Mash pH Question (water report included!)
So as a professional science geek (molecular bio) I'm surprised that I haven't spent more time in this forum until recently. I emailed my local water authority and asked for the water report for my address, to which I got an awesome reply (I guess the water QA/QC get excited when you take an interest in their work). Here it is:
Thanks for your help!
Looks like you have soft water there which is probably good for brewing most lite beers. My profile is very similar.
As far as the necessity to acidify the mash, that doesn't necessarily need to be done. When you add the malt is greatly impacts the acidity and usually drops it. It also really depends on what type of beer your making and what kind of malts your using. Dark malts tend to drop the acidity down a lot and generally people try to compensate for that.
Also, acidifying the mash doesn't necessarily impact the flavor. Generally you want your mash to be between 5.0 to 5.8 ph. This is where the enzymes are most comfortable working. Also what end of the range you are in matters too. One end is more fermentable wort and one is less because alpha and beta amylase function better at different pH's. I cant remember what right now but it's easy to look up.
Adding CaCl might help out your beers. Calcium is an important mineral for yeast. Cl can help bring out the malt profile in beer too.
Gypsum adds calcium and sulfates to the water. Sulfates are what helps bring out more of the hop flavor.
I really suggest reading up on all this stuff. There are also calculators you can use. Ones that are popular are:
http://www.ezwatercalculator.com/ (which i believe Palmer had a hand in)
I would check out both and read up on the water knowledge in bru n water
You are fortunate in that you have low mineral water in the sense that you will not have to concern yourself with reducing the content of any ion which is harder to do than increasing which is done simply by adding salts. You will want to do that in many, but not all cases. There is rule of thumb that says you should have at least 50 mg/L calcium and that's probably a good working number for most beers but if you get interested in Helles or Bohemian Pils you can do them with the water you have without treatment and they will be quite traditional. Adding some chloride will sweeten them, round them out and make the body fuller so I usually recommend adding some calcium chloride to water like yours. Thus, IMO, the common advice to add CaCl2 is sound not so much because of the calcium but because of the chloride though the calcium has its beneficial effects too unless you want a really 'soft' tasting beer (like Helles or Pils).
An easy way to find out what sulfate does to flavor is to take a relatively hoppy beer that has been brewed with low sulfate water (like a Pils) and add some gypsum in the glass. A better way is to brew 2 identical beers except for the sulfate levels and comparatively taste them.
Whether sulfate 'improves' hop flavor or not depends on lots of things including the palate of the taster. I don't like the effects of sulfate in general, nor highly hopped beers unless they are made with low to moderate sulfate levels. There are plenty of other people with the opposite view who love beers made with water above the EPA secondary MCL for sulfate. You will have to find out where you lie in this spectrum by experiment.
You will need acid for most of your beers - even some dark ones. The goal is to get the pH of the mash (measured at room temperature) to around 5.4 or 5.5. Most base malts have a distilled water mash pH of 5.6 - 5.7 and an average buffering capacity of about 21 mEq/kg-pH. Crystal and roast malts have lower DI mash pH's and buffering capacities which differ from the average but I think you will find that unless the beer is quite dark that some external acid will be required to get mash pH into the desired range. This is critically important as there are hundreds (thousands?) of reactions going on in the mash and only when the pH is in the right range do all the subtle flavors synergise to produced produce an "Ah" from the drinker.
Given your background and employment an obvious suggestion for mash acidification would be hydrochloric acid which I do not recommend to untrained brewers. It will both lower the pH and boost your chloride level. If you find you are a sulfate buff, sulfuric is obviously a possibility for you. In the UK it is common practice to use a blend of sulfuric and hydrochloric acid (sold commercially as CRS) for elimination of bicarbonate (not a problem for you) pH reduction and enhancement of sulfate and chloride. For most brewers I recommend lactic acid, particularly in the form of sauermalz as the malt itself lends some interesting but subtle flavors, or phosphoric acid which is flavor neutral and I recommend them because they are all available at homebrew supply shops in dilute, food grade form.
All this can be bewildering at first. You might want to look at the Primer in the Stickies for some ideas on how to get started. Your water is low enough in minerals to be used with the Primer's recommendations without further treatment (dilution).
Thanks so much for the replies guys!
Hopper: Those calculators look really helpful, thanks for the links. As far as reading up on the subject, I think I'll take a look at the stickies, I've looked at Palmer's chapter on water in my copy of How to Brew, yet I think that his focus on color as a function of water composition is a little off, as I've seen others state in this forum. Thanks again for the links.
AJ: I've yet to try and make a Pils or Helles, but I'm glad that my water is soft enough for either, as I'm toying with the idea of a Pils soon; I've just finished brewing an IPA and oatmeal stout, and I'm in the mood for something lighter now. As far as the sulfur content goes, I would assume all of my IPA's and pale ales have been made with low sulfate levels, so I think next time I'm going to try and add some sulfate via gypsum and see if I like the difference.
Regarding mash pH, I agree that I'd need to lower it, as the alkalinity of my water isn't enough to overcome the buffering capacity of the mash and bring the pH down to acceptable levels (is this correct?) I have access to both HCl and sulfuric acid, but I haven't done any buffer system calcs in a while and would be a bit rusty. Is there a resource online for help with this? As far as safety is concerned I'm not worried, as I use both of these (conc) to make buffers at work (protein expression via insect cell cultures).
Thanks again for your help!
acid_requirement = (target_pH - DI_pH)*buffering_capacity*wt_grain.
For example, if you want pH 5.4 and are mashing 5 kg Maris Otter which has a DI pH of about 5.6 the acid required would be
acid_requirement = (5.4 - 5.6)[pH]*(-21)[mEq/kg-pH]*5[kg]= 21 mEq
for the Maris Otter alone. If you have 1 kg of a grain with a DI pH of 5.1 the requirement is
(5.1 - 5.4)*-21*1 = -6.3 mEq
You do this for each malt and sum up the results. If the sum is positive you add that much acid. If negative you add that much base.
Weyermann maltings has a rule of thumb that says 1% (w/w) sauermalz in the grist lowers the pH 0.1 unit. The -21 mEq/kg-pH number is derived from that rule of thumb assuming that sauermalz is 2% lactic acid w/w. Using that rule of thumb is certainly easier than the calculations.
There are also lots of spreadsheets and calculators which will do this for you though I am not sure about what the algorithms are for any of them. Or to be more honest about it, I haven't a clue. Some of them try to back things out from malt color, for example.
Obviously to do the job right you need to know the DI mash pH and all the pertinent Taylor series terms for each malt. I have no assurance that 2 terms are enough but I am certain that there is appreciable deviation from the -21 mEq/kg-pH value with some malts.
Rather than deal with the uncertainties I recommend making a test mash and measuring the pH of that. You can certainly use any of the spreadsheets or calculators to get you in the ball park but IMO the final determination should be based on measurement.
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