We want to made sweet low ABV cider. How to do that?
I understand that yeasts are dying somewhere between 10 and 15% ABV but we want our cider to be between 2 and 5% ABV. We can interrupt fermentation and bottle it when the desired ABV is achieved but how to convince yeasts to produce just right amount of bubbles and die afterwards?
"We want to made sweet low ABV cider" - Then you don't REALLY want to ferment straight apple juice. I would recommend making a "Graff", which is a low-ABV "malted cider". Basically its a cider that uses ale yeast and a small portion of malt extract to add some unfermentable sugars and to round out the flavor.
I've done it before and it was one of the most popular batches I've made. It does NOT taste like beer at all. It tastes like a sweet, rich cider. Furthermore, its ready within 6-7 weeks, (as opposed to 6-7 months for normal cider) and can be as low ABV as you want really (although I'd stick to about 5% to keep it from being 'thin').
Pasteurize your bottle product after you've added the sugar for sweetening. Place bottles in a 165F water bath for 20 minutes. That will inactivate any yeast in the bottle.
This will produce a still cider obviously.
If you want carbonation, you can experiment with opening a bottle every day until the carbonation is good. Then pasteurize as described above.
I use lactose, and I think it is one of the easiest solution. All natural sugar will be convert into alcool. And you will have sparkling cider by adding a little more sugar before bottling. Lactose will give a good taste (not like splenda). You can put 1kg of lactose for around 23L of cider.
The only problem is that lactose is not cheap (around 10$ for 1kg) and is hard to find (even in homebrew shops).
To get the bubbles you want, you'll probably have to rely on yeast attenuation. Get a low attenuating yeast so that it stops fermenting when there's still a decent amount of sugar left. When bottling, add some more sugar to wake them up and carbonate the bottles.
If you want more sweetness, use a non fermenting sugar like lactose or splenda. I use lactose in my hard lemonade which works out fine.