The distillation of Grappa is a complex art that revolves around marc, the still, and the Master Distiller. These three elements form the basis of the unique character and taste of each Grappa.
The first phase of distillation
The distillation process begins with filling the still boiler with fermented marc, followed by heating them. This initial phase allows the volatile substances like alcohol and part of the water to evaporate from the mass. Ethyl alcohol, the main substance composing a distillate, boils at 78.4°C, not at 100°C like water. However, since ethyl alcohol is in solution with water, the boiling point varies with its quantity compared to water. The more water present, the higher the boiling point.
Rectification Process
However, other volatile components are present in the marc to be distilled, which evaporate during heating and are transferred into the distilled liquid. Many of these substances are unpleasant and therefore unwanted, and they need to be removed. Fortunately, the various volatile substances found in the marc evaporate at different temperatures. Thus, by meticulously controlling the distillation process, it is possible to eliminate unwanted components while retaining all the quality substances.
The alcoholic vapors produced by heating the marc are subsequently concentrated, cooled, and brought to a liquid state, giving rise to the distilled product. In this second phase, the distillate is divided into three parts depending on its components and quality: the head, the heart, and the tail.
This process of separating the intermediate products of distillation is called rectification and aims to "purify" the distillate from unwanted volatile substances.