Beer Style: Common Cider (27A)
Recipe Type: other
Yield: 5 US gallons
Fermentation relies on infection by wild yeasts from the air. You could try this, but I wouldn't recommend it---there is no guarantee that a suitable wild yeast will fall from the heavens, and there will be plenty of other bugs waiting their chance to turn your apple juice into cider vinegar. Your best bet is to try to sanitize the apple juice in some way, and then add a starter of pure yeast.
This would turn out more like an apple wine, probably, and I would use a wine yeast if you can't get hold of any unpasteurized cider to culture from.
You may try crushing the apples yourself using a juice press. You may then try partly to sterilize in some way. Don't try to sterilize by heating: this imparts a cooked taste to the cider. You could try a very small quantity of sodium metabisulphite for a few hours (see recipes for wine-making from fruit). Pitch the yeast (and I would add some yeast nutrient) and ferment for about 2-4 weeks. This can be drunk immediately ("rough cider") or racked into secondary for up to 3 months. Don't worry about the clarity: it's unlikely to drop clear, due to all the pectins. If you're really confident about your sterilization, cider matures well in bottle.
One way of cutting down on contamination would be to boil a small quantity of the juice and make up a starter with the yeast - this large inoculum should compete out any unwanted strains, and the cooked taste from the small volume of starter won't be noticeable.
Source: Andy Phillips