[Kaiser]

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.

Kai

[bonjour]

RA are two letters that mean nothing to me off the top of my head,  Kai could you provide a description of that please.

Also each of your pH ranges seems to correlate with the Palmer lines.  I'd suggest a best fit line for each range to make the chart a bit more clear

Fred

[Kaiser]

RA measns residual alkalinity. Sorry I implied that.

Kai

[ndcube]

So the data is showing that for most beers you will need an RA of < 0 to achieve a pH of 5.2 regardless of color?

[majorvices]

So the data is showing that for most beers you will need an RA of < 0 to achieve a pH of 5.2 regardless of color?

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?    

[Kaiser]

So the data is showing that for most beers you will need an RA of < 0 to achieve a pH of 5.2 regardless of color?

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.

Kai

[a10t2]

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.

[ndcube]

Which beers needed an RA of -400 to achieve a pH of 5.4 at the very left of the graph?

[bluesman]

Quite a bit of scatter on the chart. The more basic the water... the harder the water is the conclusuion here. 

[Kaiser]

Which beers needed an RA of -400 to achieve a pH of 5.4 at the very left of the graph?

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

Quite a bit of scatter on the chart. The more basic the water... the harder the water is the conclusuion here. 

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.

Kai

[Kaiser]

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

[a10t2]

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.)

[ndcube]

...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.

[Kaiser]

I added trend lines to the chart.

Kai

[bluesman]

Looks like the cara malt has the biggest effect on the RA/SRM value.