An interesting question arrived at the website recently:
I was recently sent a catalogue of organic wines in which it said that organic producers grow grapes with thriving populations of wild yeast. Could you supply me with information explaining how one goes about acquiring or producing wild yeast for organic wines, ciders etc?
It's not difficult to do this, but I really would not recommend it...........you may waste your grapes, etc. unless you take great care. It is the method used by most commercial vineyards, where the yeasts have colonised whole areas over the centuries..
So....assuming you are able to work very cleanly............
Find some outdoor grapes or plums or sloes which are undiseased, and in tip-top condition. No flies, no wasps, nice and ripe, and no rotten fruit nearby. These fruit are covered in a fine "bloom". You'll see this if you touch the fruit; your fingermarks will be left on the skin. The "bloom" is actually wild yeast.
So.......make a wine with (or including) some of the fruit................4 lb fruit, 1 kilo sugar, 8 oz sultanas. Do not freeze the fruit; do not pour boiling water over it; assume it is clean (you've chosen it, after all) and get the fermentation going straight away. Put all the ingredients in a fermentation bin, stir it daily, and keep flies out. The fruit will come to the top after a few days; after about a ten days to a fortnight, when it starts to subside, take the grapes (or other fruit) OUT. If you leave them in the wine will go sour.
You have roughly a 90% chance of producing a good wine. It will take perhaps 7 days to start fermenting. Could be longer if the kitchen is cool. Stir it every day to discourage moulds. Do not add Campden tablets, etc, at any stage. This will kill wild yeasts. Start other batches by scooping out half a pint of the mixture and adding it to your next container which needs fermenting.
As long as you're scrupulously clean in your procedures, you can even use a small amount of nearly-finished wine, if you get that far, to start off a fermentation in the following year. This is what I do; though I do not use wild yeasts.
However, my father has used them, and he's found that if you're very clean and your initial source contains no acetic acid bacteria, there is no problem. You can even use the bloom off very clean indoor grapes. Wild yeasts are fine. The wine you get (he does elderflower, ginger and elderberry - just the three types) is indistinguishable from that which you get with commercial yeasts. Their alcohol tolerence is a bit lower than some of the specialist yeasts; around 12% as opposed to 15-16%.
Nigel Deacon / Diversity website
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