Author Topic: Acid rest calculations  (Read 2625 times)

Offline john2367

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Acid rest calculations
« on: April 26, 2021, 10:25:47 AM »
Hi all,
Recently, I?ve been having problems with the clarity of my finished mash prior to transfer to the kettle.
I?m using the same methods, same grain supplier and yeast, but the beer is taking a lot longer to clear and even using gelatine hasn?t helped tremendously.
I?m using Beersmith to correct my ph and aim for 5.3 in an English bitter. This involves about 9 ml of AMS to achieve the correct alkalinity.
I?m beginning to wonder if  it?s the pale malt supply that?s causing the problem.
I was wondering if an acid rest/glutamate rest would be worth trying to see if it helps. If I did an acid rest to supply the acid has anyone any idea how to allow for this in my calculations? How would I calculate the added acid?  I obviously don?t want to drive the ph to low.
Thanks to you knowledgable people.........

Offline Oginme

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Re: Acid rest calculations
« Reply #1 on: April 26, 2021, 12:38:53 PM »
First, I would not sweat a turbid liquor going into the kettle.  It really has no major impact on the ending clarity of the finished beer.  I do BIAB and regularly have some turbidity of my wort, most of which settles out with a good hot break at the beginning and cold break when chilling.  That and a clarifying agent such as Irish moss, Whirlifloc, super moss, etc. will cause the proteins to flocculate and settle out of solution.

Having said that, if you want to incorporate an acid rest, then I would start by holding back some of your usual acid, maybe 20% to 25%, and then taking a pH measurement around 10 minutes into the mash rest and determine if and how much of your remaining acid would be required.  Realize that the mash pH range is pretty broad 5.2 to 5.8, and I have even gone down to 4.9 without any issues other than needing a slightly longer mash time to convert.

Recycle your grains, feed them to a goat!

Offline BOB357

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Re: Acid rest calculations
« Reply #2 on: April 26, 2021, 09:59:56 PM »
As Oginme stated, clear wort into the kettle doesn't negatively affect the quality of your final product. The same holds true for clear wort into the fermenter. Many brewers dump the entire kettle content into their fermenter and still make great beer.

RDWHAHB
Bob

Offline john2367

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Re: Acid rest calculations
« Reply #3 on: April 27, 2021, 04:07:39 AM »
Thanks to you both for your comments and re-assurance.
I possibly am worrying to much about mash clarity; it just seemed to coincide with a very marked downwards efficiency in post fermentation clearing even using finings.
I?m brewing again next Monday so will try the acid rest together with accurate ph measurement to rule out the pale malt suspect and report back,
Many thanks😜

Offline Oginme

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Re: Acid rest calculations
« Reply #4 on: April 27, 2021, 06:02:22 AM »
Hmm, the downward change in efficiency (I am assuming we are looking at mash efficiency and not brew house efficiency which takes into account other process losses) may or may not be connected with the turbitiy of the wort.  So the questions I would have are:

a) What is your mash pH and how are you measuring it (when/what temperature/device)?

b) Do you perform a starch-Iodine test for completeness of conversion?

Recycle your grains, feed them to a goat!

Offline john2367

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Re: Acid rest calculations
« Reply #5 on: April 27, 2021, 01:11:17 PM »
Hi Oginme,
My ph was 5.4 so well in there. I didn?t perform an iodine end of mash test so I can?t be certain that the mash was completed in full. I think the next brew due next week will be strictly controlled in terms of acid additions, ph and mash completion steps.
I will report back on observations,
With thanks, John