# Acid Rest?



## blackbock (27/5/07)

Hi 

I've been having some problems getting my mash pH low enough (untreated water pH nearly 8...)
and during some research on the possible remedies, I wondered whether many people have ever tried using an acid rest (instead of using, say, acidulated malt, or direct acid additions to correct the pH)

So. Is it worthwhile giving it a try? Seems easy enough. No calculations involved.


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## Weizguy (27/5/07)

Apparently, according to Palmer here, the phytic acid rest may take several hours to bring the pH to the optimum level of 5.0 - 5.5, staring with clean , neutral Pilsen water.

Maybe it would take longer with your water. I'd recommend starting with an addition of 200 - 500g acidulated malt, instead.

You would definitely have to experiment with the acid rest time to see how long it takes to get to your target pH.

If you leave the mash too long, you could start to get some lactic acid being produced by the lactobacilli which inhabit the barley husk, even though the temp is below the 50 C mark, which is about their preferred temp.

As documented elsewhere on this forum, I recently commenced an acid rest for over 24 hours, from an initial 38 C. The wort eventually dropped down to about 14 C despite insulation, and began to smell sour. This is what I was after, but it may be less than the ideal way to perform the biological process. Anyway the wort was boiled for 120 min and should have no residual acid activity.

I hope this helps.

Acid Seth 

(* edit: smelling)


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## Kai (27/5/07)

blackbock said:


> Hi
> 
> I've been having some problems getting my mash pH low enough (untreated water pH nearly 8...)



What's the pH of your mash usually?


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## blackbock (27/5/07)

around 5.9


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## wessmith (27/5/07)

Hi Blackbock, 5.9 is too high and you need to get this down around 5.2 to 5.3. Forget the acid rest as Seth indicated and go for some acidulated malt - usually around 1 to 2% of the grain bill, but this will depend on your water and the calcium content/hardness.

Wes


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## unrealeous (1/3/11)

Digging up an old thread but I'm brewing a pilsner this morning so I thought I give the acid rest a go.

I can't find much info to people doing it on the internet - most of the advice on the internet is "dont bother", "use aciduated malt", "use an acid addition", "use salts" etc etc... Even our mate John palmer doesn't recommend it "The acid rest is not used nowadays because it can take several hours for this enzyme to lower the mash pH to the desired 5.0 - 5.5 range. Today, through knowledge of water chemistry and appropriate mineral additions, proper mash pH ranges can be achieved from the outset without needing an acid rest."

But being time wealthy, adding a couple of hours to a brew day - especially all my mashing steps are now automated.

I've just calibrated the ph meter - will see how much it drops in a couple of hours

Interesting to hear if anyone still bothers using it.


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## unrealeous (1/3/11)

5.8 down to 5.5 in 2 hours... might let it run a little longer


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## Bribie G (1/3/11)

Interesting experiment, let's know how it goes - I use acidulated malt in BoPils but always interested in the old ways.


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## Thirsty Boy (1/3/11)

remember - sometimes "acid rest" refers to a ferulic acid rest when making a wheat beer. So if you were reading about "joe blow does an acid rest for all his weizens..." then they probably mean something different.

Interested to see just how long it takes to use a rest to drop to acceptable mash pH though - thanks for taking one for the team.

No concern that enough lactic action to drop the pH could also result in noticeable funky flavours?


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## blackbock (1/3/11)

Hi unrealous,

I am excited to hear about your experiment. I decided against using this technique a long time ago as it seemed to offer little advantage and lengthen an already laborious brewday for BoPils... I will be interested to hear what you think of the result. I hope you are not triple decocting as well for your sake ;-)


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## unrealeous (1/3/11)

2.5 hours - 5.8 down to 5.4-5.5

My ph meter is a bit of a cheapy - it probably +/- 0.1 at least per measurement. Next time (I'm brewing again tomorrow) I do it I'll take a sample at the beginning, put it in the fridge so I could do side by side comparisons at the end.

However, its pretty painless - I programmed in the steps - turned it on and instead of taking 2 hours to do the mash - it took 5 and a half. Checked it every now and then - seemed to be happy.

Its just landed in the fermenter now.


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## speedie (1/3/11)

we always use a three step program in mash pratice first 45-54-62 through to 71
which ever meets the fancy on the day for sacrification area
why would anyone with the malted grain of today do a decoction mash now days
speedster
ps inprove the head retension


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## speedie (1/3/11)

tb are you referring to the effects of lactobacillus
that belgium trait
no i think not 
acid rest is acid rest 
probablily not required with modern malting 

but i still include this important area of temperature mashing
enigma


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## NickB (1/3/11)

Uuuuummmmm.....

yes, well.....

Ahem.


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## blackbock (2/3/11)

speedie said:


> why would anyone with the malted grain of today do a decoction mash now days
> speedster



Possibly for some of the same reasons why they might do an acid rest! It's not always about the end result...


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## unrealeous (2/3/11)

speedie said:


> why would anyone with the malted grain of today do a decoction mash now days


I think that was asked as a rhetorical question - we might need to send speedie to on a course in punctuation. And I'm reading decoction mash as multi-step mash since there are many ways to skin a cat.

However, some good did come out of all of this - the page on decoction mashing has some stuff on acid resting.
http://www.homebrewtalk.com/wiki/index.php/Decoction_mash


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## Bribie G (2/3/11)

The wiki then goes on to say that the protein rest depends on the degree of modification of the malt, as speedie was referring to. However I assume that an acid rest can be followed by a sacch. rest and no need to do the protein rest. With pilsners nowadays I do a Hochkurz mash (three stage starting at 62 degrees - dead easy to do with BIAB) with acidulated malt. I'll have a crack at an acid rest in a couple of weeks when I do my Carlsberg-style lager. Just for the hell of it.

To the OP, I have a pack of pH strips but not a pH meter, would they be sensitive enough to monitor an acid rest?


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## blackbock (2/3/11)

Good quality pH strips and a good eye are just as, if not more accurate than electronic gizmos Bribie


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## Thirsty Boy (3/3/11)

speedie said:


> tb are you referring to the effects of lactobacillus
> that belgium trait
> no i think not
> acid rest is acid rest
> ...



No, i am referring to a rest which targets the production of ferulic acid, which is the precurser to 4VG or if you prefer, the clove tasting phenol, in a wheat beer.

The acid rest primarily being talked about in this thread is about the action of a combination of enzymatic action and the production of lactic acid by lactobacillus (motly the lacto IMO) for the purpose of lowering the mash pH.

So in fact, an acid rest is not an acid rest, it could be for two different reasons and mean one of two different things. I mentioned it only because a lot of people who step and/or decotion mash, do it on their wheat beers but not so much on other beers - and in the instance of wheat beers, there is a fair chance that any "acid" rest is supposed to be about making a beer that tastes of cloves, not so much about lowering mash pH - and they mighht be inluding the "other" acid rest as a traditional step that doesn't really exist.


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## _HOME_BREW_WALLACE_ (3/3/11)

speedie said:


> tb are you referring to the effects of lactobacillus
> that belgium trait
> no i think not
> acid rest is acid rest
> ...



Sorry to the Op'er...... Speedie mate, i think YOU! should have an acid rest......


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## Bribie G (3/3/11)

TB so if i read your comments correctly, the acid rest that was done with Pilsners in the old days was a long low temperature rest that encouraged the growth of lactobacillus and hence the lowering of the pH. 

So when using pre prepared acidulated malt (which is produced using Lacto fermentation - and boy does it taste acid - nibbled a few grains) then Weyermann have done it all for you and hence adding acidulated malt is more or less the equivalent of doing the rest in your own mash tun ?


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## Hargie (3/3/11)

...if this hasn't been mentioned already...expect around a 0.1 ph drop per 1% acidulated malt...


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## speedie (4/3/11)

tb i was under the assumption that the yeast which is used to produce a wizen style beer (wheat)
gave its esters towards the flavour components that you commented on
and an acid rest which is based around temps of 30-53 break down insoluble phytin to phytic acid


the use of a quality Ph meter is by far more accurate than paper strips

Wallace you sir are a flea!


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## Ronin (4/3/11)

speedie said:


> tb i was under the assumption that the yeast which is used to produce a wizen style beer (wheat)
> gave its esters towards the flavour components that you commented on



The clove character is 4-vinyl guaiacol, which the yeast create from phenolic acids such as ferulic acid through a decarboxylation reaction. Therefore the more ferulic acid in the wort (by doing an acid rest), the more 4-vinyl guaiacol produced and the more clove character.

I don't believe 4-vinyl guaiacol is an ester. The esters are isoamyl acetate (banana), which are formed from glucose. Therefore the more glucose in wort, the more banana flavour (theoretically)

James


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## Bribie G (4/3/11)

So would a Coopers Sparkling style with wheat and added sugar (that gets split into Fructose and Glucose) end up more estery than an all malt Coopers with no wheat?


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## unrealeous (4/3/11)

speedie said:


> and an acid rest which is based around temps of 30-53 break down insoluble phytin to phytic acid


From what I understand - The difference between a 'normal' acid rest and 'ferulic' acid is the temp. Normal are done around 35 degrees - the ferulic is done around 45 degrees.


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## speedie (5/3/11)

ok dudes and dudettes 
lets first of 
all look at the flavour components that are being put up 
if for instant you guns do a wizen batch you would be expecting the 4 vinall stuff using a wheistphan based yeast
now for a strange reaction do the same batch and use any! lager yeast with or without acid rest 
and u will have 2 very different beers
now is this due to the yeast or an acid rest?
ps my spelling is always going to be phucked
i am a doer not a wanker
wallace? B)


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## blackbock (5/3/11)

speedie said:


> the use of a quality Ph meter is by far more accurate than paper strips



However, not many homebrewers possess a 'quality' pH meter or would know the correct way to use one. Myself included. I'll stick to my strips thank you.


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## felten (5/3/11)

speedie said:


> now is this due to the yeast or an acid rest?


The yeast require the phenolic off flavour gene to create phenolics, wheat beer yeasts have this gene, lager yeasts don't.


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## Hargie (5/3/11)

felten said:


> The yeast require the phenolic off flavour gene to create phenolics, wheat beer yeasts have this gene, lager yeasts don't.




...Bingo...!


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## speedie (5/3/11)

so what i am expressing is the correct use of yeast creates that wizen style and an acid rest done in any other brew ale or lager using appropriate non wizen srtain wont produce your clove banna etc


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## Bribie G (5/3/11)

gotitinonebro


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## bconnery (5/3/11)

speedie said:


> ok dudes and dudettes
> lets first of
> all look at the flavour components that are being put up
> if for instant you guns do a wizen batch you would be expecting the 4 vinall stuff using a wheistphan based yeast
> ...


[insert swear word here] you really do have an amazing ability to tell us something that we all know and is quite obvious anyway and make it sound like you are imparting some amazing fact from the great wealth of your brewing knowledge...
A beer done with a weizen yeast and a lager yeast will be different?
My god, this shakes the very foundations of brewing? Have you posted this anywhere else? The world needs to know!


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## speedie (5/3/11)

the discssion was about acid rest 
tb point out effects in wheat beer
is that too hard for you the fathom


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## DUANNE (5/3/11)

speedie said:


> i am a wanker




could not have said it better myself


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## felten (5/3/11)

I don't fathom, your posts are too ******* hard to decipher, what a waste of time!


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## bconnery (5/3/11)

speedie said:


> the discssion was about acid rest
> tb point out effects in wheat beer
> is that too hard for you the fathom


No, the discussion was about acid rest. tb pointed out that the acid rest referred to in wheat beers was used for different effects than the acid rest the original poster was seeking discussion for. 

Regardless of this, the idea that a beer brewed with a wheat yeast and a lager yeast will be different is a. still bloody obvious and b. not actually related to acid rests, the effect thereof in wheat beers or mash ph. 

I am not even a fathom, let alone the fathom. 

Is that too hard for you to fathom?


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## Thirsty Boy (5/3/11)

I shall not bother responding to speedie - everyone else understands what i mean and "everyone but speedie" is a high enough hit rate for me.

Bribie - the common explanation for the drop in pH during an acid rest is through the action of phytase on phytin producing phytic acid (as speedie accurately pointed out) but - thats only really in quite specialized situations. Phytase is very heat liable and in anything but very very lightly kilned malts there is basically none left to do anything, and in anything but very very soft water with only a tiny buffering action, the phytic acid produced even with lightly kilned malt, just isn't enough to change the pH.

So - given that there are a decent amount of lactic bugs on your average pile of malt, and that a 35 rest is smack in the hot zone for growing them up, its my _opinion_ that in anything other than beers made with super pale under modified malt in butter soft water... Any drop in pH you notice is probably due as much if not more to lactic acid from bugs growing, than it is to phytase activity.

Not that it makes much difference - if the pH drops, it drops. The only reason to care is if you are trying to drop the pH a long way with a long rest; and you maybe risk some funky lacto favours as well as just straight acid - and lets face it, if your pH needs dropping that far, and acid rest isn't the right solution anyway.


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## gregs (6/3/11)

speedie said:


> ok dudes and dudettes
> lets first of
> all look at the flavour components that are being put up
> if for instant you guns do a wizen batch you would be expecting the 4 vinall stuff using a wheistphan based yeast
> ...



Yeah, and what you do well is; wank. <_<


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