Grappa is aquavit obtained from the distillation of grape marc - this name can only be used if produced in Italy or in the Cantone Ticino (Switzerland).
Grape marc is what is left over from wine making, more specifically the skins and seeds of grapes.
White or young grappa retains the scents of the original vines and of fermentation, skillfully selected by the distiller.
Grappa matured in wood, resting in wooden barrels for a limited period of time, has a smoother character.
Aged grappa is matured in wooden barrels for a longer period of time, in order to acquire distinctive features, brought about by the quality of the wood and by the osmosis that occurs through its pores. Excessive ageing causes the grappa to lose its freshness sensation and the flavors of the vine selection.
It means that it is made by using the grape marc of a single variety of vines.
Each has a unique character and it can't be said that one is superior to the others.
There are no particular requirements and it can be stored for an indefinite period of time.
BATCH STILLS: The grape marc is placed in small steam boilers. The steam, injected from the bottom, goes through the grape marc removing its alcohol contents. The boilers must be filled up and unloaded one batch at a time and each batch is distilled under the careful supervision of the master distiller, who removes the initial and final parts of the distillate (the "heads" and "tails" that give an unpleasant taste to the product). CONTINUOUS: The grape marc travels continuously inside an apparatus call "disalcolatore", where it passes through a jet of steam coming from the opposite direction. This is an industrial method that produces a rather bland quality of grappa.
It is aquavitae obtained from fermented must (pressed grapes at fermenting stage).
It indicates the percentage of alcohol, for example 40%vol or 40° = 40 parts alcohol and 60 parts water.
The name "grappa" can only be used for aquavitae produced in Italy or in the Swiss Cantone Ticino from grapes coming exclusively from those areas.
For what concerns young grappa, the ideal temperature ranges from 9 and 13°C, for aged grappa it is around 17°C. When in doubt, colder is better.