Just suddenly wondering where you guys get the mash sample that you are taking the pH of… do you scoop off the top, or run some cloudy liquid out of the drain of your mash tun, or what? And does it make a difference?
FWIW I take a cloudy sample out of the mash drain about 10 minutes into the mash, and I have lately been getting within +/- .2 pH pts of what Martin’s and Kai’s worksheets predict… but of course I always like to second-guess my SOP.
-red
I take my sample right after I vorlauf and let it come down to room temp.
Dave
I take mine around 15 or 20 minutes into the mash. I actually catch wort as it is recirculating in one of those stainless steel quart scoops used for decoction mashing. I run cold water over the outside of the scoop to bring the sample down to room temp (works pretty fast with the stainless steel). I dip my meter into that and presto!
Funny you should ask about this. One of my professional clients called me about their practices yesterday. They run a 20 bbl system and the tun doesn’t have rakes. They have a vorlauf pump, but had not been using it until the end of the mash. I recommended that they perform more recirculation during the mashing to improve the overall mixing of wort within the mash.
You can either move the media or move the liquid. Most homebrewers can mix their mash. But when you get into the 20 to 200 bbl range, its tough to mix the mash unless there is a built-in raking system. However, we RIMS brewers know that mixing is not necessary since we are moving the liquid.
In my opinion, you should sample for pH after you have mixed the mash well and vorlaufed any foundation water from the bottom of your tun. Remember, that water is part of the overall chemistry of the mash system. Your sampling should make sure that is well incorporated in the overall wort.
So better than taking a sample out of the drain, would be to dip into the main mash?
Please correct me if I am wrong gang…
I would say the main mash if you are not recirc’ing. If you can recirc you can pull it straight off the outtake. If you cannot recirc I would try to pull a relatively clean sample from the mash a few minutes after mixing well.
Like Martin said - you want a sample that is representative of the entire mash.
If you’re doing it after vorlauf, isn’t that too late to do anything about it since you are done mashing?
make notes and change it next time.
No, what I’m recommending is that a brewer perform an early vorlauf to fully mix the wort and any foundation water. This would be in the earliest stage of the mash. Then let it set and collect your pH sample.
I stir the mash and take as pH sample with a small 12 ml glass vial on a stiff piece of copper wire. I then also cool the sample in that vial using ice water.
If I’m confident that the mash pH is fine I may test the first wort.
Kai
Exactly. I have a two cooler gravity system so I’m not going to/don’t want to change much during the mash. I’m typically within a few tenths anyway, having good water.
Dave
Gordon Strong recommends taking your Ph at the beginning of your mash and reading AT MASH TEMPERATURE, NOT COOLING. Cooled sweet wort is going to read~.35 higher.
I check about 10 min. after mashing in. Since I have no foundation water in my cooler and I’ve thoroughly mixed the mash a few minutes before, I just run about 8 oz. out of the spigot into a metal cocktail shaker. That goes into a bowl of ice water and in 30 sec. to a min. of shaking it’s down to temp and I can take a reading.
I believe that the reading after cooling is the accurate one. On this I disagree with Gordon. I could be wrong…again…
No, unfortunately this is something that apparently Gordon did not understand. Always cool your wort to a somewhat consistent room temperature and perform your pH reading then. 5 or 10 degrees off of the typical room temperature in the 70’s F range is OK. The pH won’t vary enough to matter when you are that close.
The necessity to cool the sample is something I’ve never really understood.
If the change in pH with change in temperature is linear, why couldn’t you just adjust the mash temperature reading?
Also - if the above is feasible, would you calibrate your sensor at mash temp?
The main reason is that it’s bad for your probe.