Improvement of red wine quality through partial grape drying on the trellis: essay on the grapevine variety Diolinoir in Ticino

An essay of partial grape drying on the vine, with pruning of the fruit branch some fifteen days before harvest, was made on the cultivar Diolinoir in the Agroscope research vineyard in Gudo (TI), from 2006 to 2010. Sugar content was improved with the technique of grape drying on the vine. The total acidity and the malic acid of the must were also higher in the dried grape. This drying technique was however linked to yield loss of 27 % in average. The polyphenols index, the anthocyanin as well as the wine color intensity were higher in the dried grape treatments. At testing, the wines resulting from the dried grape were systematically preferred to those issued from the control. The main differences were noticed in the structure, the intensity and the quality of the tannins.