I have brewed four or five batches of different frozen concentrates: apple, red grape juice, white grape, a pear combo, and freshly made apple cider as well. You get the idea.
I use London ESB 1968 for everything I brew; Brown Ales, Amber ales, porters, and stouts. This particular yeast strain has medium attenuation, with high flocculation .When I tried my first batch of frozen apple concentrate, added two or three teaspoons of the ESB yeast. It took off quickly, and I left it in primary for three weeks, cold crashed it, and racked it into another gallon bottle for another week. At that point It was slightly fizzy and not terribly dry either. I added some Splenda, put it in the fridge again, and it was quite obviously containing alcohol. I have done more than one batch of freeze concentrating and am quite impressed with the results. The water freezes, and makes the alcohol part slushy but still liquid with quite a bit more strong alcohol taste. If you freeze the concentrate more than twice, (for me anyway) you get some apple flavored paint remover. It does take a few days to concentrate the apple cider into apple jack. The easiest way freeze catch the now concentrated is to use a jug of some sort than be safely inverted. 3/4 fill it or so and after a day or two when the ice is solidly frozen, stand it upside down for a few minutes and the now high alcohol apple jack will collect in the neck of the bottle The first 2 or 3 ounces out of the ice block are well above 100 plus proof, so don't chug it...
