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Old 04-20-2011, 03:14 PM   #1
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Default Citric acid or phosphoric acid?

I have high carbonate water and have been treating my water with lime to precipitate out a bunch of it. I let it sit overnight and then transfer it to my mash tun and HLT. Then I use phosphoric acid to bring the pH down to ~ 6. I'm getting low on the phosphoric acid and am getting ready to buy some more and was wondering about using citric acid instead. I haven't compared prices, but assume it is cheaper (but less stable - compared to phosphoric acid).

I did a little looking through the litereature and it looks like yeast (well at least Candida) have a mechanism to take up citric acid, so I assume it would be metabolized by the yeast and therefore flavor neutral (well, at least it won't taste like citric acid).

Does anyone have any thoughts on why I might use one or the other?

Here is my typical procedure. Most of my beers are on the pale side so I figure there is enough buffering capacity in the grain to handle my now de-carbonated water at ~ pH 6. When I do brew something dark I leave the pH a little higher. I realize people always say it isn't the pH of the water, that is important, it is the pH of the mash that matters. I personally think that it is the buffering capacity that matters - as in as long as it is low there is a good chance you pH will be in the proper range. I don't like to go through the hassle of chilling hot mash and using my pH meter to check the pH of the actual mash. I do have some reasonably accurate pH test strips I use to make sure I'm in the right ball park.

I always contemplate titrating with the lime and watching for a pH jump to tell me when to stop. However, I usually remember late at night that I need to set my water so I just toss in the amount the experience has shown me works well (~ 1 tsp). I assume, that this would simply allow me to use less acid to get the pH back down

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Old 04-20-2011, 03:44 PM   #2
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I've noted here before that in the earliest days of homebrewing nearly all the recipes one saw contained some citric acid. I expect that it would be pretty strong flavor wise and I don't see how yeast would metabolize it (obvious guess in the citric acid (Krebs) cycle but that isn't operating during fermentation).

Yes, it is the buffering capacity of the water i.e. its alkalinity that determines its effect on mash pH. Assuming that you have some permanent hardness (i.e. that there is more hardness than alkalinity) you should be able to decarbonate down to alkalinity of about 1 meq/L i.e. 50 ppm as CaCO3. It shouldn't take much acid to get you down to reasonable mash pH from that level especially if you make up the calcium that got precipitated during the lime treatment. I really don't think the requisite amount of citiric acid is going to give you something that tastes citrusy but as always an experiment (i.e. determine how much citric is really required via test mash and then taste an equal volume of water with that much citric acid in it.

Another possibility is lactic which is pretty flavor neutral (until you get a whole lot of it) and is very convenient to work with in the form of sauermalz. One percent of grist lowers mash pH about 0.1 pH.

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Old 04-20-2011, 03:53 PM   #3
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From what I've seen, Phosphoric acid is used by many brewers because of it's safety (I used Hydrochloric Acid now, but will be switching soon) and because of it's neutral flavor. I think the 2 most widely-used products are saurmaltz and phosphoric acid for lowering the pH.

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Old 04-20-2011, 05:50 PM   #4
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Quote:
Originally Posted by ajdelange View Post
I've noted here before that in the earliest days of homebrewing nearly all the recipes one saw contained some citric acid. I expect that it would be pretty strong flavor wise and I don't see how yeast would metabolize it (obvious guess in the citric acid (Krebs) cycle but that isn't operating during fermentation).
That's why I asked!

It takes me about 8 ml of phosphoric acid (10 %) to get the pH down to where I want it.

I would suspect that the yeast would take any citric acid up pretty quickly.

Ok, I did a little more looking and while uptake would be quick, it is repressed by glucose, so it would probably wait until that was used up. I thought maybe the yeast could use citrate for something else other than in the TCA cycle but it doesn't look like there is much other than possibly being converted to oxaloacetate and then PEP. Although it could be used for amino acid synthesis and I assume at least some level of that is going on during fermentation

If anyone want's to see some nice metabolic pathway diagrams (very up to date) like this one, check out this link KEGG Pathway Maps What is shown is the reference pathway, but you can use the drop down menu to select saccharomyces if you want.
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Old 01-08-2012, 01:55 PM   #5
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I'm only now getting into water chemistry, and realize I'm digging up a thread here.

Did you end up using citric acid, and did you find the amount used to be similar/same as phosphoric? Was there any residual taste?

Also, is the granulated form of this at brewshops at 100%? If so, how do you mix up your required amount? Sorry if this sounds like ridiculous questions, but considering their strong power and effect, I want to make sure this is right.

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Old 01-08-2012, 03:25 PM   #6
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The 'amounts' of those acids are going to be quite different due to the strengths and the fact that the phosphoric acid is in liquid form. Unless the citric acid is adulterated, it should be 100%. You don't have to mix up the citric into a solution, but you do need a fairly accurate scale that measures into the tenths of a gram to help avoid an overdose. Citric can be added directly to the brewing water. Bru'n Water software has an acid calculator to assist brewers in figuring out how much of an acid they might need.

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Old 01-08-2012, 07:37 PM   #7
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Citric acid is made by fermenting glucose (with mold) and then filtering out the organic gunk and precipitating the citrate as the calcium salt. This is washed and then redissolved with sulfiuric acid. The citric acid then is separated from the calcium and sulfate ions using, I believe, some sort of membrane separation which should yield pretty pure stuff so I don't see purity as an issue. If you look for the stuff at health food stores it is usually labeled 100%.

Weighing anything out as a powder is complicated by uptake of moisture from the air. For precised work substances are heated in an oven and then transferred to a dessicator for cooling.

Another problem with citrate is that it is triuprotic i.e. it has up to 3 moles of protons to yield up per mole of the acid but the number actually given up depends on the pH at which one starts and at which one ends up. For example in acidifying water to pH 5.5 1.97 moles of protons are released for each mole of the acid. In acidifying to 5.9 it is 2.21 moles of protons per mole of acid. The number of moles of protons required of course depends on the alkalinity. So one has to take this into account when calculating amounts to be used.

Given all this it is probably best to just assume 2 moles of protons per mole of acid and then add the calculated amount incrementally while monitoring pH. This incorporates not only any errors from calculation but also from moisture and from any other source.

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Old 01-09-2012, 03:00 AM   #8
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Gentlemen, thanks for the reply.
First off, I'm not sure I even NEED to acidify my water but but is fairly high Ph at 9. I'd like to clarify a couple small things. I've used Bru'n which led me to this post.

On the 2nd Bru'n spreadsheet '2. Sparge Acidification' you see citric acid under acid type. What I have is the powdered citric acid from the LHBS labeled in a small plastic bag as 'Citric Acid'. On the very next sheet, '3. Water Adjustment' at the bottom where they ask for Acid adjustment, they do not have citric acid! Plus, it is only the entered as Ml/gal which further complicates it (for me).

Lastly, I have heard mention of taste thresholds in citric acid and how it can impart a fruity/estery quality . . .which I have to say I wouldn't hate if it were subtle. I had been trying to impart a slight citrus quality with hops to a golden strong but with little luck. Aroma in the fermenter was easy, but any lingering aroma and taste was nearly gone by bottling. In my head I was seeing a chance to bring down Ph slightly while possible adding a tiny bit of citrus even though it may not be common home brewing flavoring agent.

My water:
Ph 9%
Alkalinity/Bicarbonate (HCO3) 33 ppm
chloride (Cl-) 9 pm
sodium (Na+) 6 ppm
sulfates (SO4-2) 32 ppm
calcium (Ca+2) 27 ppm
hardness (around 45-50?)
magnesium (Mg+2) 6 ppm

7.5 gallons total water, ~1/2 in cooler MT with 10lbs all pale/pilsner (golden strong-trippel), rest in BK. Drain off mash into bucket, then dunk sparge bag in kettle. Kettle water at 165. I may change this to just do a second batch sparge of total remaining volume.

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Old 01-09-2012, 04:08 AM   #9
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Those numbers don't quite line up. For example, those levels of calcium and magnesium give a total hardness of 92 if interpreted as mg/L as the ion though they give a total hardness of 33 if interpreted as CaCO3. Not sure whether you mean alkalinity or bicarbonate under that listing though at pH 9 the two are actually almost equal. But in any event I can't get the profile to balance at all well under any set of assumptions I can come up with. Be that as it may, assuming that the alkalinity is in the 30's you should not need to acidify sparge water. But should you decide to the following amounts of 100% citric acid would be required per liter of water treated

Target pH ........ mg/L
6.00 ............. 18.9
5.80 ............... 22.4
5.60 ............... 25.5

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Old 01-09-2012, 05:00 AM   #10
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As I mentioned in my earlier post, learning water chemisty is all new to me. I've reread your post several times, and afraid I don't understand. Under the alkalinity/ bicarbonate line, it very well may be a mistake and is just bicarbonate. I think i copied that down wrong.

From everything I've read and the Bru'n spreadsheet, it seems all I need is some calcium chloride. My last two batches had an astrigent quality that may just be young beer so far, but it seemed to me I was getting tannins or hop over-utilization or something. I was wondering about the acid, thinking maybe the higher ph in the dunk-sparge was causing problems.

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