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Old 03-18-2009, 06:52 PM   #1
batfishdog37
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Default Acid Rest

I have heard that some malts work better when an acid rest is performed. Which malts, if any, would require this?

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Old 03-19-2009, 09:10 PM   #2
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I don't think there are any. Only the weizen beer can benefit from a rest in low temperaure (40-44C), I call this ferulic rest, but some call it (incorrectly) acid rest

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Old 03-20-2009, 06:28 AM   #3
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Quote:
I have heard that some malts work better when an acid rest is performed. Which malts, if any, would require this?
I mash in at the acid rest temp (95°-98°F) for two reasons.
1. To adjust mash pH with Phosphoric acid to the required value without
rushing.
Very little conversion takes place.
I don't depend on the Phytase enzymes to lower the pH, it can take
several hours to lower the mash pH.
2. Enzyme preparation, prepares the enzymes for the hard work ahead.
Resting the mash at this temp for 30 min. improves yield regardless of base
malts used.

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I don't think there are any. Only the weizen beer can benefit from a rest in low temperaure (40-44C), I call this ferulic rest, but some call it (incorrectly) acid rest
Ferulic acid rest is different than the acid rest (temp is different).
The ferulic acid brings out more of the phenolic character (clove) of Weizenbiers during fermentation by converting it to 4VG.

The temp I use is around 113°F.

Cheers,
ClaudiusB

Last edited by ClaudiusB; 03-20-2009 at 01:22 PM.
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Old 05-02-2012, 08:17 PM   #4
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Resurrected!
I was thinking of this, I did a RIS and I think that my pH was off due to the dark malts. I think if I mash in at 115- 120 and adjust the pH I will be able to fix it before any enzymatic conversion takes place. Any one else do this?

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Old 05-02-2012, 08:43 PM   #5
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My understanding is that when pH is off due to dark malts, its usually means the mash is too acidic (low pH). If you suspect this is what is happening to your RIS, then an acid rest would be attempting to lower it further - which might not be what you want.

I'm no expert, though. I just play one on the internet.

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Old 05-02-2012, 08:55 PM   #6
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Originally Posted by mux View Post
Resurrected!
I was thinking of this, I did a RIS and I think that my pH was off due to the dark malts. I think if I mash in at 115- 120 and adjust the pH I will be able to fix it before any enzymatic conversion takes place. Any one else do this?
115-120 maybe a tad too hot for the acid rest. Actually some protien rests are conducted at 122. I use 97-100 degrees for my acid rests.
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Old 05-03-2012, 09:11 PM   #7
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Originally Posted by mjohnson View Post
My understanding is that when pH is off due to dark malts, its usually means the mash is too acidic (low pH). If you suspect this is what is happening to your RIS, then an acid rest would be attempting to lower it further - which might not be what you want.

I'm no expert, though. I just play one on the internet.
I thought this was the case as well, that the acid rest was more to lower the pH into a good range due to higher alkalinity levels in water. If you're trying to raise the pH in your RIS mash, you can toss some gypsum into the liquor to bring it up a little higher. You could also leave the darkest malts out of the mash for 45 minutes and just toss them in at the end to get all the dark goodness out of them, but after most of the stuff has converted.
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Old 03-15-2013, 04:13 PM   #8
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Originally Posted by erikpete18 View Post
I thought this was the case as well, that the acid rest was more to lower the pH into a good range due to higher alkalinity levels in water. If you're trying to raise the pH in your RIS mash, you can toss some gypsum into the liquor to bring it up a little higher. You could also leave the darkest malts out of the mash for 45 minutes and just toss them in at the end to get all the dark goodness out of them, but after most of the stuff has converted.
Gypsum will lower your mash pH, not raise it. To raise the pH, use baking soda or chalk. You need very little baking soda, say ~ 1 gram to go up by 0.1, depending on thickness. You need a whole lot more chalk, around 3 - 5 grams.
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Old 03-15-2013, 05:31 PM   #9
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Ha, crap, that's what I get for trying to use the common name. Yes, chalk (CaCO3) or baking soda (NaHCO3) is what you want, not gypsum (CaSO4). Its the carbonate ion (CO3) that will help to raise the pH. I've not used baking soda, but I know with chalk that it doesn't like to dissolve very well. Throwing it into the mash itself (instead of the liquor) will help to dissolve more of it since the mash is acidic, but you'll still have to give it 5-10 min to dissolve well and stabilize, then you can check the pH.

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