The answer makes no sense as it is formulated. The juice can be concentrated by ventilation, by vacuum or by heating, in all these cases if there is any essential oil in the juice it would evaporate in the process and would not at all come to the surface. If instead it is recuperated together with the evaporated water as water soluble molecules like in orange flower or rose water distillation, then it could be separated as is done to obtain absolute of orange flower water or of rose water, but it would be an absolute and not an essential oil.
The answer does not convince me at all.

AbdesSalaam Attar
Compositore Profumiere