Experiment 1 - Acidity analysis

TA

If you want to analyze your wine for total acids concentration, you can now. I will show you how to do it. Please just keep in mind that the results might not be so accurate - however, it is fun to do some DIY lab experiments to know what is in your wine.

You will need sodium hydroxide (molarity 0.1N), phenolphthalein (1%), and pH litmus papers (1-10 scale). Prepare 5ml of wine sample in seethrough glass/cup/test-tube and add 3 drops of phenolphthalein. Get the NaOH into 5 ml syringe and drop by drop drip the solution to the sample (wine with phenolphthalein). At the same time, do round movement/shake gently with the sample - keep stirring up. Drip NaOH as long as the color indication keeps disappearing. Once the sample stays colored, count the ml of titrated NaOH and use the number for calculation formula:

TA = 75 x NaOH molarity x (NaOH titrated ml / Wine sample ml)

Example:

TA = 75 x 0.1 x (4ml/5ml)
TA = 6 g/l
   - The optimal TA should be somewhere between 6-9 g/l

Here is the link to detailed description: https://must-diywine.blogspot.cz/p/blog-page.html


VA
You can also try to test your wine for volatile acids - vinegar spoilage. This is a bit more complicated process where steam distillation is required. You can do the test for acetic acid concentration twice - right after the fermentation and then after storing (2 weeks and later). However, the biggest probability of wine spoilage is just during the process of storing.

You will need sodium hydroxide (0.1N), phenolphthalein (1%), and hydrogen peroxide 0.3%. Prepare 10-15 ml of wine and add 1-2 drops of hydrogen peroxide. Distill the solution (it will take cca 15-30 min). After take 10 ml of the distill and repeat the titration process above. Add 3 drops of phenolphthalein. Get the NaOH into 5 ml syringe and drop by drop drip the solution to the sample (wine with phenolphthalein). At the same time, do round movement/shake gently with the sample - keep stirring up. Drip NaOH as long as the color indication keeps disappearing. Once the sample stays colored, count the ml of titrated NaOH and use the number for calculation formula:

VA = titrated NaOH x 0.6 (if NaOH molarity is 0.1N and if the sample of distill is 10ml)
or
VA= (titrated NaOH x NaOH molarity) x 0.06 x (1000 / sample of distill ml)

Example:

VA = 1ml x 0.6
VA= 0.6 g/l
or
VA= (1 x 0.1) x 0.06 x (1000 / 10ml)
VA= 0.6 g/l

   - The optimal VA during fermentation is 0.2-0.4 g/l and later after storing between 0.6-0.9 g/l - if the values are higher, you can use it as vinegar for a salad :)

Here is the link to detailed description: https://must-diywine.blogspot.cz/p/blog-page.html