PH Adjustments

[Michael Burnley]

Been brewing a while but only just started to play with water treatment

I use beersmith to calculate the initial acid adjustments, my aim is to achieve a mash PH of 5.20

Just a few questions about PH testing and adjustments

1. How many minutes into the mash should I test the PH ?
2. Should I place the PH meter directly into the grist in the tun OR run a small sample off in order to cool it then test
3. If after testing the PH and I find it's a little high can I just simply add the appropriate amount of lactic acid to the tun


Many thanks

 

[Galena]

I am fairly new to water treatment myself but my understanding is

1) You should wait 5 - 10 mins before taking the mash pH, I always leave it 15 minutes.

2) If your meter is ATC then you can take a reading but it will not account for the change to pH that temperature causes, the standard for mash and beer pH is at room temperature 20-25C. Also taking a reading hot will shorten the life of your probe.

3)Yes you can, but by the time you have cooled your sample, tested the pH and worked out how much to add it is I believe (somebody correct me if I am wrong) probably too late for that to make any meaningful difference to your mash because the starch conversion happens fairly quickly so it may take too long to be effective.

What I do is calculate my additions using Brewfather, take my mash pH and if its a little out then I adjust for next time I make the brew. Of course a different recipe will be different so you need to keep good records. I have found though that even if mash pH is out a little I also take a beer pH reading at bottling and it has always been in the right range.

 

[mabrungard]

pH changes for quite a while during a mash. I've found that the 15 minute measurement is quite a way off of the terminal pH value. It takes about 45 minutes for the typical mash to reach what can be considered its terminal pH.

As mentioned above, placing the pH probe in the hot mash or wort is not an accurate way to assess pH and it shortens the life of the very thin glass bulb. Collect and cool your wort before measuring pH.

If you've formulated your mashing acid and mineral additions with a reliable software, I suggest that you refrain from chasing and correcting what you've measured as a pH. Measure the pH after about 45 minutes and learn from that result in order to figure out if your future adjustments need to be higher or lower in order to end up nearer your pH target.

 

[Galena]

pH changes for quite a while during a mash. I've found that the 15 minute measurement is quite a way off of the terminal pH value. It takes about 45 minutes for the typical mash to reach what can be considered its terminal pH.

Indeed, that is a very good point, though I believe pH changes slowly during the mash and I do wonder if you don't hit your target pH until 45 mins that you have not necessarily got the best conversion? Whereas if you hit it by 15 minutes then the enzymes will be fully active for the full length of the mash and the little it changes after this point will not be significant.
I have not tried checking but I will do a pH check at 15 and 45 on my next brew and make a comparison.