Tonight I finally finished something quite interesting that I was working on for the last few days. I’m trying to come up with RA guidelines based on the beer SRM. Similar to what John Palmer is already doing but based on my research with respect to malt acidity and water chemistry.
I ended up writing a script that can create random recipes based on a few guidelines. There are different types of recipe templates as well. Those templates are for example “all base malts” “base malts and up to 15% cystal malts”, “base malts and up to 15% roasted malts” … and a few more that I don’t feel like listing. For these recipes I can use the pH estimator that I’m working on and which seems to work for my few recent beers. That allows me to determine the SRM of the beer and the necessary residual alkalinty to reach a pH of 5.2, 5.4 and 5.6. For the ~140 “recipes” I plotted that RA over the beer SRM and also included John Palmer’s min and max RA guideline and this is what I came up with:
I expected some spread, but not that much. No wonder than breweries like Stone can use their 100 ppm CaCO3 hardness water for such a wide range of styles. And there are also a number of outliers. Beers that would need a ridiculously high or low RA to create an acceptable mash pH.
I have yet to do more qualification on that data and possibly limit the recipe templates some more to create even more realistic recipes. Stay tuned for that. Right now I just felt like sharing that chart.
I have read his post three or four time and I have been wondering what the actual conclusion was. Damn, I am no scientist, that is for sure. The only conclusion I came to was that there is a wider water mineral profile applicable to individual styles than is often thought (?)
Kai, can you dumb it down for the rest of us “non-German engineering types” please? :-\ ;)
Yes, that’s what surprised me too. My explanation is that 5.2 is already the low end of the optimal pH range. 5.4 -5.6 is a better target and this is where John’s approximation catches the bulk of the beers. In addition to that, at a mash thickness of 3 l/kg (~1.5 qt/lb) it takes a residual alkalinity change of 100 ppm as CaCO3 to cause a pH change of only 0.1, hence the large spread and the wide variety of beers that can be brewed with a given water.
There are so many ways to cut and display this data. I have yet to find the best one. Fred’s suggestion with plotting a good fit is a good one. I’ll have to give that a try.
Interesting stuff, thank you Kai. It does match up with my experience. I have very hard water and don’t always buy quite enough distilled to hit the high end of Palmer’s SRM range, but my mash pH always ends up in range.
I guess that they ended up having lots of 6-row and/or wheat in them. Both these malts tested with a distilled water pH of close to 6 which then takes much more acidity from the water to bring them to 5.4. In fact to get from 6 to 5.4 the pH needs to be lowered by 0.6 which amounts to an alkalinity of -600 ppm as CaCO3. But these are the extremes and I’m not sure if my pH prediction formula still works there. I do, however, remember that I needed quite a bit of acid malt in my CAP to get the pH to 5.5. More than I anticipated based on my experience with Pilsner malt mashes
I’m not quite sure what you want to say. If you use “basic” to refer to the water’s alkalinity then you are correct. More alkaline waters need to be harder then less alkaline waters. But a hard water doesn’t necessarily have to be very alkaline. You can have lots of permanent hardness (much more Cl and So4 than bicarbonates) which results in a hard water with low or even negative residual alkalinity.
Here is another interesting display of the data. I reran the script after removing 6row and wheat from the list of available base malts.
“base malt” means that only a mix of base malts was used in the grist. The percentages and amounts of base malts are random. Each grist can use up to 3 different base malts and base malts include Pils, 2-row, munich I & II, Vienna and Maris Otter Pale.
“cara” means that up to 15% of the grist is a mix of up to 3 different cara malts. The rest is a mix of base malts though strongly biased towards using only 2-row.
“roasted” is the same as cara with the difference that only roasted specialty malts could be used. Those include roast barley, black patent and 2 carafas.
“cara and roasted” are like “cara” with the difference that up to 8% cara malts and upt to 8% roasted malts were allowed.
Kai, that’s an even more useful view IMHO. Any chance of getting the equation for some sort of curvefit through the middle of that data? (It looks like a linear fit would be fine for our purposes, and I guess I could just eyeball it.)
…and (you may have mentioned your doing this already) make a calculator that incorporates the malt split for the grain bill as well as SRM to get our needed RA.
this is what I expected since the have more acidity per unit of color when compared to roasted malts. And since you need roasted malts to get to the really high SRM values your RA over SRM curve flattens out significantly for really dark beers and there is no need to go above an RA of 200 ppm as CaCO3 for those.
Wow…I can only partially grasp all this on first read, but I look forward to getting into it more deeply. And Kai, I want to say thanks for all the absolutely great work you’re doing!
I’ve said it before, but it needs repeating… Kai, your desire and willingness to experiment and document your findings is an invaluable service to homebrewers!!
I almost feel like I understand mash and water chemistry. Then I re-read your articles and realize how much I missed the first time around.
If you can make a script to model all this, can you make a spreadsheet or program which allows you to select the % of each type of malt (base, cara, roasted) that will spit out RA and SRM ranges?
Thanks. Now that I started going down that road I want to finish the work and feel I should also try to find practical advice and guidelines. And hopefully a model that also explains brewer’s experiences that have not be explained so far. W/o that it would have be waste of time.
Personally, I like playing around with grist and water compositions in a spread sheet that I’m working on which takes into account the malt characteristics that I measured. But I cannot expect that from other brewers. While a bit flawed Parmer’s approach to suggest RA targets based on beer SRM is a very practical one since most of us already calculate and target beer SRM through the use of brewing software/spreadsheets. I stopped calculating beer SRM a long time ago because I was never really interested in the actual value. If, based on previous batches, I compose the grist correctly the beer will have the desired color. Introducing a new metric like mash color, for example, to predict the needed RA would only make the process more complicated.
Only if this mash pH model can be integrated into popular software like Beersmith would I have a shot at reaching a wide audience with a more precise RA estimation. I doubt that there is actually a need for that level of precision. On the other hand, homebrewers like to tinker with things that commercial brewers don’t even worry about, so we will see.