Acidity in supermarket juice wines

[Abervin]

What level of Total Acidity should I expect to see in say wine No1 before fermentation, if I were to dust off my Ritchies testing kit?

[lockwood1956]

You are measuring "Titratable" acidity not total acidity with the test kit (point of order Mr chairman ) would be in the order of 6g/l (or ppt for they are the same) to 7g/l expressed as tartaric acid but can be ok up to 7g/l (for conversion to expressed as sulphuric acid see tutorial for conversion chart

regards
Bob

[lockwood1956]

see here

http://www.winesathome.co.uk/forum/showthread.php?886-Testing-for-Acid-content

[lockwood1956]

Conversion chart here (scroll to page 2)

http://www.winesathome.co.uk/forum/showthread.php?886-Testing-for-Acid-content

[scouse]

I find my Wine #1 wines start off with a titratable acidity of around 2.7 ppt (sulphuric) before fermentation starts, and rise to around 4 ppt (sulphuric) post fermentation,
measured using the Ritchies Kit. I have seen similar increases with other recipes.

I have looked, but not found an explanation for this increase in acidity caused by fermentation - does anyone else know?

Steve

[Abervin]

You are measuring "Titratable" acidity not total acidity with the test kit (point of order Mr chairman )

Thanks for clearing that up, seems to depend on which book you look at One book calls it total titratable acid

So this morning I started a 15l Pinot Grigio style juice wine, measured the TA as 2.5ppt sulphuric (3.8ppt tartaric) added 10g Tartaric acid checked it again at 3.1ppt sulphuric (4.7ppt tartaric) raising it more than expected.

Will this be enough or should I add more to bring it to the 6ppt tartaric level?

p.s Having read Scouse's post maybe I should leave it as is if the TA rises during fermentation (or could that be dissolved Co2 skewing the test?)

pps. I tried tasting it and it just seams very sweet to me with no hint of acidity.

[scouse]

I always test after degassing, so I doubt it is dissolved CO2.

Prior to fermentation, the sweetness masks the acidity, so it is hard to tell by taste what it will be like. Nowadays, I prefer to adjust post fermentation, so long
as it is in the right ballpark at the start.

Steve

[SleepyDave]

I have looked, but not found an explanation for this increase in acidity caused by fermentation - does anyone else know?
Steve

Just came across this in Gerry Fowles 'Must':

"....fermentation of a fruit must by a quality wine yeast usually results in an overall acid increase....."

He gives no explantion why this happens but he estimates it at 15% and even more in high alcohol wines but says it may be cancelled out by precipitation where the acid is predominately tartaric.

[fatbloke]

Hum ?

Nothing to do with fruit per se, but I'm thinking that when meads ferment, the acidity of the sugars, which is masked by the sweetness and hence isn't apparent when the honey or must is tasted pre-ferment, what the acids actually are, I don't know but part of the reaction of fermentation produces stuff like gluconic acid and I'd guess that while the sugars are converting, some of the resulting acid(s) produced stay as acid.

Honey is 80% or more sugars, so if sugar and the sugars in the fruit are considered vice honey, then the r3action would be similar/the same, which logically, would increase the acid level.

As I say, not directly connected but the parallels can't be ignored. Just that honey must doesn't have the natural buffers that fruit/juice etc have naturally, which shows with the more considerable pH swings that can be observed in honey must/mead ferments......

Hopefully that makes sense (it does to me.....I think).

[scouse]

Hi fatbloke,

I have also read that honey fermentation can undergo large pH swings, so I took some measurements with the last batch that I made.
I have a pH meter (cheap Chinese import) and a Ritchies TA kit.

Recipe was 1362g honey in 4000ml (towards the end of fermentation I topped up to 4800ml and I added juice and zest of 1 orange; 1 cinamon stick and 1 clove, ie it is a modified JAOM )

Initial measurement : pH=5.9, TA=0.5 (sulphuric)

After 2 days: pH=2.6, TA=2.4;
I added 1ml Potassium Carbonate (Rictchies) to increase the pH in order to reduce stress on the yeast. This resulted in pH=3.1

Once fermentation was complete, I tested TA=2.4.
I added 7.5gm tartaric acid to increase to 3.5 (estimated)


As you can tell, I am a fan of taking measurements!

Steve

[fatbloke]

Hi fatbloke,

I have also read that honey fermentation can undergo large pH swings, so I took some measurements with the last batch that I made.
I have a pH meter (cheap Chinese import) and a Ritchies TA kit.

Recipe was 1362g honey in 4000ml (towards the end of fermentation I topped up to 4800ml and I added juice and zest of 1 orange; 1 cinamon stick and 1 clove, ie it is a modified JAOM )

Initial measurement : pH=5.9, TA=0.5 (sulphuric)

After 2 days: pH=2.6, TA=2.4;
I added 1ml Potassium Carbonate (Rictchies) to increase the pH in order to reduce stress on the yeast. This resulted in pH=3.1

Once fermentation was complete, I tested TA=2.4.
I added 7.5gm tartaric acid to increase to 3.5 (estimated)


As you can tell, I am a fan of taking measurements!

Steve

Yet, it's a bit weird IMO.

Of course, traditionals have little pH buffering to prevent the swings and there's also the point that both the alcohol, gluconic acid and other stuff can skew a TA result. It's why I tend not to add any acids up front, as they seem to just make the pH swings worse in the short term and then just add some later on, just too taste, not to try and make a mead just another "wine" clone, just to make it seem more "rounded".

It's also probably linked that while a juice wine type recipe doesn't experience the same levels of change that meads might, but there's still sugars that get modified, and hence it probably also suggests that it's best to just modify a taste with acids at the end of the making process. Of course, it's up to you whether you mod to a certain level to mimick a known wine type, or whether you just add a bit to make it more "rounded" to use the term again and more enjoyable to your own taste.

[Abervin]

I had read somewhere that its best to add acid at the start of fermentation as they don't intergrate as well when added later on, is this true?

[lockwood1956]

No, Adding acid after fermentation works ok

But like in cooking i always like to get everything right before it goes in the oven

I have experimented with side by side batches of wine and mead.....one acidity right before fermentation and the other where it was adjusted afterwards, no discernable difference was noted.

regards
bob

[Abervin]

But like in cooking i always like to get everything right before it goes in the oven

Do you always try to hit the 6 to 7g/l tartaric level with wine no1? and do you cold stabalise before bottling?

thanks
Adam

[lockwood1956]

I never do anything other than add 1 tsp cirtic acid to wine no 1

I dont cold stabilise wine No 1 either, 1 tsp citric acid seems to work out right every time, and cold stabilisation is for wines that have too much acidity, or to make them stable for longer term storage

it is designed to be made and drunk quickly, so these things are never a concern for me