[Nelari]

Maple Cider Dubbel is an interesting recipe in Emma Christensen's book Brew Better Beer, p.134. Apple cider is a largish ingredient such that you take half the batch size of it (2.5 gallons of apple cider for a 5-gallon batch of beer, say) and reduce that by half (by boiling) before adding it to the main boil. Would anyone have an idea about the kind of apple cider that is needed? And why is it reduced? There is no alcohol in apple cider, right? Wouldn't that be called hard cider?

[KellerBrauer]

If I understand your questions, any apple juice/cider can be used to make hard cider.  You only need to make sure the product has been pasteurized to kill any yeast that may be present.  If it has not been pasteurized, boiling would surely serve that purpose.

As far as boiling after pasteurization, my guess is that by boiling and reducing the apple juice/cider, the sugars would get concentrated by evaporating off the water.  This would aid to a higher degree of alcohol when its fermented.  Once it’s fermented, it becomes “hard cider”.

[Nelari]

If I understand your questions, any apple juice/cider can be used to make hard cider.

Sorry; I seem not to have been clear enough. The Maple Cider Dubbel from the Christensen book is a recipe for beer. That is, the idea is not to make apple cider; it is to make beer using apple cider as an ingredient (the recipe also includes maple syrup as an ingredient).

The "Dubbel" is a reference to the Belgian Dubbel style of beer.