Help with testing for acid in muscadine must.

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crj5000

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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
 
Can anyone help me? If anyone knows that I did something wrong for the test please let me know.

Thanks
 
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.
 
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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