glucose (dextrose, corn sugar). I don't know what glucose will do to the pH of distilled water, but I doubt it would matter much in wort. It shouldn't be hard to test it anyway. Next brew I'll take a sample just before I add the Supermoss, then one at flameout, and finally one as I drain the kettle after cooling.

If it has got anything to do with the carrageenan, it's probably not the carrageenan itself. Maybe it's related to the effect of it's taking out proteins?

I'm not a chemist, but at times I really wish I were - or that I had one at hand that I could ask.

 

That sounds like a reasonable possible explanation, but I'm afraid it's wrong, as is my whole idea that carrageenan is the cause of what happens to my readings. I finally did find some reasearch on this, here: https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1995.tb00860.x . On p. 188: Preliminary experiments also established that addition of copper finings to wort did not significantly alter cold wort pH(TableI 1).

Searching the net, I found a few others posting questions about the same problem. No good answers, though most suggesting that there might be something wrong with the pH meter. I'm sure that's not the case here. I use the meter several times throughout the process, and when it doesn't give me any readings outside of what I would expect until that last one, I don't think there's any reason to suspect that it is something wrong with it.

I'm really not sure what to think. If this is a real problem, it's strange that it isn't recognized. But I guess most people don't take readings post boil. If you take a preboil reading, you should expect around 0,2 below that when the boil is done, according to theory. So why bother? Then it also seems to be a widespread belief that the yeast will take the pH down to the right level anyway. And if you read Palmer - which I generally think is a good idea - he tells you that the mash pH will set up the pH for the rest of the process.

I don't think any of these assumptions are correct. Monitoring pH as the brew progresses has taught me it's not at all that straightforward.

 

A late addition of chalk might cause something like this, as it's effect might be a bit delayed, but no, I haven't done that.

 

No, I have now ascertained that carrageenan does not raise pH, and I'm sure the glucose don''t. So there must be some other explanation.

Supermoss works fine for me. I add it just five minutes before end of boil, as newer research indicates that a longer boil will make processed carrageenan less effective. Irish Moss - which isn't processed the same way, but just dried, or so it seems - should be added 10 minutes before end of boil, according to the same source. (Sorry, I don't have that source now.)

 

It's nice to have it confirmed from others.

 

I'm rather perplexed. What happens in the mash is always very predictable, so it can't be my pH meter, because then I would get these strange readings during the mash as well. Oh well - as long as the beer tuns out OK ... but I would still very much like to know why it happens.