A bit OT - Frozen apple juice

I'd suspect it is soluble substances (sugars, malic acid) which are in sufficient concentration to depress freezing point below the temperature of your freezer.

Of course, if you were a bit slow in collecting, pressing and freezing, it could contain some ethanol...

Isn't that known as apple-jack - alcohol concentrated by the freezing process?

Terry Fields

Of course wild fermentation can produce other alchohols as well. Methanol is not good for you. This is why people distill to get the pure fraction. And why bathtub gin can be lethal if not carefully distilled.

But whatever it is it is unlikely to be harmful. It will brew out if you are just making cider. You could have turned the applwes into mulch in a fridge if you had cooled thme sufficiently, put them in the freezer to freeze and then let the liquor drain off or filter out.

I suspect it is liquid that started brewing and will contain almost no fusel oil.

Distilling it with heat, the booze maker returns the first run to the brew and only uses the secondary condensate for making hooch.

Whiskyjack is named from the voyageurs who made it from well brewed cider and other base products. That could have enough fusel to hurt.