Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: dgt20 on 23/02/2018 09:36:00

Title: How do winemakers measure their grapes/must pH level?
Post by: dgt20 on 23/02/2018 09:36:00
What method/procedure do winemakers perform to find the grape/must pH? What would be the steps/calculations?
Title: Re: How do winemakers measure their grapes/must pH level?
Post by: Colin2B on 23/02/2018 14:46:46
As an amature winemaker I used indicator papers or titration. For a different purpose I bought an electronic pH meter and i would have thought this is what professional makers use.
Title: Re: How do winemakers measure their grapes/must pH level?
Post by: dgt20 on 24/02/2018 02:02:43
As an amature winemaker I used indicator papers or titration. For a different purpose I bought an electronic pH meter and i would have thought this is what professional makers use.

What would be  the steps to fine pH through titration? What neutralizer and indicator would you use? Thanks!
Title: Re: How do winemakers measure their grapes/must pH level?
Post by: Bored chemist on 24/02/2018 11:19:37
You can't really use titration to measure pH, but you can use it to measure total acidity.
Ideally, you want to know bot the acidity and the pH.
However, if you are fermenting fruit juice you can rely on the fact that the yeast has had billions of years to evolve to deal with the typical range of pH/ acidity found in fruit.

If you wanted to ferment cola - which is rather more acidic than most fruit, you might want to raise the pH a bit.
Given that cola is quite dark you might not be able to see the colour change of pH paper properly.
A pH meter would be useful in that case.
But who would want to ferment cola?

Title: Re: How do winemakers measure their grapes/must pH level?
Post by: dgt20 on 24/02/2018 11:53:06
You can't really use titration to measure pH, but you can use it to measure total acidity.
Ideally, you want to know bot the acidity and the pH.
However, if you are fermenting fruit juice you can rely on the fact that the yeast has had billions of years to evolve to deal with the typical range of pH/ acidity found in fruit.

If you wanted to ferment cola - which is rather more acidic than most fruit, you might want to raise the pH a bit.
Given that cola is quite dark you might not be able to see the colour change of pH paper properly.
A pH meter would be useful in that case.
But who would want to ferment cola?

Im currently looking into finding titratbale acidity of wine, what is the difference between titrateable acidity and total acidity? Are the titration steps basically the same?
Title: Re: How do winemakers measure their grapes/must pH level?
Post by: Bored chemist on 24/02/2018 17:15:53
Tiratable acidity and free acidity are pretty much the same thing.
Title: Re: How do winemakers measure their grapes/must pH level?
Post by: Colin2B on 24/02/2018 18:09:26
You can't really use titration to measure pH, but you can use it to measure total acidity.
Sorry, my loose wording

However, if you are fermenting fruit juice you can rely on the fact that the yeast has had billions of years to evolve to deal with the typical range of pH/ acidity found in fruit.
For most fruits that works well. When i’ve adjusted acidity it’s been because much of the base has been low acidity eg bananas or honey. Bananas are often used to give body to a homebrew that could be fairly thin.