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....
