how do I test a wines acidity?

[Stanleythecat]

Hi All

If I want to hit a certain acidity at the beginning how do I go about testing it. I understand their are two measurements that can be used 'ph' and 'total acid', although I have no idea how best to get either; ph meter/titration kits... Why do they differ and do you need to do both?

Any help very gratefully appreciated.

Leo

 

[Stanleythecat]

Anyone?

Leo

 

[oldbloke]

I've never done it - I rely on existing recipes - and a conversation I once had about it confused me.
If CJJB has owt on it in The Book I'll pass on his wisdom asap

 

[Brewtrog]

I wouldn't bother with titration, it's an analytical method far over accurate for what you would need (and complicated). Taking a pH reading using something like litmus or UI paper would probably be all you really needed. Or that's what I'd imagine from my chemistry background (trust me you get sick of titrations). I've never known a recipe be particular enough for me to bother with either though to be perfectly honest.
p.s. both titration and litmus/UI will give you the pH anyway.

 

[evanvine]

If you are vinting a real wine from grapes (not an alcopop) then titration is essential!
Your "must" needs to be between 0.5 - 0.7% H2SO4.

 

[bobsbeer]

A reasonably good article can be found HERE. I usually test for ph as I find most wine tastes better in the 3.3-3.5 range, but it depends on what you are making. Titration tests are expensive and are testing for tartaric acid which is the main acid in grapes. You ideally want to keep your wine below 4 for preservation reasons, but that is fairly easily achieved. I add Tartaric acid if it needs increasing, but some add citric acid. I have found that even good kits can have a surprisingly low ph and adding tartaric acid has improved them once aged. At a guess manufacturers keep them lower so they taste better young. I have an electronic tester but you can get litmus papers from most HB shops.

 

[Stanleythecat]

Found this simplified explanation on another site that might help... helped me!

'pH is a measurement of the strength of acid, while TA is a measurement of the percent by weight of an acid. Different acids have different strengths. For example, lactic acid is not nearly as strong as sulfuric acid, so if you had two one-liter samples of water and dissolved 10 gms sulfuric in one and 10 gms lactic in the other, they would both have the same percent of acid by weight, but the one containing sulfuric would have a lower pH because it's a much stronger acid'

Leo

 

[Stanleythecat]

A reasonably good article can be found HERE. I usually test for ph as I find most wine tastes better in the 3.3-3.5 range, but it depends on what you are making. Titration tests are expensive and are testing for tartaric acid which is the main acid in grapes. You ideally want to keep your wine below 4 for preservation reasons, but that is fairly easily achieved. I add Tartaric acid if it needs increasing, but some add citric acid. I have found that even good kits can have a surprisingly low ph and adding tartaric acid has improved them once aged. At a guess manufacturers keep them lower so they taste better young. I have an electronic tester but you can get litmus papers from most HB shops.

Thanks Bob

 

[evanvine]

Found this simplified explanation on another site that might help... helped me!

'pH is a measurement of the strength of acid, while TA is a measurement of the percent by weight of an acid. Different acids have different strengths. For example, lactic acid is not nearly as strong as sulfuric acid, so if you had two one-liter samples of water and dissolved 10 gms sulfuric in one and 10 gms lactic in the other, they would both have the same percent of acid by weight, but the one containing sulfuric would have a lower pH because it's a much stronger acid'

Leo

% acid is % acid, no matter what type of acid!
I agree that you will need more of certain acids to get to the same acid %

If you have a litre of acid solution at say 0.6% and you dilute with another litre of neutral solution you will finish with a solution at 0.3%
One litre of acid at say ph4 and you dilute with another litre of neutral solution you will still have ph4!!

 

[oldbloke]

Titration tests are expensive

Kit costs under 6 quid, I imagine it has enough NaOH and phenolphthalein to do more than one batch. Seems unnecessarily complicated for my level of expertise, but as I'm a gadget nut....

 

[oldbloke]

I add Tartaric acid if it needs increasing

One advantage of tartaric is that an excess of it may crystalise out (found some "wine diamonds" in my nettle wine - the lad took them into school for show&tell!)
Also it's the main acid in grapes so may help that real-wine perception

 

[Brewtrog]

Seems unnecessarily complicated for my level of expertise

Trust me anyone who has gone through A level Chemistry will tell you that they're far too complicated and fiddly more to the point, . You can probably find a titration calc on the net, but I've never seen one, but then that might have just been because we had to show our workings. Considering all they do is give a very accurate pH reading (if done correctly [and well] with analytical reagents) so as far as I can see litmus paper, which is cheaper, easier and at the least just as obtainable seems to be a far more sensical manner of checking the pH of a must.

 

[tonyhibbett]

Understanding and controlling wine acidity is not required for most kits and 'tried and tested' recipes, but there is so much variation in the acidity of fresh fruit and veg, depending on variety, soil, weather and ripeness. I used to make some pretty sour wine from my grapes and apples but since I have been able to measure and adjust the acidity, they are vastly improved. It's a fascinating subject.The problem is that there are several different types of acid which may be present in wine, with different effects on the palate, and the simple titration kits, pH meters and litmus papers do not distinguish between them. Some recipes for acid deficient ingredients include the addition of citric acid, which is fine for a sweeter wine but not a dry one. Not many people would enjoy a glass of freshly squeezed lemon juice!