Well, after a long hiatus a new -- and totally-redesigned-under-the-hood -- version of my brewing water calculator is now released: MpH 4.2.
The equations used to calculate mash pH have been completely reworked. The new equations are directly based on A.J. deLange's ideas regarding charge conservation when mixing different malts or adding acids to the mash. The new calculator also leans heavily on experiments that Mick Spencer and I did on the grist pH and buffering capacity of a large number of malts (details of which can be found in the paper discussed in the previous post to this blog). I must also give a shout out to all those homebrewers (on either the Beer Advocate Homebrewing Forum or HomeBrewTalk) who provided data so that I could nail down the last parameter that was required to make the whole thing go.
Has it really been nearly four years since I posted the last version? I guess so.
Cheers!
Thank you once again for releasing MpH 4.2. I've been looking forward to this latest release since you first mentioned it was in the works. I'm downloading it now and will update you soon!
ReplyDeleteHi, thanks for posting this spreadsheet. The mash pH changes when you add strike water salts, but on the sparge water and sparge acid tabs, if you add salts it doesn't change the amount of acid needed to obtain a certain pH. Is this correct? I thought that adding some "decreases pH" salts would lessen the amount of acid you need in the sparge water.
ReplyDeleteSalts added to the strike water affect mash pH owing to their interaction with the malt. This interaction, along with the alkalinity of the strike water, produces what is known as residual alkalinity, which is one key to determining the mash pH. Salts added to water do not change the pH because there is no malt in the sparge water. I hope this makes sense.
ReplyDeleteThanks for the explanation. It does make sense.
DeleteHi, you have set the Malt Buffering Correction Factor to 0.6 and I was wondering how you determined this value.
ReplyDeleteThat value was determined by comparing the MpH calculations to a collection of mash pH measurements made on a variety of beers by a number of homebrewers. The value 0.6 gives the best overall agreement with the data I had at the time. I am continuing to evaluate data, as I have recently received more measurements. The jury is still out, but it may be that 0.65 turns out to be a slightly better number. However, such a difference would not be all that significant. Cheers!
DeleteHi
ReplyDeleteMany thanks for the information. I am currently comparing all our brews going back a year to see what the correction factor would need to be to hit the actual mash pH. I have fed all your buffering capacity data into my own spreadsheet to supplement our own experimental data for mash pH in distilled water as the bulk of our grains are from the UK. I have therefore had to estimate some values of B based on your values for similar malts.
We are going to carry out some of our experiments based on the process outlined in your paper to determine the best fit for pH1, pH2 and r. The only problem is getting hold of Briess Caramal 120L and L10 in the UK. We may use Simpson's DRC Briess Aromatic if all else fails. It will be interesting to see what values we get for Flaked Rice, Simpson's Golden Naked Oats plus a few others.
Many thanks for all your work and in particular the three research papers that you published covering mash pH modelling. My spreadsheet now incorporates 5 models (MpH but using the SRA slope rather than Z alk, EZ Water, Brun'Water, Kaiser Water, and an earlier model published by KT). From this we can compute upper and lower bounds for the mash pH which is really helpful in fine tuning the water profile and salt additions.
I will let you know what I get for the correction factor range based on my data. For your info we use a Braumeister 50L, RO water and Residual Alkalinity is determined using equation (7) in your Mash pH II paper.
Keep up the good work.
Cheers
Colin
Hi
ReplyDeleteUsing the measured mash pH from the last 25 brews I have determined that the modified equation for predicting our mash pH is:
pH(estimated) = 0.986 pH(DI) + 0.677 pH(salts) + 1.94 pH(acid)
based on a least squares analysis.
This equation has been determined omitting the 0.6 correction factor and using the SRA slope (R/Bi.fi). I am going to apply the equation to the 52 brews we did in 2019-20 to see how close it correlates to the actual pH.
It is interesting to note that pH(DI) is very close to your eqn (4) in paper III. However, I am surprised at how the pH shift for the acid is nearly doubled almost mirroring the factor applied in the EZ Water model. Checking a number of the brews from 2019 the equation predicts the mash pH with an accuracy of less than +/- 0.08 and less for the majority of brews.
Once I have worked through the data from 2019 I will let you know the outcome.
Cheers
Colin
Hi Colin,
DeleteCould you please explain your equation for pH above? I don't understand the second and third terms, and I'm not sure I understand the first term.
Would you be interested is sharing your brewing data? From my point of view, It would be helpful for fine tuning the correction factor.
DMR
Hi Mark
DeleteI have dropped you a post.
Cheers
Colin
Post, as in mail? Or an email? Or are you referring to the comments below? Sorry for my confusion. If an email, I've not received one from you, I don't think. Cheers!
DeleteHi Mark
ReplyDeleteThe equation is formulated as follows:
1. The first term is the pH of the grist mashed in distilled water and given by equation (4) - your paper part III.
2. The slope SRA is determined by dividing the mash thickness R by the sum of Bi.fi as per your spreadsheet
3. The second term is the pH shift due to the salt additions where the residual alkalinity (Ares) is determined using equation (7) from paper II.
4. The third term is the pH shift due to the addition of lactic acid where the residual alkalinity change Aac is determined using equations (13) in paper II.
5. The predicted mash pH is therefore the sum of the pH of the grist in distilled water plus the pH shift due to the salt additions plus the ph shift due to the lactic acid. The slope SRA is assumed to be the same for the second and third terms.
Normally the residual alkalinity used in equation (3) of paper II is the final value taking account of the slats and acid additions. I have just separated them.
6. I have assumed that the pH of the mash is given by:
pH (mash) = a.pH(DI) + b.pH shift (Salts) + c.pH shift (Acid)
I initially set a = b = c = 1 which is the predicted pH from my spreadsheet where the first term uses the buffering capacity for each malt, the second and third terms use approach you outlined in paper II.
For the 25 brews I worked out the predicted pH using the new model and compared it to the measured pH. Using a least squares analysis I derived the coefficients a,b and c.
It is interesting to note that the inverse of the coefficient c is 1/1.94 = 0.52 which is close to your correction factor of 0.6. However, the correction factor for the salt additions is 1/0.677 = 1.48. Therefore the correction factor is not the same for both the salt additions and the lactic acid.
Having said that, the majoity of the 25 brews have lactic acid additions of varying degrees ranging from 1ml to 6ml in 55L.
What I am going to do next is check the model against other brews particularly those with low or zero lactic acid.
I am quite happy to share data with you and have over 100 brews with mash pH measurements and accurate water profiles. We brew every week for the pubs so ongoing data is no problems.
Hope my explanation is OK.
Cheers
Colin
Hi Mark
ReplyDeleteHere is an example of a mash pH prediction for one of our brews:
1. Source water reverse osmosis
2. Water profile after salt additions
Ca = 110; Mg = 10; Na = 40; SO4 = 210; Cl = 83; Alkalinity = 67
2. Malt
Maris Otter (Bairds) - 9.76kg; pH(DI) = 5.7; B = 49.5
Crystal (EBC = 100) = 0.68kg; pH(DI) = 4.4; B= 65
Simpson's DRC = 0.56kg; pH(DI) = 4.34; B= 74
Victory Malt = 0.46kg; pH(DI) = 5.19; B = 36.8
Mash thickness = 55/11.46 = 4.80
The Buffering values are taken from your paper. The pH(DI) values are our own based on 20g of malt and 100ml of DI water giving a mash thickness of 5.
3. Measured mash pH at 20C = 5.38
4. Model
Residual Alkalinity = -38.7
pH (grist) = 5.491
pH (salts) = -0.073
pH (acid) = 0
pH (predicted) = (0.986*5.491 + 0.677*-0.073) = 5.365
Error = 5.38 - 5.365 = 0.012
Cheers
Colin
Hi Colin,
DeleteThanks for the explanations. When I get the time, I'll take a careful look at them. Thanks, again!
dmr
following ...
ReplyDeleteHi. How does one represent acidulated malt additions in the sheet?
ReplyDeleteGot it, nvm :)
DeleteQuick question on 4.2. Are calcium chloride calculations in the spreadsheet based on dihydrate or anhydrous?
ReplyDelete