i have a six gallon batch of wine i just started.i am using an acid titration kit.tested a sample today ,had to add 7cc of the sodium hydroxide to the sample. this is where im confused, what is the acidity of my wine and how much acid blend do i add to the must if any?(added 5 teaspoons from the start)
acid question
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A lot depends on your kit, strength of the sodium hydroxide, and how old the sodium hydroxide is.
I have a Crosby & Baker Wine Acid Test Kit. If you followed the instructions in that kit you would multiply 7cc * .25 = 1.75% Tartaricwhich is about 3 times what you want it to be. You are shooting for around 0.6% Tartaric.
Like i said this is for the Crosby & Baker kit, not sure which one you are using. One factor that can greatly affect the outcome of the test is the age of the sodium hydroxide. You need to keep a pretty fresh bottle around. I think it is only at full strength for 3 - 4 months.
I have a Crosby & Baker Wine Acid Test Kit. If you followed the instructions in that kit you would multiply 7cc * .25 = 1.75% Tartaricwhich is about 3 times what you want it to be. You are shooting for around 0.6% Tartaric.
Like i said this is for the Crosby & Baker kit, not sure which one you are using. One factor that can greatly affect the outcome of the test is the age of the sodium hydroxide. You need to keep a pretty fresh bottle around. I think it is only at full strength for 3 - 4 months.
geocorn
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LD uses a 1/5 normal while CB uses a 1/10 normal solution. I have been trying to determine the difference, but no one seems to have an answer. Maybe PeterZ will chime in on this thread. He seems to have chemistry down to an art form.
Anormal is one gram equivalent of solute (in this case sodium hydroxide) per liter of solution. So 1/10 normal is 1/10 of a gram equivalent per liter of solutionand 1/5 would be 1/5 of a gram equivalent per liter of solution.
The 1/5 N solution used by LD is twice as concentrated as the 1/10N used by C&B
So zigzag65 your wine's TA is .70% . What type of wine is it?
The 1/5 N solution used by LD is twice as concentrated as the 1/10N used by C&B
So zigzag65 your wine's TA is .70% . What type of wine is it?
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masta,
They came with the kit. It says to take the amount of sodium hydroxide added to obtain a color change and multiply by .25 to get acid content in percent tartaric.
The kit also includes Phenolphthalein (acid indicator solution) you add three or 4 drops to the sample prior to adding the sodium hydroxide. Maybe this is what makes it different.
They came with the kit. It says to take the amount of sodium hydroxide added to obtain a color change and multiply by .25 to get acid content in percent tartaric.
The kit also includes Phenolphthalein (acid indicator solution) you add three or 4 drops to the sample prior to adding the sodium hydroxide. Maybe this is what makes it different.
The volume of the sample used in testing must also be considered when determining the titratable acidity. You can use the following formula:<?
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TA = 75 * V * C/VS
Where:
V = volume of sodium hydroxide needed to reach the end-point
C = concentration of sodium hydroxide used (0.1 normal or 0.2 normal)
S = volume of the sample of wine or must
For example: you have a 15ml sample of wine and add 12ml of 0.1 normal sodium hydroxide solution to reach the end-point.
TA = 75 * 12 * (0.1 / 15)
TA = 6.0
The acidity of the sample is 6 grams per liter (6 parts per thousand or 0.60%).
amespace prefix = o ns = "urnchemas-microsoft-comfficeffice" />TA = 75 * V * C/VS
Where:
V = volume of sodium hydroxide needed to reach the end-point
C = concentration of sodium hydroxide used (0.1 normal or 0.2 normal)
S = volume of the sample of wine or must
For example: you have a 15ml sample of wine and add 12ml of 0.1 normal sodium hydroxide solution to reach the end-point.
TA = 75 * 12 * (0.1 / 15)
TA = 6.0
The acidity of the sample is 6 grams per liter (6 parts per thousand or 0.60%).
I think you will ok with it especially if you plan to back-sweeten. The addition of acid in the beginning as you did following a recipe is designed to get you to a specific target and the finial adjustment is better done with tasting it.
Joseph said:The volume of the sample used in testing must also be considered when determining the titratable acidity. You can use the following formula:<?
<O
TA = 75 * V * C/VS<O
<O
Where:<O
<O
V = volume of sodium hydroxide needed to reach the end-point
C = concentration of sodium hydroxide used (0.1 normal or 0.2 normal)<O
S = volume of the sample of wine or must<O
<O
For example: you have a 15ml sample of wine and add 12ml of 0.1 normal sodium hydroxide solution to reach the end-point.<O
<O
TA = 75 * 12 * (0.1 / 15)<O
TA = 6.0<O
<O
The acidity of the sample is 6 grams per liter (6 parts per thousand or 0.60%).<O
Thanks Joesph...the volume of the sample must be the reason why the calculation with the C&B kit didn't make sense.
PeterZ
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This is actually a more complex subject than it appears to us wine makers. There are several factors involved.
1) Concentration of the sodium hydroxide (NaOH). This can be expressed as "Normal (N)" or "Molar (M)". In the case of NaOH they are essentially the same, because NaOH is monovalent. 1 N NaOH is 40 g/L NaOH in water at 20C. (Don't worry about compensating for temperature - we don't need anything like that level of precision for winemaking. Who cares if your TA is 6.14330 g/L or 6.14820?)
2) "as" You can express acidity as anything - as HCl (hydrochloric acid), as H2SO4 (sulfuric acid), or in our case, as tartaric acid. The same sample will give you different numbers based on the "as" value.
The net result is that in the US we want a kit that expresses as tartaric acid, because those are the numbers we all use. After that, follow the equation in the kit, as they have worked out the math.
For the rest, g/L = parts per thousand. g/L x 0.1 = % (parts per hundred).
1) Concentration of the sodium hydroxide (NaOH). This can be expressed as "Normal (N)" or "Molar (M)". In the case of NaOH they are essentially the same, because NaOH is monovalent. 1 N NaOH is 40 g/L NaOH in water at 20C. (Don't worry about compensating for temperature - we don't need anything like that level of precision for winemaking. Who cares if your TA is 6.14330 g/L or 6.14820?)
2) "as" You can express acidity as anything - as HCl (hydrochloric acid), as H2SO4 (sulfuric acid), or in our case, as tartaric acid. The same sample will give you different numbers based on the "as" value.
The net result is that in the US we want a kit that expresses as tartaric acid, because those are the numbers we all use. After that, follow the equation in the kit, as they have worked out the math.
For the rest, g/L = parts per thousand. g/L x 0.1 = % (parts per hundred).
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