Red and Green grape juice

[Locky]

Bought some from asda at it was fairly cheap, 2 for £1.50.
The thing is it is 100% grape juice but not from concentrate, will these be ok to use in wines?
do they need boiling to rid of any preservatives or addys?
Cheers.

 

[tubby_shaw]

Great find :thumb: They will be great to use in wines :)
All the supermarket grape juices that I have used have been Pressed, "not from concentrate" :thumb:
The ingredients list on the carton should tell you if there are any preservatives in the juice, I think that the only preservative that is removed by boiling is sulphur dioxide (E220) :wha: can any one confirm or disprove this?

 

[leondz]

You want sulphur dioxide in there as the yeasties love it (in moderation) - it's one of the things that sodium metabisulphite (aka campden tab) usage introduces to the must.

 

[tubby_shaw]

You want sulphur dioxide in there as the yeasties love it (in moderation) - it's one of the things that sodium metabisulphite (aka campden tab) usage introduces to the must.

Really :shock:
I was always lead to believe that it was a major yeast inhibitor :wha:

We live and learn :)

 

[Locky]

Brilliant cheers!
Dont you just love science :wha: :hmm:

 

[Moley]

Bought some from asda at it was fairly cheap, 2 for £1.50.
The thing is it is 100% grape juice but not from concentrate, will these be ok to use in wines?
do they need boiling to rid of any preservatives or addys?

100% Pure Pressed Grape Juice or 100% Grape Juice (from concentrate) doesn't seem to make a blind bit of difference. What you get varies from shop to shop. I tend to get mine from Tesco, pure pressed, 3 litres for £2.

There shouldn't be any preservatives unless it's a cheapo grape juice “drink”, when it's probably mostly water.

 

[leondz]

You want sulphur dioxide in there as the yeasties love it (in moderation) - it's one of the things that sodium metabisulphite (aka campden tab) usage introduces to the must.

I was always lead to believe that it was a major yeast inhibitor :wha:

I can't remember where I read this, but, well, it obviously needs checking! :wha:

In high enough SO2 concentrations stuns everything, but at lower levels, just stuns non-alcohol producing yeasts (e.g. Sacc. cervisiae, our favourite) - http://www.cider.org.uk/sulphite.html.

SO2 also helps fend off microbes that contribute to oxidation - http://www.ajevonline.org/cgi/content/abstract/2/1/43.

With winemaking I usually use potassium sorbate (if anything) to stop the yeast producing, but it's less effective at alcohol concentrations below 10%, if I remember correctly. In fact, here's a reference - http://www.bcawa.ca/winemaking/sorbate.htm. In my experience you have to be a bit careful with this as too much affects with flavour.

If that's not enough, there's really technical information on SO2 on that BWACA site too, http://www.bcawa.ca/winemaking/so2use.htm. Pretty interesting stuff. There's probably a calculator or something that could be made out of all of that somewhere, not sure how useful it'd be if everyone's wines are turning out well enough though! :thumb:

 

[leondz]

Brilliant cheers!
Dont you just love science :wha: :hmm:

sorry for the deviation, hopefully there's wasn't too much hesitation or repetition

 

[tubby_shaw]

I can't remember where I read this, but, well, it obviously needs checking! :wha:

I wasn't trying to be "funny" with my post leondz, I too remember reading somewhere (CJJ Berry?) that campden tablets add something beneficial to the must :thumb:
I simply thought that the addition at the start was to inhibit any yeast but the one that was pitched (in sufficient quantities not to succumb to sulphites) :wha:

 

[leondz]

Not at all, I'm just trying to avoid talking nonsense! :thumb:

 

[tubby_shaw]

You were right in that the use of SO2 in the form of campden is beneficial leondz :thumb:
I found the source in First Steps In Winemaking by C.J.J. Berry :party: on page 111 of my copy he writes that "Regularly using a campden tablet per gallon in the "must" 24 hours before adding the yeast will also improve the wine by putting into it a little glycerine"