Need help interpreting test mash numbers

[joshesmusica]

Ok I did two test mashes this evening. In each one, I had 200g pilsner malt, 2L tap water, and added .5ml of 80% lactic acid - I tried to hold the temp consistent at 64C. This was typed into the Bru'n water spreadsheet, along with the averages from my city's water, and it said I should be expecting a pH measurement of 5.33. I tested each mash in 15 min intervals. I had to run the malt through a blender because the LHBS wouldn't run such a small amount through their mill. I think the first round didn't get crushed quite good enough, but in the end, there were some similarities in the measurements.

1st test mash results:
15 - 4.85
30 - 4.98
45 - 5.01
60 - 5.07

2nd test mash results:
15 - 4.96
30 - 5.11
45 - 5.18
60 - 5.18

Interesting to me that they both rose .22 from the 15 minute measurement to the 60.

What does this mean for the buffering capacity of my water in this situation? No matter how I adjust the minerals in the spreadsheet, I can't replicate anywhere near these numbers. Is this too small of an amount for this particular spreadsheet?

Brewer's friend was actually not too far off, predicting 5.01.

 

[mabrungard]

The result suggests that your tap water alkalinity is not as high as the average report result indicates. Are you sure that your lactic acid is 80%? We typically have 88% lactic acid available at our homebrew shops.

The mash pH rising during the mash rest is typical. My experience is that mashing pH tends to drift toward 5.4 when the initial mash pH is either higher or lower than 5.4. In your case, the rise from the low 5 range is typical. I don't know why 5.4 seems to be dividing point. I can only assume that there is some sort of buffering activity in the mashing materials that produces this result.

 

[joshesmusica]

The result suggests that your tap water alkalinity is not as high as the average report result indicates. Are you sure that your lactic acid is 80%? We typically have 88% lactic acid available at our homebrew shops.

The mash pH rising during the mash rest is typical. My experience is that mashing pH tends to drift toward 5.4 when the initial mash pH is either higher or lower than 5.4. In your case, the rise from the low 5 range is typical. I don't know why 5.4 seems to be dividing point. I can only assume that there is some sort of buffering activity in the mashing materials that produces this result.

Yeah, had to check twice that it was 80%, since I was under the impression that it's common to have 88%. Don't know why they have it as 80%. This is what I have:

https://www.brouwland.com/en/our-pr...ic-acid-80-vinoferm-lactol-100ml#.V92us7US3hM

So when is the time that these calculators should be accurate? 5 minutes in, 15 minutes in, at the end of the mash after it adjusts?

The bru'n water spreadsheet (the donation version) was off by a significant margin. I adjusted the input to 0.1 for pretty much every section. The lowest I could get it to predict was 5.29. Can the algorithms in place just not handle such low volumes?

I'd much prefer using the spreadsheet than an online calculator with every batch.

 

[ajdelange]

The algorithms should be independent of volume. It is the models that are imperfect. And there is no way in which the model in any particular program can know the parameters of the malts you are using. The most robust models require entry of data concerning the acid/base properties of each malt and what I call its 'temperature glide' which is how much the pH changes per °C change in temperature. As it is impractical for the home (or other small scale) brewer to measure these each time he buys a pound of some specialty malt the popular programs/spreadsheets rely on some broader empirical means to estimate malt properties such as their type or color or both. Clearly such techniques aren't going to give a precise answer but neither is the more robust approach because of the lack of data. If I attempt to predict your pH knowing that you used pilsner malt then I must ask "Is his pilsner malt like Weyermann's normal polsner malt with its DI water pH of 5.62 and its buffering of -40.7 or their floor malt with its DI pH of 5.85 and buffering of -31.3 or Rahr Pils with pHdi = 5.80 and buffering -46.3? Or is it more like some other pilsner malt that I have never measured. Then there are seasonal, varietal and lot variations to contemplate. The test mash is a much more practical approach for the small scale brewer than pH estimation if accurate answers are desired but that doesn't mean that the less accurate answers from a calculator, even the less robust ones, aren't of value because they give you an idea as to where you will land to ± 0.1 or so pH and that is valuable in helping you to set up a test mash.

The fact that your test mash was so far off from the spreadsheets' predictions here is not so disturbing as the fact that you did 2 identical test mashes and got answers that differed bu 0.1 pH. This calls into question your measurement technique. They should have been very close. This makes it hard to attach credibility to either of them.

As to what this says about the buffering capacity of your water it says that it is very low. Slightly less than 0, in fact, for the sets of reasonable pilsner malt parameters I played with so that again casts suspicion on the pH readings. What is the alkalinity of the available water?

As to the 'when' question. That is a very good question. The reactions that take place in the mash tun are fairly slow and seeing a rise in pH over time is perfectly normal over time if you have added acid as the acid goes into solution very quickly and the pH electrode picks up its presence right away. As the grain gets fully wetted and the acid makes its way into the interior of the grist and is neutralized by it the pH rises. Conversely if you have added a base to the mash the pH will be higher than target and will, as the alkali makes it into the grist and is neutralized by it, decrease towards target. If the water contains a lot of calcium this will react with malt phosphate and release acid so that you will have a decrease in pH over time as that reaction proceeds which may offset or augment the drift caused by added acids and bases.

So when do we take the pH measurement? We've sort of standardized at 20 minutes to half an hour. It is unusual to see pH drift as much after half and hour as you saw.

 

[joshesmusica]

The fact that your test mash was so far off from the spreadsheets' predictions here is not so disturbing as the fact that you did 2 identical test mashes and got answers that differed bu 0.1 pH. This calls into question your measurement technique. They should have been very close. This makes it hard to attach credibility to either of them.

As to what this says about the buffering capacity of your water it says that it is very low. Slightly less than 0, in fact, for the sets of reasonable pilsner malt parameters I played with so that again casts suspicion on the pH readings. What is the alkalinity of the available water?

As to the 'when' question. That is a very good question. The reactions that take place in the mash tun are fairly slow and seeing a rise in pH over time is perfectly normal over time if you have added acid as the acid goes into solution very quickly and the pH electrode picks up its presence right away. As the grain gets fully wetted and the acid makes its way into the interior of the grist and is neutralized by it the pH rises. Conversely if you have added a base to the mash the pH will be higher than target and will, as the alkali makes it into the grist and is neutralized by it, decrease towards target. If the water contains a lot of calcium this will react with malt phosphate and release acid so that you will have a decrease in pH over time as that reaction proceeds which may offset or augment the drift caused by added acids and bases.

So when do we take the pH measurement? We've sort of standardized at 20 minutes to half an hour. It is unusual to see pH drift as much after half and hour as you saw.

Yeah, unfortunately I guess, the mashes were not completely identical. I thought the first mash was crushed well enough, and didn't really know if it would be a good idea to basically grind it all to powder. So I don't think all of the malt's "buffering capacity" became available. At least that was my theory as to why it continued to rise to the end, and the second one didn't rise in the last 15 minutes.

I guess I'll have to buy a full kilo of grains so that way the LHBS won't act so troubled by having to crush it. Then I will know everything about the mashes will be completely consistent.

Should I just go with something bigger this time? Now that I have a pH meter I was wanting to try a sour mash. So I guess this would be a good opportunity to do that.

Still don't know what to do about the two calculators giving different outputs, especially considering that the northern brewer one was actually really close, even more so if we're talking about the measurements at the 30 min mark.

Here's what I've put into both of the calculators:

Bestmälz pilsen malt - 1.8 lovibond.

Ca - 3.2
Mg - .3
Na - 1.2
Cl - 1.1
SO4 - 1.6
Alkalinity as ppm CaCO3 - 12.3 (in BW it said this was equivalent to 15ppm bicarbonate)
pH - 6.7

Northern Brewer - 5.01pH
Bru'n Water - 5.33pH

 

[ajdelange]

Should I just go with something bigger this time?

That shouldn't make any difference unless it is easier for you to get an accurate measure of a larger quantity.

Still don't know what to do about the two calculators giving different outputs, especially considering that the northern brewer one was actually really close, even more so if we're talking about the measurements at the 30 min mark.

There really isn't much you can do about it. It is the nature of the beast. Now that I have some data on you water I can estimate mash pH. This uses a robust mash pH estimation algorithm but I still have to guess at your malt properties. The following values are for malts measured by me or a correspondent

Weyermann Regular Pils 5.12
Weyerman Floor Pils 5.13
Rahr Pils 5.27
Rahr Pale Ale 5.21

About the best I think you can do is to use several of the calculators each time you brew and compare their predictions with what you observe. The hope is that one of them will be a better predictor for the particular beers you brew than the others.

There is one major caveat and that is confirmation bias. Many brewers report that their particular spreadsheet choice is spot on. They do this by measuring pH and as soon as it drifts to the predicted value declare victory and chalk up another for SudsoBrew. You must be very careful to not fall into this trap. It is very easy to.

Here's what I've put into both of the calculators:

Bestmälz pilsen malt - 1.8 lovibond.

Ca - 3.2
Mg - .3
Na - 1.2
Cl - 1.1
SO4 - 1.6
Alkalinity as ppm CaCO3 - 12.3 (in BW it said this was equivalent to 15ppm bicarbonate)
pH - 6.7

Northern Brewer - 5.01pH
Bru'n Water - 5.33pH[/QUOTE]

 

[joshesmusica]

That shouldn't make any difference unless it is easier for you to get an accurate measure of a larger quantity.

There really isn't much you can do about it. It is the nature of the beast. Now that I have some data on you water I can estimate mash pH. This uses a robust mash pH estimation algorithm but I still have to guess at your malt properties. The following values are for malts measured by me or a correspondent

Weyermann Regular Pils 5.12
Weyerman Floor Pils 5.13
Rahr Pils 5.27
Rahr Pale Ale 5.21

About the best I think you can do is to use several of the calculators each time you brew and compare their predictions with what you observe. The hope is that one of them will be a better predictor for the particular beers you brew than the others.

There is one major caveat and that is confirmation bias. Many brewers report that their particular spreadsheet choice is spot on. They do this by measuring pH and as soon as it drifts to the predicted value declare victory and chalk up another for SudsoBrew. You must be very careful to not fall into this trap. It is very easy to.

Here's what I've put into both of the calculators:

Bestmälz pilsen malt - 1.8 lovibond.

Ca - 3.2
Mg - .3
Na - 1.2
Cl - 1.1
SO4 - 1.6
Alkalinity as ppm CaCO3 - 12.3 (in BW it said this was equivalent to 15ppm bicarbonate)
pH - 6.7

Northern Brewer - 5.01pH
Bru'n Water - 5.33pH

[/QUOTE]

Did a couple of new test mashes today. Something I'm turning into a first attempt at a sour mash as well. They were both 6L of water - 2kg of Crisp Maris Otter - 1.5ml 80% lactic acid. Targeted mash temp was 66C.

Bru'n Water predicted 5.3, Brewer's Friend predicted 5.29. So this time they were, obviously, much closer to each other.

Final results from the mashes:

1) 15 min - 5.21, 30 min - 5.26, 45 min - 5.3, 60 min - 5.3

2) 15 min - 5.20, 30 min - 5.31, 45 min - 5.33, 60 min - 5.34

The differences between the two were much smaller this time. I'm wondering if it's just because of the not 100% precise measuring of the acid (it's a 10ml little syringe that is marked in .5ml increments), the fact that I didn't have the best pot for the job, so maintaining the temperature was likely slightly different for each mash, or that maybe one batch had a higher powder-husk ratio. I don't know. Should I be more satisfied with the results this time?