For store bought juice, just make sure there are no preservatives. Ascorbic acid is fine, nearly all store bought juice will have it. Basically, the acceptable ingredient list is apple juice, apple juice concentrate, water, and ascorbic acid. Don't buy juice with anything else added.
Everyone has their favourite yeast so a read of the sticky at the top of the page (CvilleKevin) should help (and confuse). My current "very favourite" is WLP775 (liqid yeast) but currently I can't get it here in Oz so my fallback is SO4 (dry yeast). I have also tried the "usual suspects" (Nottingham, EC1118, DV10, etc... they all work).
Bought juice can be quite sweet, which goes away during fermentation leaving not much else but acid and tartness, so my best results with bought juice are a base of "tart" juice (say, Granny Smith) plus a bit of sweeter juice (say Pink Lady). But, this all depends on what you can get. Ideally grind and press your own juice but sometimes this isn't practical.
So, read all the posts as they come up... there is a lot of good stuff in there. I mentioned in a recent post that when starting out, people are sometimes disappointed that their cider doesn't taste like a lot of the commercial alco-pop ciders. ( made with concentrate and water, yeast filtered out, sugar added, force carbonated). Most yeast will ferment down to 1.000 or below leaving a quite tart dry cider. I have found that SO4 will stop a bit above 1.000 so you get s some residual sweetness and flavour. Also, slow (time) and low (temperature) is the way to go... 6-12 months does wonders for cider. Adding a bit of sugar or juice then bottling gives a nice petillant mouth feel. So, experiment, experiment, experiment.
Spend $50-$60 on a hydrometer, Jolicoeur, and Lea and have fun.
I am new to the forum but have been fermenting cider for years. I have never had to add commercial yeast to get prompt fermentation started at room temperature. I bottle and refrigerate my cider after no more than 2 days at room temperature, or as soon as it shows signs of fermentation (froth, increased sediment, or firming/bulging of the plastic jug); if longer, the flavor suffers. I let it finish for at least 2 weeks in the fridge. I add no sugars or anything else. My cider is wonderfully sweet and fizzy (I live in upstate New York), and friends say no regional commercial ciders even come close. However, because I ferment in a closed container, usually with no secondary fermentation step, the alcohol content in my cider is probably pretty low (the sugar --> alcohol reaction never gets very far--the CO2 pressure stops it).
I got in the habit of slipping a tiny slice of unwashed, organic apple fresh from the orchard in each batch, knowing the apples had wild yeast on them.
UV pasteurization commonly does not kill all the wild yeast in the apple juice, however, and I also found that my fresh-pressed, UV-pasteurized (required in NY state if no preservatives) apple juice still turned into delicious cider even if it beat me to it and started bulging out of the plastic bottle before I got around to adding anything to it, bottling it, or refrigerating it.
• As above, buy no apple juice/cider with sulfites or other preservatives.
• You can start your cider 3 ways: depend on retained wild yeast in the juice as sold, add a bit of organic apple (the less sprayed in the orchard, the better), or use a commercial yeast (tons of these--see these forums), sold for beer-making, for wine or champagne, or specifically for apple cider.
• There are a bazillion ways to make cider on here and get the flavor/fizziness/density/ABV/sweetness you want. Just look around!
However, because I ferment in a closed container, usually with no secondary fermentation step, the alcohol content in my cider is probably pretty low (the sugar --> alcohol reaction never gets very far--the CO2 pressure stops it).
No, pressure doesn't stop fermentation, at least any pressure reasonably obtained by a home brewer. Fermentation can and will easily cause any sealed bottle you put it in to explode. Refrigeration, on the other hand, will slow fermentation to the point that it is effectively stopped, which is what you are doing. If you left a sealed container of what of your juices out at room temp, 100% chance it would explode, because fermentation would not stop with pressure. This is why fermentation is done with airlocks or pressure relief valves and not in sealed containers.
Have you ever actually measured your ABV? From your description of your process, I'd be surprised if it was more than 1 or 2%, if that.