Acidulated Malt And Acid Rest?

[Ash in Perth]

Gday.
I checked my water pH with an aquarium pH kit and it it about 7.5-8. Rather than get into pH adjustment, for now i thought i would give acidulated malt a try. Ill be using it as about 5.5% of the grist in an APA mash. Do i need an acid rest incorporated into the mash? If so, what temperature and for how long before the Conversion rest?

Cheers for your help

 

[JasonY]

If you are adding acidulated malt then an acid rest shouldn't be needed. I believe the grain will drop the pH with darker malts acidifying more.

I have only used acidulated malt in pilsners so far at about 3.5% of the grist so no real expert on this. Depending on your grain bill the mash pH may end up closer than you think.

 

[wessmith]

Ash, you dont need an acid rest with acidulated malt. And I would reduce the amount to 2% from looking at your water pH. That should land you around pH5.3 in the mash tun.

Wes

Gday.
I checked my water pH with an aquarium pH kit and it it about 7.5-8. Rather than get into pH adjustment, for now i thought i would give acidulated malt a try. Ill be using it as about 5.5% of the grist in an APA mash. Do i need an acid rest incorporated into the mash? If so, what temperature and for how long before the Conversion rest?

Cheers for your help

 

[Ash in Perth]

Thanks guys. Ill do that.
It is 85% JW ale malt, with about 5% of each crystal and wheat malt along with the acidulated.
I dont fully understand what happens during the acid rest.

 

[MHB]

Ash
During the acid rest, bacteria on the malt (Lacto Bacillus) become very active, they make lactic acid, the acid changes the pH of the mash; carried to extremes you get sour beer (see Weizguy).
Acidulated malt has been held at the right temperature for the Lacto to go off, then the grain was kilned, stoping the bacteria, when dried the grain has lots of natural lactic acid.
We are just using this acid to lower the ph.

Its a way to get around the Reinheitsgebot otherwise adding the right amount of acid would do.

MHB

 

[Ash in Perth]

Ahh so its a biological thing nopt chemical. Thanks for clearing that up for me.

Does this mean if you wanted to get the mash pH exact, you could sit at acid rest temps until the pH was around 5.5ish and then raiuse the temp? (assuming i had a really good pH meter, which i dont)

 

[MHB]

Ash
You have to look at it from two points of view.

Adding Acid
Acid is Acid doesnt matter where you get it, adding acidulated malt is adding acid.
Some acids (and bases) are buffers, loosely they have a natural pH and they dont like changing. Lactic is like this so is Phosphoric Acid.

The good thing about Lactic Acid is you dont have to be exact with your doses, close is good, but it is more tolerant of variation it tends to sit at about the right pH.
A strong acid (i.e. Hydrochloric) can cause huge changes with very small additions, this makes it a lot harder to use with out as you mentioned a good pH meter. You can add too much even of a week acid and still over shoot the pH you want, it is harder but doable. Thats why Wes Smith recommended a smaller acid malt addition.

Making Acid
This is a natural biological process where you are allowing the acid to form in the mash.
Because Lactic Acid is naturally buffering at close to an ideal pH, it is relatively easy when you are doing an acid rest to hit your target, and a lot harder to get too acid, the big drawback is that its time consuming.

Hope his helps

MHB

 

[Tony]

I have read lots on acid rests and decided that i dont have the time when 2 to 4% acidulated malt in a pale beer seems to help.

I used it in ly last brew, a pale lager.

76%JW pils
10% JW wheat
10% TF flaked maize.
4% weyermann acidulated malt

my water is about 7.5 to 8pH and i hit 5.2 pH with this combo.

the darker the beer the less you need.

I recon with a beer over 16 EBC you wouldnt need any.

When you get into stout range you need chalk to raise the pH as the roasted malt loweres it to much apparently.

Will be testing this theory soon with a stout

cheers