Simple Measurement of Titratable Acidity in Juice or Wine

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This is a simple and cheap way to measure TA in grape juice or wine samples. The following items are needed:
Erlenmeyer flask
Volumetric Burette to titrate the NaOH
Volumetric pipette to measure out 5 mL of the sample
Deionized water
Phenolphthalein Solution 1% (2 drops per sample).
0.1N NaOH solution (0.1M is the same deal)
5.0 mL of juice or wine

Опубликовано:

18 сен 2024

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Комментарии : 6

@jjj_anaa4533 Год назад

hi uhm where did you get the 1.5 when you multiplied the difference between the initial and final volume, where did you get the 1.5?

@geetanjalipansare8455 10 месяцев назад

Why we multiply it by 1.5

@johnmarold7787 2 месяца назад

Quick question. You started the test with 10.5 ml and ended with 21.2 ml. Shouldn’t the numbers decrease as you slowly drip the sodium hydroxide?

@markspc1 Год назад

There is some confusion about TA, does it stands for Total Acidity or Titratable Acidity ? Also I notice that you diluted your sample with water, wouldn't that change the concentration of the acid that you are measuring? And another comment: all videos that I have seem about measuring TA are about white grapes and the way you can tell that you reached 8.2 pH is when it turns pink. How would you do that if you have red grape juice. Thank you.

@insidewinemaking3264 Год назад

Hi Mark, TA stands for Titratable Acidity. Total Acidity would include the volatile acids such as acetic acid, and there is no single analytical measurement for total acidity. The water (which needs to be de-ionized) does not change the measurement, because the reaction of adding base to consume the acid up to pH 8.2 is independent of your sample concentration. It is important to control the volume of wine in the sample (5.0 mL in this video). There are a fixed number of acids, mostly tartaric and malic, that are reacting with the base. Adding water to the sample does not change that absolute quantity of titratable acid molecules. Red wine works, but it is more difficult to see the color change. It turns to a darker gray color and it is often helpful to have a light source down near the flask to be able to see that change. Good luck, Jim