Mash pH testing

[Jon474]

Does this little test have any scientific basis to it...

Boiled 1 litre of my Northumbrian Water tap water for 15 mins - vigorous boil (so much so that I lost 500ml)

Measured out 100g of MO pale ale malt.

Measured off 250ml of the boiled water - now at 72 degrees - into an insulated thermos coffee mug

Added the grist and brought temperature down to 66 degrees

Attached lid to cup and waited 10 minutes at which point the temperature was still at 66 degrees.

Took sample of wort at 10 mins and a second at 15 mins

First sample 5.9 - 6.1

Second sample 5.9

Can I take this scaled down test as a valid measure/indicator of my likely mash pH at the full brew lengths of 25-30 litres?

Obviously, this test shows my starting tap water produces a mash with an incorrect pH. I now need to do some tests on water treatment. I want to do them on this small scale but only if they scale up properly.

I did not add crystal malt to the grist as I like to add this to the copper but in any case would the addition of CM change the starting pH?

Your thoughts/opinions would be very welcome, please?

Kind regards
Jon

[Graham]

Does this little test have any scientific basis to it...
Can I take this scaled down test as a valid measure/indicator of my likely mash pH at the full brew lengths of 25-30 litres?

Yes it is valid, I have been doing something similar quite a lot just recently.

However, in your case it probably is not. You have probably got quite a lot of particulate chalk in suspension in your water, which will affect your mash pH. It needs to settle out. I would simmer (no need for a hard boil) for thirty minutes - and then give it time to settle, preferably overnight for the purposes of experiment. If your water is not very hard, the particle size may be too small to settle out. In that case, if you happen to have one of those domestic filter jugs, shove your boiled water through that (when cool), that will remove the suspended chalk.

Do you have any idea how hard your water is? Northumbria does not strike me as being a hard water area. It is harder to get the chalk to settle in water that is only moderately hard, although there are ways round it.

[Jon474]

Graham

Thanks for your reply. Feel very humble.

You make an interesting comment about small particle size - I saw no precipitation out of the water sample apart from a line of white around the pan as the water boiled away and a very few small, circular patches of white on the base of the very well cleaned and sterilised stainless steel saucepan. These patches of white easily washed away when I cleaned the pan after the test. My initial water sample was probably too small to make this a meaningful observation.

I am in Northumbria Water area T106 Nunthorpe which, as per their Aug 2008 report, suggests I have an average alkalinity of 87, calcium total of 33 (doesn't say of what though), degrees Clarke of 7 and "medium hardness" - which, I guess, accurately matches your "moderately hard" observation.

One question, do I need a vigorous boil for any period of time to drive off chlorine, fluoride etc which could taint the wort/finished beer? Will a short boil then a 30 minute simmer remove such chemicals?

Regardless of any reply to this question, I will repeat the test using the method you suggest - I will boil/simmer a larger water sample now (watching Sky-plused DotT part Two) for 30 mins. I don't have access to a filtration system - and wonder even if I did, whether or not I want to filter? Could such a filtration be repeated on the scaled up process? Don't know. For now, I will attempt to carefully rack off the boiled, cooled water and re-micro-mash in the morning. I'll record all volumes, weights etc and post the results.

The idea of these micro-tests just struck me as a convenient way of reproducing on a small-scale the likely outcome of the mash pH % by weight of the grist for a variety of beer styles to see what water treatment might be necessary. Obviously, it only works if it can be accurately scaled up.

Many thanks again for your reply.

Kind regards
Jonathan

[Graham]

I am in Northumbria Water area T106 Nunthorpe which, as per their Aug 2008 report, suggests I have an average alkalinity of 87, calcium total of 33 (doesn't say of what though), degrees Clarke of 7 and "medium hardness" - which, I guess, accurately matches your "moderately hard" observation.

Your water is probably liveable with without boiling, although you will need to get your calcium levels up if you want clear beer. Your alkalinity turns out to be about 52ppm as carbonate, which is a bit on the high side, but can be compensated for with additional calcium.

One question, do I need a vigorous boil for any period of time to drive off chlorine, fluoride etc which could taint the wort/finished beer? Will a short boil then a 30 minute simmer remove such chemicals?

The chlorine will be gone long before the water reaches the boil. Another chemical, chloramine is rare in British water, unless you really live out in the sticks, but that will be gone after a thirty minute boil too. I think the effect on beer of residual chlorine in water is overhyped, but if you have any concerns the campden tablet trick often mentioned on here will deal with it. Fluoride doesn't matter, but it will give your yeast healthy teeth, so watch where you put your fingers.

I don't have access to a filtration system - and wonder even if I did, whether or not I want to filter? Could such a filtration be repeated on the scaled up process? Don't know. For now, I will attempt to carefully rack off the boiled, cooled water and re-micro-mash in the morning. I'll record all volumes, weights etc and post the results.

Lining a flour sieve with those green, 3M-type, scourer things, and running the water through them seems to be good at removing suspended chalk. I don't have enough concrete data to positively recommend it, but it seems to work.

The problem with water of low hardness is that the chalk particles do not grow to sufficient size to be heavy enough to drop out of suspension. They come out of solution after the boil but remain in suspension. Your water, I fear, is in that category. One way of overcoming this is to add a teaspoonful precipitated chalk to the water during the boil. It may seem daft adding chalk to water to get the chalk out of it, but it gives the opportunity for the suspended particles to become larger and heavier. Home brew shops sell precipitated chalk. Filtering also takes out the chalk in suspension (but not chalk in solution). As I said, you probably do not need to boil. You will have to get some gypsum to raise your calcium levels though.

If, during your tests, the pH is too high, stir some gypsum into it and see if it comes down. If it does, you will be okay. Worthwhile trying it with untreated water as well.

[Jon474]

Okay...not sure of the scientific validity of the last twenty four hours but it has been interesting.

I am trying to develop a process to show me what my likely mash pH will be for certain compositions of grist. I don't want to do this at full brew lengths as this would just be too wasteful on resources. So,I am doing this by reproducing the brewing liquor treatment and the subsequent mash, on a micro-scale - between 1-6 litres of brewing liquor, 250ml of mash tun water/100g of grain. The process has been the same for each test: treat water, allow to cool overnight (if test requires it), heat water to 80C, strike at 72C, adjust mash temperature to 66C, cover and insulate mash tun, wait ten minutes and then measure pH. The HLT was a well-cleaned stainless steel saucepan, the mash tun was a Thermos insulated coffee mug.

Five tests:

1 Tap water (2 litres), no treatment, heat straightaway to 80C then follow procedure as above

2 Tap water (1 litre), boil vigorously for 15 mins, cool to 80C then follow procedure as above

3 Tap water (2 litres), simmer for 30 mins, cool to ambient overnight, heat to 80C then follow procedure as above

4 Tap water (5 litres), add 3g of gypsum, simmer for 30 mins, cool to 50C, add 1g epsom salts, 1g common salt, 1g citric acid, cool to ambient overnight, heat to 80C then follow procedure as above

5 Tap water (6 litres), add 7g of gypsum, simmer for 30 mins, cool to 50C, add 1g epsom salts, 1g common salt, 1g citric acid, cool to ambient overnight, heat to 80C then follow procedure as above

The confusingly different volumes used were because my scales can only go down to 1g and I needed to get to whole units of additives. The gypsum, epsom, salt and citric acid suggestions are from GW's "Home Brewing", 1993.

Observations on the water after treatment:

1 No change in water appearance, some white marks around edge of pan, no precipitate could be seen, nothing on base of pan observed or felt when cleaning

2 No change in water appearance, some white marks around edge of pan, no precipitate could be seen, nothing on base of pan observed or felt when cleaning

3 Slight, faintly visible,appearance of scum on surface of cooled water which rapidly disappeared when water was disturbed, some white marks around edge of pan, no precipitate could be seen but could feel a slight dusting of very fine grit on base of pan when cleaning it afterwards

4 No change to water's appearance, no precipitate could be seen, nothing on base of pan observed or felt when cleaning

5 No change to water's appearance, no precipitate could be seen, nothing on base of pan observed or felt when cleaning

Results:
1 pH 5.9
2 pH 5.9
3 pH 5.9
4 pH 5.5
5 pH 5.5

Graham's points about low particle size and chalk remaining in suspension seem to be confirmed. Test 3 seemed to get the most chalk out in mechanical terms but tests 4 and 5 achieved the most chemical effect.

So, adding gysum has reduced the pH (phew, the chemistry works) but, even with the doubling of the amount of gypsum in test 5, the pH has not moved from a level of pH5.5. Presumably I am seeing the effects of buffering here? I could presumably carry on adding larger and larger amounts of gysum, at will, but still only achive a slight change in pH? More citric acid might effect an additional lowering of the pH. I am tempted to say that following test 5 and producing a pH5.5 at scaled-up brew lengths is enough for now and see how the brews come out.

Where am I going with this? Not sure. It has been an interesting diversion into the realm of water treatment though. I need to look at feeding in an accurate analysis of the T106 water into Graham's water treatment engine. I did a preliminary assessment (albeit a very unskilled assessment using alkalinity of 87 and hardness of 33 CaCO3) using the treatment engine which suggested to add quite a lot of gysum, a little bit of calcium carbonate and no epsom or common salts. Hey, that seems to pretty much match the empirical evidence I have obtained from my five tests.

It is a great hobby this one.

Happy New Year to all.

[Graham]

It is a good test - I wish more people did stuff like that. It nice to see what works for some people and what does not.

Did I really say citric acid in Home Brewing? I hope you found that in someone else's book. Citric acid alone will lower the pH and will screw your results. I will have a look later, but I think I kept it really simple in that book and suggested gypsum, Epsom salts and, optionally, ordinary salt. I don't think that I even mentioned calcium chloride, because I did not want to make it seem too complicated, and I don't usually bother with calcium chloride myself anyway.

I am surprised that your pH is not lower, even if you did not used citric acid, but it is fair enough. For pH tests you only need to bother yourself with gypsum and / or calcium chloride because these things are the only ones that affect mash pH.