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Old 03-08-2009, 06:38 PM   #1
TheChemist
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Default pH and Brewing Liquor (water treament and brewing salts)

k guys, I only kinda-sorta know what I’m talking about, so input and corrections are always welcome. The concepts I’m going to touch on go waaaay deeper than what I mention, and I encourage you to go ahead and check out the hardcore science, because it’s pretty nifty.


Disclaimer: I understand the importance of water composition and pH far better than I used to, but I am still unconvinced that home brewers need to go to such lengths for their beer. If you’re into this that’s great, but if you think it’s just too much hassle I’m sure that your beer won’t die a horrible death just because you skipped the brewing salts.
*hides from hardcore home brewers who will now want to yell at me for
speaking such heresy*


WARNING: HIGH SCHOOL CHEM THROWBACK (you’ve been warned )


pH
As it was in my experience, pH is one of those things that few first-time brewers would know to consider. Turns out, to my surprise, that it’s one of those super-important things to consider for several different parts of the brew process (mashing, yeast flocculation, hop utilization, etc.).

pH is all about the presence of hydrogen ions in a solution. When hydrogen loses its single electron, it’s really just a lone proton. The actual pH measurement is a logarithmic equation of proton concentration (ranging from 1-14, 1 being more acidic, and 14 being more basic). Pretty much, it’s a ratio between the presence of H+ (hydrogen ion, which is also called a proton) and OH- (hydroxide). The higher the concentration of H+, the lower the pH value (acids). The higher the OH- , the higher the pH value (bases).


In Mashing

There are lots of reasons why pH matters, but it is perhaps most important in mashing and enzyme function. With extreme pH in either direction, you pretty much have a boatload of charged particles floating around in the solution. Now, enzymes (which –among other things– are responsible for converting starches from the grain into sugars) are usually protein structures, which means they’re a bunch of amino acids strung together. So the physical structure of an enzyme is dependant on the charges of various sites within the protein coil. If enzymes are in a solution with the wrong kind of charges, the physical structure of the receptor sites (which is where starch attaches to be broken down into smaller sugars in mash) is actually warped, and the enzymes are unable to function properly.

What this all means in practical use is that if the pH of your mash isn’t right, the enzymes aren’t going to work as well and you’re not going to get as much sugar out of your mash as you should (ie. bad pH = less potential alcohol).

Your pH will also affect tannin, protein, oxalate, colour, and flavour extraction from your mash. So when you have a lower pH in your mash, the final product (ie. beer) is less astringent (the result of tannins), less hazy (proteins and oxalates), and has less colour and malty/grainy tastes.


The important enzymes in mash (α amylase, β amylase, and proteases) function best in the ranges of 5.3-5.7, 5.1-5.3, and 4.6-5.0, respectively. Since these don’t happily coincide with each other, we have to compromise a bit on what our mash pH should be around. I’ll discuss what I’ve been instructed to do in order to achieve optimum pH for your mash, boil, and fermentation in the water treatment section of this post.

Darker malts are actually more acidic (because they’ve been kilned longer) so if you don’t want to bother with water treatments but you’d like to help your mash a little, try tossing in 1-2% of chocolate or black malt to decrease the pH.


In Boil and Fermentation

I know decidedly less on this topic, though I might add to what I’ve put here in subsequent weeks when my course gets to hops, yeast function, and fermentation. Pretty much, all I know at this point is that a slightly acidic wort means that you don’t get as efficient utilization of alpha acids from hops in boil, but that same slight acidity in fermentation helps encourage yeast flocculation. So all-in-all, a slightly lower pH in a beer seems to be a generally positive thing.


Desirable pH’s

I’m not sure how loyal you want to be to these, but here are a couple of general guidelines for pH in the brewing process;

Brewing liquor – pH 6.2-6.6
Pre- boiled wort - ~pH 5.5
Post-boil wort – ~pH 5.2
Finished product – pH 3.9-4.2



Brewing Liquor (water treatment)
Now that we’ve established why pH is so important, let’s discuss what we can do to help out our friendly neighborhood enzymes and other hard working chemical components of brewing. I’ve learnt about all this in terms of commercial use, but I’m going to try and avoid the non-related topics (like drawing from local groundwater sources).


The ol’ double H ‘n O

When looking at water, you want to be sure that it’s free of toxins (like pesticides, chemicals, and heavy metals), microbial infections (little critters), and that it has low levels of dissolved solids. In my experience commercial water treatment will take care of those because of government regulations, so your tap water should be safe (unless you live in Mexico or somewhere else where water quality is an issue). When discussing water treatment, it’s ideal to know the basic analysis of the H2O you’re using. As home brewers, this might be a bit harder; I suggest seeing if your local water company has the information available, or using bottled water that has the information available.

Water is generally a neutral (pH 6-8) solution, but can hold a host of different salts (ions in water) that will change the pH when boiled, and will also interact with enzymes and yeast, which will ultimately affect the efficiency of your mash and final attenuation. An untreated mash with distilled water will generally settle around a pH of 5.8.

Salt concentration in water is spoken about as ‘hardness’ or ‘softness’; soft means less salts, hard means more. There are three kinds of hardness to be considered in brewing; temporary, permanent, and hardness due to sodium carbonate. That last is fairly difficult to treat without specialized equipment, so not much can be said about its treatment – water with high levels of sodium carbonate will sometimes mean that you have to use recipes that are more alkaline tolerant.

Temporary hardness is caused by calcium and magnesium bicarbonates, and will cause water to become more alkaline, especially when boiled. This is because when these salts are aqueous they release several ions, among them hydrogen carbonate (HCO3- aka bicarbonate) which then reacts with protons in water to produce water and carbon dioxide.
Eg.
Ca(CO3)2 (aq) ==> Ca2+ + CO2 + HCO3- + CO32-
HCO3¬¬- + H+ ==> H2O + CO2
So bicarbonates use up the supply of H+ in water, which means that the ratio between H+ and OH- changes, effectively raising the pH (making the water more alkaline). It also has a nasty habit of ‘furring’ your kettle, and using up calcium ions in the water – all in all, a bit of a pain in the butt.

Permanent hardness on the other hand, is a result of calcium and magnesium sulphates, which makes the water more acidic (I’m not sure how – we haven’t gone over that, since it’s a happy effect anyway) and also interacts with enzymes and yeast to stimulate activity. Calcium sulphate is also known as gypsum, and is a commonly used brewing salt, along with calcium chloride (more on those later).

So as brewers, we want to decrease our pH and toss in some extra calcium, sulphate, and chloride. As I’ve been taught, acid is generally added to the brewing liquor (for pH) and salts will be added to the griss case (dry grain), all of which will ultimately affect the enzyme and yeast activity in your beer.



In the Hot Liquor Tank (boiling water for mash and sparge)

The most common acids used to treat your water for mash and sparge (aka brewing liquor) in commercial breweries are hydrochloric acid (HCl), sulphuric acid (H2SO4), and occasionally lactic acid (C3H6O3). This will generally depend on your suppliers, but the calculations that I’ve learnt use H2SO4. This treatment is exclusively to counteract the bicarbonates in the water, and therefore decrease pH (increase acidity – yay!).


In the Grist Case (dry grain before mashing)

This is where you add your brewing salts – mix ‘em in well! The reason that gypsum is added with the grain is twofold; first, very little will dissolve in hot water so you may end up losing those solids at the bottom of your kettle when you go to transfer water (CaSO4 and CaCl (the salts that I’ve been taught to use) only dissolve a tiny bit in water; the ions in the water then go on to react with phosphates in the grain, which leaves more ‘room’ in the water for more salts to dissolve and then react.). Secondly, since they’ll remain solid for a good portion of the mash, mixing ‘em in with the grain ensures that the salts are evenly distributed throughout the mash.

*blushes at how long this thing is*
continued in next post....
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Old 03-08-2009, 06:39 PM   #2
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Default pH and liquor continued...

Salts and Ions in Your Beer

The salts that you add, in addition to helping enzymes and yeast, also affect the taste of your final product. The tastes that you’re going to notice are; sour/salty from higher levels of sodium and potassium, dry/bitter from sulphates, a mellow taste from calcium, and maaaaybe a bit of bitterness from magnesium if there’s not a lot of calcium to cancel it out. Salts can be changed according to what style of beer you’re making to affect overall taste (eg more Cl for stouts, more SO4 for IPA’s)


Ions do other things too….

Calcium (YAY!)
- affects pH depending on if it’s in carbonate (raises) or sulphate (lowers) form
- stabilizes amylase (>50mg/L), and stimulates amylases and proteases
- encourages clarity and limits extraction of colour and tannins from the malt

Chloride (YAY!)
-improves clarification and provides mouthfeel (don’t go over 400ppm though!)

Sulphate (YAY!)
- encourages mash reactions, and increases dryness and bitterness
- facilitates filtration/removal of haze

Magnesium (HMM…)
- just like calcium, only half as effective
- co-factor to some enzymes, brings impure or astringent flavours if more than calcium

Sodium (MEH)
- increases mouthfeel (75-150ppm is acceptable)
- sour/salty taste, and inhibits malt germination (which means less sugars available)

Manganese (MEH)
– co-factor for some enzymes

Flouride (MEH)
-actually, doesn’t do anything in brewing, but can make your teeth enamel harder =D

Iron (BOO!)
- colours beer (think rust – mmm, tasty), flavours tannins, and forms haze
- slows yeast (at >0.2ppm) and reduces starch breakdown

Nitrates (BOO!)
-high levels indicate sewage pollution (eeew!)

Potassium (BOO!)
- >10ppm – inhibits enzymes and makes your beer a laxative




Calculations
So really, you can just ignore everything else before this part, because it’s all just theory. Here are the calculations that I’ve learnt for water treatment and brewing salts. Be sure to take care with your units!!!

But first, here are a couple charts that indicate useful ranges of concentrations according to beer style (feel free to tinker with the numbers to suit what you want out of your beer). These are the two charts I have – I can’t account for the differences in numbers (I might ask my teachers though…)

Desired for Beer Styles
Ions in mg/L Na K Mg Ca Cl SO4 CO3
Lager 18 2 3 20 25 33 18
Bitter 35 4 20 130 150 260 20
Mild 50 4 20 75 250 120 20
Porter/Stout 12 4 10 30 200 120 20

Typical liquor analysis
Ions in mg/L Ca Cl SO4 CO3
Lager 50 10 10 <25
Bitter 170 200 400 25-50
Mild 100 300 150 50-100
Stout 100 300 100 100-200


Acid Calculation

(Available alkalinity – Desired alkalinity) x Volume in L = mg of alkalinity that needs to be removed

The alkalinity of your water should be available from the local water treatment plant - it’s actually the CO¬¬3 concentration in the water. Depending on the concentration of the acid you’re using (it’s usually 25% commercially – be sure to wear face protection for acid that strong!) you can then figure out how much material you need to add to your liquor. 25% sulphuric acid removes 291.62mg/ml of alkalinity.

Example:
A brewer is making a 20L batch of a bitter, and his local water alkalinity is 145mg/L. His buddy works at the local microbrew, and can slip him some 25% H2SO4 provided he wears a face mask when handling it.

Actual alkalinity = 145mg/L
Desired alkalinity = 25mg/L
Volume = 20L

(145mg/L-25mg/L) x 20L = 2400mg
2400mg / 291.62mg/ml = 8.3ml of 25% sulphyric acid to add to your hot liquor


As you can see, the actual amount of acid that you need to add for a batch is really tiny – hence why so few home brewers bother with it. You could always just add a couple percent of dark malt (chocolate or black), which will also decrease pH – in my mind, that sounds lot easier than dealing with acids, but that’s just me.


Brewing Salts

(Desired element – Actual element) x Volume in L = mg of element to be added

Something to keep in mind with Ca – you almost always get a surplus just with the Cl and SO4 additions, so you don’t really need to worry about it. The percentages of elements are based on atomic mass – back to high school chem.

CaSO4•2H2O has 56% sulphate, 23% calcium
CaCl2 has 64% chloride, 36% calcium

Example:
That same brewer wants to add some salts too, just for kicks. Remember, he’s making a bitter.

SULPHATE
Desired sulphate = 250mg/L
Actual sulphate = 75mg/L
Volume = 20L

(120mg/L-75mg/L) x 20L = 3500mg of sulphate
3500mg x (100/56) = 5469mg of CaSO4

CHLORIDE
Desired chloride = 170mg/L
Actual chloride = 30mg/L
Volume = 20L

(170mg/L-30mg/L) x 20L = 3000mg of chloride
3000mg x (100/64) = 8545mg of CaCl2

CALCIUM
Desired calcium= 150mg/L
Actual calcium = 100mg/L
Volume = 20L

(150mg/L-100mg/L) x 20L = 1000mg of calcium

8545mgCaCl2 x (36/100) = 2874mg calcium
5469mgCaSO4 x (23/100) = 1258mg of calcium

(2874mg + 1258mg) – 1000mg = 3132mg

There is a surplus of 3132mg of calcium – no need to add more :P

Add 8.5g of CaCl2 and 5.5g of CaSO4 to your grains before mashing!




So, I think that’s actually everything I have on pH and water treatments….
That’s an awful lot though – let me know if any of this makes sense, please!
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Old 03-09-2009, 01:42 AM   #3
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That's a lot of big talk for your first few posts!

Seriously, that's very good information. What are your textbooks?

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Old 03-09-2009, 06:27 AM   #4
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Location = Cowtown?????

Serious first post. Evar.

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Old 03-09-2009, 07:41 AM   #5
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Quote:
Originally Posted by TheChemist View Post
That’s an awful lot though – let me know if any of this makes sense, please!
Makes perfect sense! In fact, the hypothesis you're describing is basically what I've been doing (adding calcium salts), but if I had read this thread six months ago, I'd have been doing it a lot sooner.

A third way, one might assert, to lower mash pH is an acid rest.
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Old 03-09-2009, 02:52 PM   #6
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Very cool TheChemist.

Any problem with this:
I don't use any acid...just salts.
I base my target residual alkalinity on the color of the beer I'm brewing (i.e. the color contributed by the grains...not syrups/extracts/etc.). Doing that just gives me a ballpark guess for the acidity contributed by the grains so I can devise a water recipe (with the appropriate residual alkalinity) to hit my mash pH.
Then I dilute with distilled if I need to reduce alkalinity (I usually do).
Then I add the salts to get my target residual alkalinity.
My mash pH has always been between 5.0 and 5.4 doing this (I also do an acid rest for really light brews).

Unless it's a pretty dark brew I usually end up diluting with distilled and adding CaCl, CaSO4, and MgSO4 at a ratio of 4:2:1 (most brews) or sometimes 2:1:1 (really light brews where I've cut my water so much I need some Mg back).

Regarding adding the salts to the grain:
When I make dark brews I treat the mash water but not the sparge water. That way I don't have to worry about the sparge pH getting too high.

But when I brew anything BUT dark brews I treat both the mash and sparge water to try and prevent the sparge pH from getting too high. But I have found that if I pay close attention to my dilution rate that I don't have to add too much salts.

So far I have only been trying to hit a mash pH of 5.1-5.5 regardless of style. I've done from Stouts to Helles and the mash pH was in that range...but I haven't tasted all of them yet (so jury's still out).

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Old 04-02-2009, 09:35 AM   #7
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Where can the common man buy HCL. I need to lower my ph some for brewing low srm brews like pilsners. I know Muriatic acid is HCl but I doubt the stuff you can get at a hardware store is high enough quality to be using in the mash.

I have come across Betaine HCL supplements. I have no idea what the % of HCL is in 500mg.

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Old 04-02-2009, 02:01 PM   #8
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Quote:
Originally Posted by Denny's Evil Concoctions View Post
Where can the common man buy HCL. I need to lower my ph some for brewing low srm brews like pilsners. I know Muriatic acid is HCl but I doubt the stuff you can get at a hardware store is high enough quality to be using in the mash.

I have come across Betaine HCL supplements. I have no idea what the % of HCL is in 500mg.
I'm not sure why we still use the term "muriatic acid", since it is hydrochloric acid. Muriatic is just an old timey term. Some have said there are differences in the HCL:H20 ratio, but even acids labeled as muriatic differ in their proportion of HCL from source to source.

There are 3 grades of HCL... food-grade, reagent grade, and electronics grade. You might find a food-grade HCL (or "muriatic acid") at a pool supply store, since it is commonly used to control pH in pool water. Not sure though... just a thought.
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Old 04-02-2009, 11:05 PM   #9
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Quote:
Originally Posted by Denny's Evil Concoctions View Post
Where can the common man buy HCL. I need to lower my ph some for brewing low srm brews like pilsners. I know Muriatic acid is HCl but I doubt the stuff you can get at a hardware store is high enough quality to be using in the mash.

I have come across Betaine HCL supplements. I have no idea what the % of HCL is in 500mg.
If you must use acid I think you are better off using lactic or phosphoric acid. Most brew/wine suppliers should have lactic acid. Both of those products are less aggressive than hydrochloric acid and a more natural fit with a food product like beer. That said, I would only use acid as a last resort. Assuming you can obtain or create appropriate water for the beer style the mash pH should take care of itself without an acid addition. For pilsner use water that is very soft, with virtually no sulphates then add a little calcium chloride to get the Ca+ level up to 50/75 ppm and you should be good to go.
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Old 04-02-2009, 11:41 PM   #10
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Acid malt is a much better option to decrease the pH of the mash as opposed to adding stong acids or dark malt(wtf?). Calcium and Magnesium are also much better options.


I'd be interested as to what course yo are taking...

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