I recently fermented Kedem brand grape juice (which contains potassium metabisulfite) by only adding rouge red star yeast (and slapping on airlock and leaving it on my kitchen counter). I recently got into a discussion if there is any way to ferment it without adding any ingredients at all - stirring, refrigerating, leaving it outdoors, adding an airlock etc. would be allowed (this may have some applications to an esoteric aspect of Jewish law). Does anyone know if its possible or will the wine spoil first?

2 Answers 2


The chances of this working are about zero. It will eventually ferment, but the results will probably be bad. If you want to get yeast into the grape juice in a natural way, you can put a piece of fruit or berry into the grape juice. The best thing is to find some Organic grapes at your local grocery. I say Organic because there will be a better chance they have more robust yeast colonies on the skins than non organic. The "bloom" on the skins of the grapes is made up of many different yeasts and bacteria, but usually the best for making wine will survive.

I would put the grapes, minus the stems, in a blender for a little bit and then dump the whole mess into your grape juice. You should see fermentation within 24 hours. When the fermentation is done, you'll need to drink it quickly unless you put more sulfites in the "wine".

If you won't/can't put some fruit or grapes in there. Put it all in a big clean bucket outside on a nice sunny day with little or no wind. Preferably near some flowers or trees (you want the pollen to fall in there). Pollen contains a lot of yeast. You only need it outside for an hour or so. Then put it in a carboy or just cover and let it try and ferment. It might or might not work but this is how they make spontaneously fermented beer.

BTW, all the Metabisulfite in the juice will be blown off in the fermentation process so you will need more to keep it preserved afterwards.

  • Thanks. I'm not looking to make it ferment by adding anything. Adding anything would remove what I am trying to accomplish. If I wouldn't add anything would it be similar to Pruno, that it will ferment and be alcoholic (in the right environments) but it may be dangerous?
    – Eliyahu
    Commented Apr 13, 2018 at 19:31
  • It will never be dangerous, no more dangerous than wine. Might be vinegar or moldy, but it won't kill you. Not adding anything like a few grapes is a sure way to end up with crap. What's the harm in adding a couple of grapes to get it started in the right direction? Commented Apr 13, 2018 at 20:06
  • I don't see how that would break any Jewish dietary laws. But if you must, put it all in a big bucket outside on a nice sunny day with little or no wind. Preferably near some flowers or trees (you want the pollen to fall in there). You only need it outside for an hour or so. Then put it in a carboy or just cover and see what happens! Commented Apr 13, 2018 at 20:15
  • Thanks. If you edit that into your answer I'll accept it. It's actually not about Jewish dietary law. It's a side point relevant to this question judaism.stackexchange.com/q/91234/13482
    – Eliyahu
    Commented Apr 13, 2018 at 20:25
  • OK, I'll add it and I read your question on Judaism and it's not exactly true that if there are sulfites present in the grape juice it will not ferment. We routinely add sulfites to our grapes when we make wine. It's more for suppressing the wild unwanted yeasts/mold/bacteria and letting the ones through that we want because they have built up a tolerance to a certain level of sulfites. saccharomyces cerevisiae is one such critter. Commented Apr 13, 2018 at 20:54

It is possible it could work, but you have to be pretty lucky. The chance of getting some local acetobacter or wild yeast that could survive and spoil the wine would be high.

If you have a bunch of grapes and used them to prime your grape juice, that could be a better way than just stirring outside, as the yeasts on the grape skins are what was the fermentor historically.


  • Thanks. That's an awesome link by the way. I'm wondering, why would this be different than beer? Historically, beer was made without adding yeast and barley doesn't contain yeast naturally.
    – Eliyahu
    Commented Apr 13, 2018 at 19:33
  • 1
    Because over thousands of years people saved the yeast from one batch to the next unintentionally culturing strains of yeast (saccharomyces cerevisiae) that are the best at making beer or wine. Barley does have some yeast on it, just not much and you cook it anyways so that would kill any yeast... Commented Apr 13, 2018 at 20:09
  • People fermented beer and wine in wodden vats, and the yeast colonised the wood, thereby being saved between batches. When a vat or barrel went bad it would be retired from use and toasted or used for other purposes. Therefore the 'good' yeasts were maintained between batches and the 'bad' yeasts removed from circulation.
    – Mr_road
    Commented Apr 16, 2018 at 9:58

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