If picking botrytized grapes is painstaking, obtaining their juice and persuading it to ferment is at least as difficult because of its composition (see noble rot). pressing is a physically difficult operation, and, contrary to the usual practice, later pressings yield juice superior to the first pressing because it is richer in sugar and the chemical compounds produced by the botrytis fungus. The most dehydrated grapes in the press may not in any case yield juice until they have been pressed twice or three times.
