Problems with Mash Ph

[private4587]

When do people take the sample from the mash to obtain the Ph. I take mine after approx 10-15 mash time. My problem is that even though i get the Ph right in Bru'n water and i calibrate my meter(one of those yellow ones) using 6.8 & 4.1 solutions. the Ph i obtain once sample has cooled is often way lower than expected usually around the 3.5-4.5 mark. Any ideas where i am going wrong.

 

[Medlar]

This is exactly what happened to me on my last brew. I check mash pH at the same sort of time, and, without significant water treatment, I regularly get 5.3-5.37. This time I boiled out the calcium carbonate in the mash water first (hard water area), and attempted to 'adjust' the chemistry to suit my brew (still learning) . Wrong! I got a pH of 4.7, so added some bicarbonate of soda (all I had available) half teaspoon at a time until I got back to where I would have been if I hadn't mucked about in the first place. Lesson learned, but at least it was fixable, and the resulting beer seems to be turning out great anyway. There was a risk of too many sodium ions floating about using bicarb, but I seem to have got away with it. There are many more experienced people on here, but my understanding is you need to start with an analysis of your water (from your water company), and work out what, if anything you need to do. This will depend on what you intend to brew as your grain bill will affect mash pH. It seems all I really need to do for what I tend to brew is add some epsom salts for the Mg, and I will stick with this for now.

Someone's now going to tell me I was lucky to get away with it I suspect!

 

[Clint]

You were lucky to get away with that.*

*I know sod all really about water treatment.

 

[Medlar]

So, it would appear, do I!

 

[Slid]

I used the phase 1 "Noddy" guide to water treatment to make a simple cribsheet for what amount of Gypsum and Epsom salts to add to a short list of basic brew styles for my soft water.
So, it requires essentially nothing to brew a stout and about 3 teaspoons altogether for a Pale Ale.

The calculator on the forum is very easy to use and it is usually possible to get a good approximation of your water supply from your water company. You just plug in the numbers off that into the calculator for the listed beer styles. I have never bothered with pH, mainly because my water is just run-off from the hill I can see out the bedroom window. It's Winter Hill, the one near Bolton, with the TV mast. So the water is going to be fairly neutral, as it passes though no rock and few sheep.

 

[private4587]

I do have the water report from my supplier for what good it is, i also test before a brew for calcium and alkalinity using the the test kits recommended by Steve. All this is plugged into Bru'n water along with grain bill. I then choose brew style and jiggle additions to try and match these along with getting an approx Ph. But like i say I am not getting the result i expected

 

[Zephyr259]

I have a similar problem and tend to get a pH about 0.2 - 0.3 lower than predicted by bru'n water, I always aim for 5.4. Then I got 2 or 3 brews dead on in a row followed by another under. Trend seems to be based on crystal malt, if I don't use any then BW is spot on, as soon as I use some it's out. Poking the figures for a pale ale which had 7% CaraHell if I switched it to a roast malt in the grain bill tab then it matched my measurements. I tried this for the 80/- I brewed next, but it had about 18% crystal so I overshot and hit 5.6, added a bit of citric acid to bring it down and hit 5.3 which was good enough.

Long and the short of it that Bru'n water appears to underestimate the pH drop you get from crystal malts, probably gets more accurate the darker the malt.

 

[DrGMc]

Yep welcome to the fun of water chemistry in brewing (I've a doctorate in chemistry so at least I have a chance but it still hurts the grey cells).
Crystal malts behave differently from crystal malts regards the pH they generate from the malt - there is some good stuff on alchemyoverlord but its a bit (ahem) geeky.
Two factors to remember:
1) the enzymes in the mashing events have a pH profile
(in other words they work faster at a particular pH - although don't worry it doesn't crash but rather drops off either side and pH.

The main enzyme:
alpha- amylase from malted barley seems to have a pH optimum of 5.0-5.4 and interestingly the enzyme appears stabalised by calcium ions.
beta-amylase from malted barley seems to have a pH optimum of 5.5 (I'm sure +/- 0.2 would have minimal effect {maybe +/- 20% activity})


2) measuring pH is temperature sensitive ... for wort and mashes the actual pH can be 0.3 - 0.4 units lower at 65 oC (150 F) than it is at room temperature 20 C (68 F), or 0.45 if your brewing in a cold garage
As such most measurements are done at room temperature after letting the aliquot (sample) cool down {rather than burning fingers and swearing as the temperature drops during measurement}

There is of course lots more going on in the mash but as far as pH goes the above are at least two of the factors you need to know.

Hope it helps and geek hat is now off
Graham

 

[DrGMc]

When do people take the sample from the mash to obtain the Ph. I take mine after approx 10-15 mash time. My problem is that even though i get the Ph right in Bru'n water and i calibrate my meter(one of those yellow ones) using 6.8 & 4.1 solutions. the Ph i obtain once sample has cooled is often way lower than expected usually around the 3.5-4.5 mark. Any ideas where i am going wrong.

I take my measurement at the end of the "acid rest" (about 10 minutes at 40 oC).
During this rest period the enzyme "phytase" lowers the mash pH by cutting up phytic acid anywhere around 30–52 °C at pH 5.0-5.5 to release some phosphate ions.
Hope that helps explain why the pH can drop lower than you expected

 

[strange-steve]

I'm with @Zephyr259, the most likely answer is that Bru'n Water is underestimating the pH drop due to crystal malts, which is due to the fact that it's extremely difficult to accurately predict without knowing exactly all the parameters of the specific malts being used.

If this is happening consistently, then I would suggest simply aiming for a higher pH in Bru'n water to compensate, at least as a trial.

@DrGMc good to have an actual chemist on board
Curious, why do you use an acid rest?

 

[DrGMc]

plain

This is exactly what happened to me on my last brew. I check mash pH at the same sort of time, and, without significant water treatment, I regularly get 5.3-5.37. This time I boiled out the calcium carbonate in the mash water first (hard water area), and attempted to 'adjust' the chemistry to suit my brew (still learning) . Wrong! I got a pH of 4.7,

Hum if your boiling the water before you are using it then you are removing the temporary hardness. Perhaps this pdf will helps (it by the excellent John Palmer) but I don't see how you would drop the pH by more than about 0.1 pH units if you remove about 60 ppm Calcium - how hard is your water??? Does your keetle fur up with every boil???aunsure....
Does/did your grain bill have acidulated or really dark crystal malt in it?

Thinking hard now :tinhat:, did you actually precipitate out calcium phosphate salts and REALLY drop the pH???

 

[DrGMc]

Curious, why do you use an acid rest?

Ah well ...

During a contract I had in Brussels I worked with the owner of a brewery in Belgium and I picked his brains extensively on the subject of mashing (among other things). He was trained at the Catholic University by some famous trappists so he knows his stuff - don't get me started on multi step mashing.

Basically, the acid rest is great for us non-commercial brewers as we (usually) don't care about residency time (we are not looking at turnover and being as quick-as-possible unless SWMBO is about!). It is a process that breaks down the grain structure and releases extra phophate ions which is great for fermentation as its used by the yeast itself. Its simple to do as it only take a pause at 40 oC for about 10 minutes and hell, thats not a problem to temporarily hold the mix during its heating on the way to the "amylase" phase.

 

[DrGMc]

I'm with @Zephyr259, the most likely answer is that Bru'n Water is underestimating the pH drop due to crystal malts,

Spot on and I quote an important fact from Braukaiser ...

"Crystal type malts adhere fairly strongly to the "the darker the more acidic" rule. Roasted malts, on the other hand, show a fairly constant acidity regardless of their color. This is assumed to be the result of differences in the production process for crystal and roasted malts. The color of crystal malts is created while the malt is still wet which allows for the formation of more acidic compounds while the color of roasted malts is created after they have already been dried. Though that creates a stronger color it creates less acidity"

 

[cushyno]

When do people take the sample from the mash to obtain the Ph. I take mine after approx 10-15 mash time. My problem is that even though i get the Ph right in Bru'n water and i calibrate my meter(one of those yellow ones) using 6.8 & 4.1 solutions. the Ph i obtain once sample has cooled is often way lower than expected usually around the 3.5-4.5 mark. Any ideas where i am going wrong.

I took pH readings on my last brew day. Cooled a sample of the wort from the mash to 20°C. Used no crystal, but did use carapils. PH reading was bang on for my water but, mash pH read 3.7

That can't be right.

Mash prior to that showed pH as 5.8.

There was very little difference in water treatment for the two brewdays. I want to be more precise with water treatment, but with massive swings in pH that aren't reflected in beer quality, should I bother?

 

[Zephyr259]

I'm with @Zephyr259, the most likely answer is that Bru'n Water is underestimating the pH drop due to crystal malts, which is due to the fact that it's extremely difficult to accurately predict without knowing exactly all the parameters of the specific malts being used.

If this is happening consistently, then I would suggest simply aiming for a higher pH in Bru'n water to compensate, at least as a trial.

That's what I started doing, did the sums with a target pH of 5.5 - 5.55 while I tested the theory and it seemed to get me in the 5.3 - 5.4 range.

 

[Austin]

I live in a hard water area of the Thames Valley, I don't have any hi tech equipment but I can measure TA and pH with a simple colour strip. I have found that bringing mash water to a quick boil in a standard electric kettle makes the world of difference to the mash. The total alkalinity of cooled boiled water is reduced from 150ish ppm to nearly zero. Ph is returned to 7.
I recently mashed two identical AG sets of grain in virtually identical conditions with the exception that I didn't preboil the water in one, just heated it to mash temperature in a pan. The unboiled water mash extracted only 75% of the sugars compared to the pre boiled water, and it had other effects like reduced mouth feel. I concluded this is due to the mash reducing pH more optimally without any alkalinity to overcome.
In summary, start by pre boiling water to improve mash efficiency. I am up to about 75% brewhouse mash efficiency. I then use tap water to top up the fermenter and I believe this adds sufficient calcium for the yeast. One day I may add Epsom salts or Gypsum to correct water to match a beer style.

 

[strange-steve]

Ah well ...

During a contract I had in Brussels I worked with the owner of a brewery in Belgium and I picked his brains extensively on the subject of mashing (among other things). He was trained at the Catholic University by some famous trappists so he knows his stuff - don't get me started on multi step mashing.

Basically, the acid rest is great for us non-commercial brewers as we (usually) don't care about residency time (we are not looking at turnover and being as quick-as-possible unless SWMBO is about!). It is a process that breaks down the grain structure and releases extra phophate ions which is great for fermentation as its used by the yeast itself. Its simple to do as it only take a pause at 40 oC for about 10 minutes and hell, thats not a problem to temporarily hold the mix during its heating on the way to the "amylase" phase.

Interesting, I'm surprised there are commercial breweries still utilising an acid rest. I know it can be useful for promoting clove flavour in a hefeweizen and that it's used in some traditional turbid mash schedules in places like Cantillon, but for pH adjustment or yeast health it seems like an inefficient way of doing it.

 

[Argentum]

I have found that bringing mash water to a quick boil in a standard electric kettle makes the world of difference to the mash. The total alkalinity of cooled boiled water is reduced from 150ish ppm to nearly zero. Ph is returned to 7.

I don't believe it is possible to reduce alkalinity to below about 50-60 ppm via boiling and cooling your water. See the details for this about 2/3 to 3/4 of the way down this web page, at section 4.2.2 "Decarbonation Via Boiling".

https://sites.google.com/site/brunwater/water-knowledge

 

[DrGMc]

I live in a hard water area of the Thames Valley. I have found that bringing mash water to a quick boil in a standard electric kettle makes the world of difference to the mash. The total alkalinity of cooled boiled water is reduced from 150ish ppm to nearly zero. Ph is returned to 7.

One thing to remeber with this is that the boiling will remove all the CO2 and indeed reduce the alkalinity as you say - however, beware that sneaky CO2 ... if you leave the liquid open to the atmosphere it will literatly suck CO2 back in again so use it quick otherwise you will experience a pH swing that you should have but probably weren't expecting (unfortunately nothing in life is simple - apart from me )

 

[DrGMc]

Interesting, I'm surprised there are commercial breweries still utilising an acid rest. I know it can be useful for promoting clove flavour in a hefeweizen and that it's used in some traditional turbid mash schedules in places like Cantillon, but for pH adjustment or yeast health it seems like an inefficient way of doing it.

Steve, his comment was that they are small enough to be able to do things properly and they don't have to worry about residency times yet (i.e. they are not yet churning the stuff out 24/7 so not under pressure to release the vessels asap). I must admit I've just got into the habit of it now and not noticed any issues but now find consistenatly high efficiency across a range of grain bills after his advice on step mashing