Optimum Mash Ph At Room Temperature

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Yorg

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A google gave me conflicting information.
So:
If I cool a sample of my mash to get it to room temperature, or within the automatic temperature compensation range of my Ph meter, is the Ph I want to see 5.2-5.3 or 5.5-5.6?
 
I'd hazard a guess at 5.2, since there is a buffering additive specifically made for mash brewing designed to give you a mash ph of 5.2

Palmer in 'How to Brew' says optimum mash pH is 5.1-5.5 pH.
 
Mash ph is outlined fairly well in palmer's book- different enzymes have slightly different optimum ph ranges.
 
I can see the confusion as a lot of text don't make it clear as what temp the ph was taken and when your working in such a narrow range it can make quite a difference the .35 ph higher at room temp compared to the mash temp ph.
It not only measures higher at room temp the ph is actually higher, the optimal ph ranges are ussually given at mash temp(so the actual ph) however so for optimal mash ph of say 5.3 this would read about 5.7 at room temp.
Pretty much what ever the reading at room temp take of .3 and that is the actuall mash ph, so at cooled wort temp you should be reading 5.4-5.7 etc which would be 5.1-5.4 at mash temp.

Clear as mud?
 
So:
If I am reading 5.5-5.6 in my cooled sample I'm right in the zone?

That's my reading of it.

In which case, if peple are using test strips, which presumably cool down very quickly, what reading should they be looking for?????
Does the strip remember the colour at the temperature it was dipped, or does it shift its reading as it cools, meaning that a reading of 5.2 as its sitting on the bench is actually too low??
 
So:
If I am reading 5.5-5.6 in my cooled sample I'm right in the zone?

That's my reading of it.

Thats it.



In which case, if peple are using test strips, which presumably cool down very quickly, what reading should they be looking for?????
Does the strip remember the colour at the temperature it was dipped, or does it shift its reading as it cools, meaning that a reading of 5.2 as its sitting on the bench is actually too low??

Good question, but even with precision narrow range strips its hard to get accurate to within .2 readings anyway, I have some and just use them to say yeah its not way high. As far as change in colour once it has cooled its almost too hard to tell because I haven't noticed it.
Is the colour set and stays the same who knows, maybe I'll do a test and measure something at mash out temp then cool it too very cold and see if I get a colour change because at these temperature differences the ph would change up to more like .5.


I'am sure someone else here might know more about how these strips work.
I have this link which talks about the differences between strips and a meter.
Also some good ph info on that site.

Get one of these and that saves all the confusion.

http://www.craftbrewer.com.au/shop/details.asp?PID=952

Chappo
Thats just a device that gives you a number and does nothing to help with confusion about what temp the ph is quoted at in any given text and what the number SHOULD be at any given temp.
 
Thanks Jayse.
Yes it would be interesting to know what your strip test says. Please let me know, as I have seen off two Ph meters - the last one was exactly the one suggested above, which only lasted less than a year - and I'm wondering about strips.
Quite tired of crappy inaccurate digital devices.

With all the stress on getting into an acceptable zone, its puzzling why this is not a settled well understood peice of home brewing knowlege.
 
With all the stress on getting into an acceptable zone, its puzzling why this is not a settled well understood peice of home brewing knowlege.
Yorg,

If you don't wish to worry get some of the 5.2 stabilser (starsan product), worked well for me and many others...just dump in required amount into mash and your good to go..no addition to sparge water required either.

Since going to the ANHC and sitting through water chemistry with the guru himself, I've since moved on to adjustments and using the above suggested pH meter.

Jayse, the pH meter Chappo suggested is temp corrected (it has a temp probe included) and pH displayed is what it is as long as you stick it in a solution within it's range. Mine is 0-50 degrees.

Cheers

PB
 
Jayse, the pH meter Chappo suggested is temp corrected (it has a temp probe included) and pH displayed is what it is as long as you stick it in a solution within it's range. Mine is 0-50 degrees.

what ever the temp of the sample it still needs to be adjusted for the temp of the actual mash if they are not both the same, i gather it gives you a temp reading aswell.

however this so called temp correction works anyway thats not what were talking about, were talking about the fact if you take a reading at room temp it will read .3 higher than mash temp. Temp correction just makes it so your meter can actually take a reading at mash temp without having to cool the sample, how well that works is well..................
 
Woah there. I'm confused again.
So, assuming the ATC works well, the word "compensation" suggests that it is giving a 'corrected' reading.
For example, taking a sample and measuring it at the extent of its range of, say 50C, this suggests that the meter is giving a reading AS IF the sample was being measured at room temp (or whatever it is 'compensating' to in its spec sheet.)
If this is correct, it can't possibly know that we are interested in, for example, 66C.
This means that the way to use the meter is to cool the sample to within its compensation range, take the reading, and add .3 to get the Ph at mash temp - the one we are interested in.

Correct?
 
Your pretty much spot on there I think but I would go the other way with the 'assuming' and assume the compensaton doesn't work well, if you think about it its gotta work better taking the compensation part out of the picture and just take the reading with a room temp(25c) sample.
I am sure some people will argue there is nothing wrong with the ATC.
The way I think the compensation works is it is giving you a reading as if the sample was at room temp(or within a range?) no matter what the temp of the actuall sample is, so for mash PH you have to subtract .3 from it.
So for a ph of 5.2 the meter should be reading 5.5, I am pretty sure some people are not taking this into account.

So yes I think your right, the best way to use it would be to cool to room temp for reading, but its minus .3 for mash temp not add as you posted (i think you got that sorted just made a mistake in your posting).
 
Your pretty much spot on there I think but I would go the other way with the 'assuming' and assume the compensaton doesn't work well, if you think about it its gotta work better taking the compensation part out of the picture and just take the reading with a room temp(25c) sample.
I am sure some people will argue there is nothing wrong with the ATC.
The way I think the compensation works is it is giving you a reading as if the sample was at room temp(or within a range?) no matter what the temp of the actuall sample is, so for mash PH you have to subtract .3 from it.
So for a ph of 5.2 the meter should be reading 5.5, I am pretty sure some people are not taking this into account.

So yes I think your right, the best way to use it would be to cool to room temp for reading, but its minus .3 for mash temp not add as you posted (i think you got that sorted just made a mistake in your posting).
Quite right. Look for a reading of 5.5.
I am prepared to bet money on lots of people being confused about this.

Cheers.
 
I am prepared to bet money on lots of people being confused about this.

Yeap same, I am also willing to bet there are some not so much confused but, for the want of a better less offensive word, ignorant to the fact that this is even the case.
 
It is a confusing subject, not least because brewing literature, even commercial brewing literature, never seems to specify the temperature at which mash pH is taken, so we assume mash temperature, possibly incorrectly.

One thing is certain though, is that it is incorrect to assume that a temperature-compensated pH meter compensates for differing pHs at differing sample temperatures. It does not. It only compensates for the effects of temperature on the pH probe / electrode itself. The reading it gives is the true pH at the measurement temperature. It is not easily possible for a pH meter to compensate for solution temperature because different types of solution are affected to a greater or lesser extent by temperature, and ordinary pH meters have no way of knowing what is being measured.

Another thing is that it is a possibility that the often-quoted figure of 0.35pH units difference is taken from generalisations on the interweb applicable to neutral water. However, solutions of high pH are affected much more greatly by temperature than solutions at low pH. As mash pHs are relatively low, the temperature effects are less than the generalistion.

In the wider scientific world it is usual for quoted pHs to be normalised to 25C, irrespective of the temperature at which the measurement is actually taken. 25C is the temperature at which the dissociation constants are given in scientific data, and is the temperature at which pH meters and buffer solutions are calibrated. Neutral water has a pH of 7 only at 25C.

Whether or not mash pH is specified at 25C, I really don't know, but it should be. The difference between room-temperature and 25C is insignificant. The higher the temperature of measurement the greater is the potential error.

Indeed, when I contacted a (British) pH-paper manufacturer as to why their papers gave different readings to a pH meter, I was told that pH papers indicate the pH at 25C. It did not actually answer the question because they both still gave different readings at 25C.

I have done several comparisons with pH papers of mash pH at 66C and 25C and I cannot detect any difference.

Even so, I doubt if anybody could detect a difference in beer if the mash pH was, say 0.2pH out, so even if my pH meter was still working, I would not be too concerned about temperature.
 
OK, great post Obidiah.

So the strips you've used seem to read the same, albeit with the assumption that they are a couple of points here or there, regardless of temperature being room or mash.

This still leaves the question I'm really wanting to get to the bottom of.
What should the reading be on my Ph meter, if I cool my sample to within its ATC range, if the mash I've just measured (which is mashing away nicely right next to me at say 65C), is right in the middle of the desired ph zone?
 
At 20 degrees optimal pH is 5.5 to 5.8, at mash temperatures it is 5.2 to 5.5. In both cases the lower end of the range is better. The literature is not particularly clear about this.

While pH is important, in most cases it is not a problem with paler styles because of, typically, soft water, and the buffering systems operating in the mash. The mash pH will tend to end up in the preferred range anyway. Nonetheless, small additions of calcium sulphate, calcium chloride, or acid malt will drop the mash pH towards the lower end of the range. In some styles a mineral character is required.

Automatic temperature compensation (ATC) compensates for variations in the working of the meter caused by heat. With ATC the reading given is the pH at the temperature of the sample, it does not give a reading adjusted to show the value at a standard reference temperature. Even with ATC, high temperatures are still rough on the probe.

In any case, for most hand-held pH meters with ATC the recommended maximum temperature is 50 degrees so they won't give an accurate reading at mash temperatures. Much better to cool all samples to 20 degrees, especially if you want to follow the changes in pH through mashing, sparging, boiling and fermenting.

Pat

Absolute Homebrew
 

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