The general consensus seems to be that a mash pH of 5.2-5.6 is desired. Beersmith even says it's the difference between a good beer and a truly great one.

Most mention trouble with too high of a pH, but I'm wondering, what are the impacts of a much lower pH, like 4.5 or even 4.0?

I ask because adjusting the pH to make the environment favor lactobacillus using acidulated malt would be a pre-mash way of lowering the pH (rather than a post-mash method like adding phosphoric or lactic acid). I would prefer to use the acid malt, but it is pre-mash, so would like to understand the consequences.

At least according to this experiment, there's not much negative impact, but it's hardly definitive.

1 Answer 1


The enzymes beta-amylase and alpha-amylase have ideal ranges. Doesn't mean they will not work they just take longer if a little too high or low.


Basically what it says is that our brewing enzymes will still function until pH induced denaturing, which happens around pH 2.0 Though they lose a lot of functionality below 4.0 pH.

But for your application I would mash normally until saccrafication is done then add your acidulated malts at the end. Sparge once you've reached your desired pH.

  • But then you lose the conversion of the malt, but still probably preferable to adding acid directly.
    – Wyrmwood
    Jun 12, 2018 at 21:57
  • 1
    @Wyrmwood acidulated malt is made by fermenting the kilned malt. For that to happen the sugars in the grain have already been made and mostly used by the lactobacillus, making the acid. I suspect Mashing late just to drop the pH would have little effect on OG. Jun 12, 2018 at 22:49
  • Just one last nitpic - the article suggests the enzymes are still functional between 4.0–9.0 but your suggestion is still to add the acid malt post mash, why?
    – Wyrmwood
    Jun 13, 2018 at 15:01
  • @Wyrmwood I suggested just in the interest of reducing your mash time. Jun 13, 2018 at 16:25
  • There is a table floating around out there that depicts Alpha/Beta amylase activity by functions of temperature and pH. I think John Palmer had it in his book "How to Brew"
    – mreff555
    Jun 13, 2018 at 19:35

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