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Acid Adjustment on Marquette Must w/KHCO3

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mattyc

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Hi -

I harvested my Marquette the other day, slowly starting to get more fruit here. I picked a little on the early side after dealing with wasps and rot last year...

pH 3.00
TA 13.5 g/L
SG 1.096

Anyhow, I have my fruit split up into three different primaries, and I went to make an acid reduction on one of the buckets. Using Potassium Bicarbonate, and trying to just knock it down about 2 g/L (and let MLF & cold stabilization take me the rest of the way - that's the idea anyway). As I understand, I should get a 1:1 reduction with the addition on KHCO3, so with 17L of must, I added 34 grams of KHCO3.

After all the foaming was over, I freeked out a little bit when I checked acid and found pH=3.9 and TA is at 8 g/L.

My hypothesis is that there is so much juice still hiding inside the berries, that the reaction took place just in the "loose" juice and that's why I'm seeing such large acid reduction.

Can anyone comment? Am I on the right track here???

Also, I have another 35 L that I haven't treated yet, so I can blend it back too if needed...
 

stickman

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The rule of thumb for potassium bicarbonate is 0.673 g/L removes 1 g/L tartrate, but as always, the chemistry can't be trusted completely, use less than you calculate and recheck often. Your not in bad shape because you have the other must to blend back if needed. I typically make 40gal batches and I will pull off a 5gal pail and make a test correction and calculate from there.
 

jgmillr1

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Hi -
My hypothesis is that there is so much juice still hiding inside the berries, that the reaction took place just in the "loose" juice and that's why I'm seeing such large acid reduction.
I'd agree with that. The yeast and enzymes will help release additional juice and the pH should drop. In the meantime you may want to hit it with the pH-appropriate amount of sulfites to protect it from the bad bugs that like high pH.
 
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