Sweet and fortified wines produced from Aleatico grapes subjected to different dehydration process

In a study examining the impact of dehydration processes on wine quality, Aleatico grapes were harvested and exposed to two distinct dehydration methods, both utilizing identical air speeds. One batch underwent postharvest dehydration in a cold room (Cell) at 10°C, 60% relative humidity (RH), while the other batch underwent dehydration at room temperature (RT), ranging between 20 and 22°C, with a 40% of RH. Both dehydration tunnels worked with exhaust fans. The time to reach 35% weight loss was 37 days in cold room (Cell) and 19 days at room temperature (RT). After reaching 35% weight loss, grapes were pressed and divided in two lots: one was fortified to reach 16% alcohol content; the other lot partially fermented, and the fermentation was stopped with sulfur dioxide. The four wines resulting from the test are two passito (Sweet RT, Sweet Cell) and two fortified wines (Fortified RT, Fortified Cell) which have different characteristics. Analyzes of the phenolic composition and of the main oenological substances were carried out showing significant differences. Sweet wines had a higher concentration of alcohols and esters than fortified wines, higher concentrations of terpenes and ketones but lower aldehyde content. Sweet wines also had a higher concentration of organic acids but greater susceptibility to oxidation. Beyond that they presented higher phenolic fraction resulting chemically more uniform. Fortified wines, with high residual sugars and higher alcohol content, had less aroma but more aging potential, even if they were more tannic and with less elegance.