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

Abstract

Twenty-four sweet “Passito” wines from Italy were analyzed through GC-MS. “Passito” wines differed, beyond the vinification process which was unknown, by the water loss technique used, the variety, and the latitude/orography of provenience. Two VOCs (volatile organic compounds) markers, ethyl acetate and furfural, were identified, which characterized 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’ (close facility), under controlled or uncontrolled conditions. Wines from Muscat varieties had a higher content of esters and terpenes, but the wines produced from grapes dehydrated in ‘fruttaio’ in North Italy, particularly in high mountain, showed higher values than wines produced in South Italy and sun drying. Main and secondary aroma compounds are reported for each wine. It seems that a controlled environment, better if at low temperature, for the water loss process preserves the aroma of grapes for wine production.