Help with testing for acid in muscadine must. - Home Brew Forums
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Old 08-30-2011, 03:19 AM   #1
crj5000
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Mar 2011
Orlando, Florida
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This is the first time that I have tried to use an acid titration kit. It has the sodium hydroxide and phenolphaliene. The directions say to take 15 cc of must and 3 drops of phenolphaliene and mix well. Take 10 cc of sodium hydroxide and slowly add and stir until the color does not change anymore. The directions say that the color will go from blue to gray to black. I picked the muscadines from my grandmothers vine and it is a red skinned muscadine. The juice is still clear since the skins have only sat in the must for 24 hours. Here are the results: I stirred the solution everytime I added sodium hydroxide.

cc - color

3 - Clear
4 - Dark Blue
4.5 - Dark Blue
5 - "Little Darker Blue"
6 - Same color as 5
7 - Gray
8 - it now has a clear look to it, so I called it "clear gray"
8.5 - Same as 8
9 - Same
10 - Same

My question is, what is the TA for this must? Is it 6 since dark blue is closer to black than gray is? Or is it 7 since Gray was the last "real" color? Or was it the "clear Gray" at 8 since there was no change after that? I am following the Jack Keller Reciepe, except with sg of 1.082. 3 gallons of must.

Thanks for your help in advance.
Craig




 
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Old 09-01-2011, 03:13 PM   #2
crj5000
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Mar 2011
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Can anyone help me? If anyone knows that I did something wrong for the test please let me know.

Thanks



 
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Old 09-01-2011, 03:49 PM   #3
rniles
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Oct 2009
Whidbey Island, WA
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From what I understand the reading you take is when the solution first changes color and stays that color when swirled into the solution ...I thought this site helpful... http://www.grapestompers.com/article...re_acidity.htm ...which says for a white wine, it's supposed to change to pink ...a red wine usually changes to gray. I'm hoping someone else chimes in.
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Old 09-01-2011, 04:00 PM   #4
dmcoates
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Nov 2010
Wasilla, Alaska
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I am not really sure on this test, but I am a Drilling Fluids Engineer and titrate chemical tests for a living. On most titrating tests the end point will be when you see no more color change. I do a number of tests everyday and the colors that the test says you will see is not always what you do see. The color of the fluid testing pays a huge factor. All you are doing with this test is raising the PH t/ 8.2; Pheno will turn red in a clear liquid with a PH over 8.2. SO I would call your endpoint when we see no more change

Also you can add more that 3 drops, its just an Indicator, try 6 drops to make the color more predominate.

 
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Old 09-01-2011, 07:03 PM   #5
rniles
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Oct 2009
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Quote:
Originally Posted by dmcoates View Post

Also you can add more that 3 drops, its just an Indicator, try 6 drops to make the color more predominate.
Oh! ...didn't know that ...that's superb!
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Old 09-02-2011, 12:59 AM   #6
crj5000
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Mar 2011
Orlando, Florida
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Thanks for your help, I will try adding more phenol after fermention. I just racked it into a secondary today. So you believe that the "clear" gray is the last color change, so that is where my TA is?



 
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