acid malt

I am scheduling an American wheat and either a pilsner or helles soon and am planning a mash pH of 5.2 for both. I acidify with lactic acid but will have to use a lot more than normal to get my pH that low. Is there any advantage to using acid malt instead of lactic acid? What would be the max % of acid malt for a normal light beer style?

Acid malt is just malt that has either been coated with lactic acid, or allowed to sour naturally. I say either or because I have heard both methods and don’t know which is correct. Maybe both depending on the maltster  :-\

Rule of thumb is 1% acid malt will lower pH by 0.1. I have seen recipes with 10%, but needing to lower pH by a full point makes me think that dilution of the source water with RO/DI or distilled is a better way to go.

Thanks. I just found some of that information so it seems that using lactic acid and acid malt are pretty much the same thing. I wasn’t sure if there was a preference.

The amount is going to depend on how low you need to go.  IIRC, the general rule of thumb is 1% per 0.1 drop in pH.  So, if you needed to adjust pH by 0.5, you would need to include 5% of your grist as acid malt.  That being said, acid malt is pilsner malt with lactic acid, so if you need to acidify a lot, you could potentially get the same flavor contribution as using lactic acid.  For my wheat beer recipe, I used to use about 1mL per gallon and that was right at the threshold where I could smell it fleetingly in the finished product.  So, I switched to phosphoric and it’s a non-issue.

I know many people use phosphoric for that reason, and I have considered the change. I use so little lactic acid that I just don’t see a point until I either run out or spill my bottle. I think the most I have ever used is about 2ml for a 5 gallon batch.

Looks like 3.5 mL of lactic acid or 7.6 oz of aciduated malt would get me down from 5.7 to 5.2 for the American wheat. I have never used more than like 0.7 mL of lactic acid for my mash so 5 times as much made me think there could be ill effects.

I’ve used that much lactic several times.  No problems.

Thanks. I am a water treatment newbie so there are still a lot of things I don’t fully understand.

Same here.  It’s not until I got really close to 1mL per gallon that it became noticeable, but our water is relatively high RA.