Low mash pH

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guypettigrew
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Low mash pH

Post by guypettigrew » Tue Nov 19, 2019 11:49 am

Today's brew is 5kg Maris Otter, 400g crystal malt and 100g chocolate malt, mashed in 14l liquor.

After adding CRS the mash liquor alkalinity was 44 ppm.

The mash pH at about 20 minutes was 5.1. The lowest I've ever had. Hopefully not too low to make good beer though!

Bearing in mind the amount of crystal and chocolate malts, should I have got the mash liquor alkalinity higher, say 50ppm?

Guy

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Re: Low mash pH

Post by Jocky » Tue Nov 19, 2019 2:53 pm

All things being the same with the next beer I would suggest backing off the acid amount you used to leave an extra 20-30ppm residual alkalinity (so aiming for 65-75ish).

Also important to taste the beer and make notes on how you find it, both this and the revised version.
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Re: Low mash pH

Post by guypettigrew » Tue Nov 19, 2019 6:35 pm

Jocky wrote:
Tue Nov 19, 2019 2:53 pm
All things being the same with the next beer I would suggest backing off the acid amount you used to leave an extra 20-30ppm residual alkalinity (so aiming for 65-75ish).

Also important to taste the beer and make notes on how you find it, both this and the revised version.
Wow, 65-70 ish. Seems high. Is that what you aim for with a dark ale? For my lighter ales I go for about 15-20 and get a mash pH of about 5.4.

Means the effect of the crystal and chocolate malt must be greater than I expected.

The mash efficiency still came out at about 95% (using Graham Wheler's calculator), so perhaps thigs weren't too awful.

Guy

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Jocky
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Re: Low mash pH

Post by Jocky » Tue Nov 19, 2019 11:10 pm

Well if you are out by that pH I think you would need a bit of a step change.

It’s also a fairly small change to make - an 18ppm change is 1 ml less CRS/AMS per 10 litres of liquor.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.

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Eric
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Re: Low mash pH

Post by Eric » Wed Nov 20, 2019 12:16 pm

The influence of crystal malt on mash pH is frequently underestimated and can be much more than dark kilned malts and grains. Your recipe has approximately 9% of grist that in themselves would mash at a lower pH than would be desirable. The recipe will be somewhat similar in terms of pH to Dave Line's 70/20/10 grist for Guinness where the 20% flaked barley has the effect of raising pH more than pale malt, with only the 10% roast barley pulling pH down.

All that said, I'd not be in the least concerned about the finished beer in this instance. Been there, done that and enjoyed the result.
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Kev888
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Re: Low mash pH

Post by Kev888 » Wed Nov 20, 2019 1:32 pm

Yes, I agree with the above - 44ppm alkalinity is on the low side, so I think the pH results are very likely to be genuine. FWIW that would be more the kind of level I'd use for normal bitters, as this recipe has rather more crystal and dark grain I'd go with Jockey's suggested range - probably the higher end (or maybe even more).

That should get you much closer to target, but if you want to be certain with a new recipe then I sometimes find it useful to do a mini mash first. It only takes a short time, since you just need to mash a small (representative) portion of grains and liquor for say 10-15mins; one needn't do a full mash (or boil) unless you want the wort for a starter or something.

pH 5.1 is pretty low, assuming that was at room temperature, but as Eric I'm sure most of us have been there (I certainly have) and it will still make decent beer. These days I tend to aim a bit higher than I once did, since (I now believe) the often repeated range of pH 5.2 to 5.4 was originally taken from mash temperature readings, and should be more like pH 5.4-5.8 for standard room temperature ones. Which is also helpful if one then under-shoots.
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Re: Low mash pH

Post by guypettigrew » Thu Nov 21, 2019 9:01 am

Thanks for the input gents. Appreciated. Looks like I need to revise my target alkalinity figures upwards.

To date I've been working on 15-20 for very pale beers (Maris Otter, Vienna and perhaps caragold); 20-25 for middling colour beers (MO, Vienna and pale crystal) and 45-50 for darker beers (MO, crystal, chocolate and black malts).

Usual mash pH is 5.4-5.5 for the first two. I don't make darker beers very often, just fancied it this week.

Suggestions as to appropriate alkalinity levels for these types of beers would be very welcome.

Guy

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Re: Low mash pH

Post by Kev888 » Thu Nov 21, 2019 10:39 am

It is all very general, but I would consider normal bitters of reasonable colour to want around 40-50ppm alkalinity, which seems to tally with what you think of as darker beers. Beyond that, a mild might want another 10ppm, modest porters might be 60-80ppm, darker porters and stouts might be around 100ppm or more.

But each recipe is different and colour isn't an exact guide by any means, so these are just initial starting points that you might adjust up or down - e.g. based on experience of similar recipes or tests with a mini mash.
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Re: Low mash pH

Post by Jocky » Thu Nov 21, 2019 10:42 am

80-120ppm for stouts, but colour really is only an approximation - it very much depends upon the amount of crystal and roast malt in the grist. I like a lot.
Ingredients: Water, Barley, Hops, Yeast, Seaweed, Blood, Sweat, The swim bladder of a sturgeon, My enemies tears, Scenes of mild peril, An otter's handbag and Riboflavin.

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Re: Low mash pH

Post by Cobnut » Thu Nov 21, 2019 12:33 pm

I'm still very new to the whole "measuring pH" thing. I bought one of these recently https://www.ebay.co.uk/itm/392252990733 (I think someone on here said they'd had good experience with it) together with bottles of pH 4 & 7 calibration solutions.

I used it "in anger" at the weekend for a 100% pilsner Kolsch and it told me that the mash pH (at mash temp) was approx. 5.05.

I'd "adjusted" the local very hard water using CRS based on previous adjustments to c.20-30 ppm residual alkalinity, but must confess I didn't test the resultant water.

It is fermenting as we "speak" so we'll see how it turns out.

I'm thinking there's a load of variables here, many of which I have not controlled very well, but given that I have simply adjusted residual alkalinity before and have been generally happy with my beers, I'm still unsure what I'm gaining from measuring pH. Especially considering all the conflicting material I have read around this topic!

I have a desire to take my beers to a higher standard, and received wisdom tells me pH measurement should be part of the process, but I'm still not sure exactly how to go about a) measuring accurately; b) understanding what it is telling me; c) using the readings to adjust/improve my process.

ho hum!
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Re: Low mash pH

Post by PeeBee » Thu Nov 21, 2019 4:51 pm

Cobnut wrote:
Thu Nov 21, 2019 12:33 pm
… I have a desire to take my beers to a higher standard, and received wisdom tells me pH measurement should be part of the process, but I'm still not sure exactly how to go about a) measuring accurately; b) understanding what it is telling me; c) using the readings to adjust/improve my process. …
pH adjustments are an interesting "side-line" in beer brewing, but you've done right leaving it as a "next step" to create beers to a higher standard as pH isn't a panacea for any of your brewing problems. pH adjustments cannot make a bad beer good, but it might make a good beer a bit better. Not bothering with it still allows you to create decent beer, messing about with it and messing it up can create awful beer. Worrying about it and taking your eye off far more important aspects of brewing will also create awful beer (which then gets blamed on the water or a duff pH meter). More people taking up this hobby need to take heed of this instead of whinging about it while repeating the same water/pH unrelated foul-ups; there is the saying; "don't run before you can walk".

But, assuming you "walking just great and want to take some steps at a run":

a) measuring accurately:
Cool your sample (15-20C) before popping in a meter. You can compensate for warm samples, but hot samples is trashing your pH probe and you lose accuracy in future usage.

Check calibration if not done so for a couple of weeks. Calibration will wander. Recalibrate if necessary. Recalibration will get trickier; when it starts being a pain, change the meter. Eventually it will become impossible to recalibrate so bin it! Some probes last for years, some for six months: It's a bit of a lottery.

The linked meter has single point calibration: Aim to adjust the two calibration liquids to fit between the labelled values (pH 4.0 and probably 6.9, not 7.0? E.g. you might have to calibrate them to read 4.1 and 6.8?), so the pH5 to 6 range should be good. Expensive meters, and even cheap pen type these days, may have 2 or 3 point calibration to make it easier and more accurate over a bigger range.

b) understanding what it is telling me:
Firstly, see that second decimal digit? Ignore it! Or perhaps round it to the nearest single decimal digit. They just aren't that accurate, unless you fork out obscene amounts of money.

pH doesn't directly inform you how much of something (hydrogen ions) there is, but more how the salts "buffers", or "resists change of", those ions. So you seem to have fairly alkaline water (judging by your use of CRS) with plenty of buffering power. I have very soft water with low buffering: I can add 1/2 millilitre of 81% Phosphoric Acid to 60L of pH8 tap water, and the pH drops to <6. I guess your water is around 8? Imagine what the same acid addition would do for you.

Which also illustrates: The pH of your tap (source) water is meaningless.

c) using the readings to adjust/improve my process:
You were getting very close there! Use the readings to improve your process (next time), not adjust your current (today's) process. The latter results in either self-deception or madness (if you don't fall for the self-deception)!

Have fun!


I've gone on a bit there. Got carried away! There's plenty more to learn, I've just tried to set the boundaries because you can get utterly lost in this subject, as many have, yet not improve your beer one jot.

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Kev888
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Re: Low mash pH

Post by Kev888 » Thu Nov 21, 2019 6:20 pm

Cobnut wrote:
Thu Nov 21, 2019 12:33 pm
..but given that I have simply adjusted residual alkalinity before and have been generally happy with my beers, I'm still unsure what I'm gaining from measuring pH. Especially considering all the conflicting material I have read around this topic!
There are (as always) subtleties and pH has meaning through to the finished beer. But for me the first priority is simply to check that the mash pH is roughly where desired, not just where it was predicted to be. The predictions are only that, until tested in practice (as many things influence pH), and even with repeat brews it is always nice to check things are well, or else continue to refine total alkalinity adjustments.

If mash pH is as wished then not only does the mash itself benefit, with the enzymes consistently making the mix of fermentable sugars desired, but things are also more likely to fall into place down the line, too.

If it is just a bit out then there will be only subtle differences in the wort, at that level it is mainly about checking/improving consistency. If pH is significantly out then it might start to become more detectable, with either the alpha or beta enzymes working somewhat less well and so biasing the fermentability of the sugars. The fermentation might be affected and there can be more haze and stability issues.
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Re: Low mash pH

Post by Kev888 » Thu Nov 21, 2019 6:42 pm

Just by way of illustration Braukaiser has a chart showing not just temperature but also pH in relation to the various enzymes
Image

One may or may not agree with every detail on the chart, or the linked page, but IMO it gives the general idea. Without the hard edges on those colours it also usefully shows that the thresholds aren't very sudden so when people use specific numbers to indicate a range then it is to a degree a matter of judgement in drawing the pH compromise, which is partly why preferences vary.

(EDIT: hopefully it is obvious that this is Braukeiser's picture being referenced, with the link to his page too, but if any moderators think it might be a transgression then please remove it. This is a link to the picture within his page, which will no doubt serve)
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Re: Low mash pH

Post by guypettigrew » Thu Nov 21, 2019 8:40 pm

Very interesting. Looks like pH 5.6 at about 66°C is good. Also looks like my 5.1pH mash might produce a weird beer!

Guy

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Kev888
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Re: Low mash pH

Post by Kev888 » Thu Nov 21, 2019 9:05 pm

Well the fading colours are more illustrative than specific in that chart. Admittedly 5.1 is a little too low but it certainly isn't way out in no-man's land and so will still make fairly normal beer, especially if the temperature was normal too. Just a little different to how it would be if mashed as intended.
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