Appassimento is a process of making wines, the most famous result of these is Amarone della Valpolicella originating in the hills of Verona in Italy's region of Veneto. The word comes from the Italian verb 'appassire' - to wither.
During this process the grapes are dried after harvest in the winery until they reach a point of desired concentration. The grapes can lose around 30% of their original weight, concentrating the sugars, flavour compounds, and acidity. Wines made by this process have augmented alcohol and/or sweetness due to the loss of water.
For Amarone and its sweet counterpart Recioto, the time of pressing of the grapes is dictated by the Valpolicella consortium so that a minimum desired level of concentration is achieved. The process sometimes attracts the benevolent fungus noble rot (botrytis cinerea), which adds an extra dimension to the aromatics and further concentrates the grapes. In other parts of Italy, and elsewhere in the world, the regulations are not so rigid.
The process is often confused with Ripasso, which although is another winemaking method, it is dependent on having dried grapes for the refermentation to occur. However, certain wines can be made by both processes as the Valpolicella Classico Superiore and Giuseppe Quintarelli from Giuseppe Quintarelli