Version 2.0 of Palmer's Residual Alkalinity Spreadsheets

[ajdelange]

Adding phosphoric acid to the mash would be preferable to adding it directly to the water before mashing?

I don't think it matters. To get to a particular mash pH you must 1. Move the water to that pH and 2. Move the grist to that pH. The total amount of H+ required to do that should be the sum of the H+ required by both 1 and 2.

In the case of sparge water acidification, it appears that phosphoric acid may not be an ideal choice if the brewer expects to carry over the same calcium concentration into the wort. That effect would still be minor if I understand your analysis result.

If the water is devoid of calcium the reaction would be (for alkalinity of 100 and acidification to pH 5):

.945H3PO4 + HCO3- --> 0.96CO2 + .04HCO3- + 0.992H2PO4- +0.006HPO4--
(coefficients are millimoles)

Thus (per liter) it takes about 1 mmol of the acid to convert enough bicarb to CO2 to get the pH to 5 but about a mmol of the monobasic phosphate ion remains. This will strip remaining calcium from the mash/wort.

OTOH if the water is also hard to the extent of 100 ppm as CaCO3 we should get something like:

.5Ca++ + HCO3- + (0.3+.01)H3PO4 + 0.1H2O --> .05*Ca10(PO4)6(OH)2 + 0.96CO2 + .04HCO3- +.01H2PO4-

Considerably less phosphate is required here (0.3 to precipitate the calcium and get rid of the alkalinity and the rest to acidfy this now 0 alkalinity water to pH 5) and much less monobasic phosphate ion gets carried over.

So it appears that you must pay the piper one way or the other. In fact, the actuality will lie somewhere between the two extremes because in the case of the example the system will go below saturation well before pH 5 is reached and the mechanism for proton release switches to the first of the two at that point.

The quantity of phosphate in the mash is larger than the quantity of calcium supplied by the water, but I take it that the precipitation reaction cannot go to completion in the mash because the phosphate in the malt is not in an acidic form. Would that be the case?

At mash pH most of the phosphate will be in the monobasic form so the reaction is

10Ca++ + 6H2PO4- + 2H2O --> Ca10(PO4)5(OH)2 + 14H+

as opposed to

10C1++ + 6H3PO4 + 2H2O --> Ca10(PO4)5(OH)2 + 20H+

for the acid. IOW H2PO4- is an acid (it has 2 protons to give) while it is simultaneously a base (it's amphoteric) because it can take up a proton.

The calcium phosphate precipitation is not a huge factor in the overall carryover of calcium into the wort. Looking at Tables 7.5 and 7.6 of Malting and Brewing Science confirms that although there may be a reduction in the calcium concentration, it appears to be minor. Is that in line with your findings?

I don't think we can draw too many conclusions from the table is BHS&Y. If no phosphoric were used in pH adjustment of water or mash then there would be no reduction in calcium levels. This would also be the case if mash pH reduction were effected by the use of other acids. You'll note that both chloride and sulfate levels are higher in the wort and beer than they are in the liquor and this suggests that for ale being described a mixture of sufuric and hydrochloric acids may have been employed. This is consistent with my understanding of commercial brewing practice in the UK. CRS (Carbonate Reducing Solution) is a blend of sufuric and hydrochloric acids. In addition to this remember that malt itself contains about 0.14% Ca w/w.

[Colin Kaminski]

I can confirm most London and Burton breweries use Sulfuric with a little HCl. In the north there is more use of HCl. Using HCl give the beers a rounder taste and H2SO4 gives the beers a crisper taste. The is because HCl leaves Cl ions in the finished beer and H2SO4 leaves SO4 ions in the finished beer. Blending them strikes a balance. We can also do this with CaSO4 and CaCl. I almost always use a blend of acids. H2SO4 first then Phosphoric is a nice acid for the lower hop quick selling beers.

[Colin Kaminski]

PS AJ, I have no idea what so ever why I would care what the pH of my strike water is as long as I hit my mash pH. I make my water have a specific RA for the recipie and then move on. Am I missing something? I can think of waters that have an RA of 0 ppm that are a pH of 8 and a pH of 6.8, I don't really think my recipie would taste any different as long as the SO4/Cl ratios were the same.

[ajdelange]

No, I don't think you are missing anything. The reason I based some of my comments on moving the water to a particular pH was because you had said that when you add acid to water it usually comes to pH 7.2. As I said in another post, you are going to have to pay the piper one way or another i.e. you need enough acid to overcome the alkalinity of the water and the "alkalinity" of the malt.

[Deathrider]

First off, you guys are awesome!! I have been working in a hospital lab for 30 years and the last time I had to do these equations was in college
What I would like to see (and probably everybody else) is a summary of your findings. Especially as it applies to a 6 gallon batch and what water should be achieved for a particular style or group of styles of beer. I realize that we all have different water to start with, but if you could summarize a final water chemistry we should strive for.
I also realize that most homebrewers should not be playing around with hydrochloric acid or sulfuric acid

Thanks for all your hard work, most of us would never even pay attention to this stuff without your help.

[ajdelange]

At the risk of seeming awfully lazy I'm going to send you to http://www.homebrewtalk.com/f128/brewin ... er-198460/. I've been asked basically that question so many times that a moderator at that site asked me to summarize my philosophy on water treatment and that link is it. This is intended to get you started - not have you producing world class beers out of the gate.

The most important thing you can do is get a pH meter and monitor mash pH at dough in. So much turns on that. As for acid, sauermalz is a very good way to handle that and is very traditional in German brewing. The Brits, as we have said, typically use hydrochloric and sulfuric acids but you can use lactic or phosphoric. How much? Enough to get the pH right!

[TimmyR]

At the risk of seeming awfully lazy I'm going to send you to http://www.homebrewtalk.com/f128/brewin ... er-198460/. I've been asked basically that question so many times that a moderator at that site asked me to summarize my philosophy on water treatment and that link is it. This is intended to get you started - not have you producing world class beers out of the gate.

The most important thing you can do is get a pH meter and monitor mash pH at dough in. So much turns on that. As for acid, sauermalz is a very good way to handle that and is very traditional in German brewing. The Brits, as we have said, typically use hydrochloric and sulfuric acids but you can use lactic or phosphoric. How much? Enough to get the pH right!

Perfectly summarized and the exact point I've reached in my process to be tested this weekend. Many thanks AJ and Colin.

[Colin Kaminski]

That is a good link.

Additional sulfate will sharpen the perceived hops bitterness. Additional chloride will round, smooth and sweeten the beer. Add or decrease these in small amounts.

I would remind people that you can add CaCl or CaSO4 spiked water to finished beer and bump the SO4/Cl ratios around without rebrewing the batch. I don't fix beers this way but it does give you a seat of the pants feel for what direction to go.