Volatile Organic Compounds in Sweet Passito Wines as Markers of Grape Dehydration/Withering/Drying Process

Twenty-four sweet Passito wines from Italy were analyzed through gas chromatography-mass spectrometry. Apart from the vinification process, which was unknown, the Passito wines differed in the water loss technique used, the grape variety, and the latitude/orography of provenance. Two volatile organic compound markers, ethyl acetate and furfural, were identified, characterizing wines produced with the technique of Vin Santo, wines from sun drying, and wines from late harvest. These compounds were found at low concentrations in wines produced with grapes dehydrated in “fruttaio” (closed facility), under controlled or uncontrolled conditions. Wines from Muscat varieties had more esters and terpenes, but the wines produced from grapes dehydrated in fruttaio in North Italy, particularly those grown on high mountains, had more than Muscat wines produced in South Italy or using sun drying. Primary and secondary aroma compounds are reported for each wine. A controlled environment during dehydration, preferably at low temperature, better preserves the aroma of grapes for wine production.