Fortified or passito sweet wines from Aleatico grapes subjected to different dehydration conditions: chemical and aromatic profile using destructive and non-destructive analyses

Sweet or fortified wines hold significant cultural and economic value, particularly in regions where they are traditionally produced. Aleatico is a distinctive wine grape variety known for its unique aromatic characteristics, particularly used to produce sweet red wine. The drying technique significantly influences the wine's aroma and flavour profile. In the present study, the impact of different dehydration methods on Aleatico sweet and fortified wine quality was studied. Aleatico grapes were subjected to cold room (CR) dehydration (9 °C, 60 % RH) or room temperature (RT) dehydration (21 °C, 45 % RH) until 35 % of weight loss was reached. Dehydrated grapes were then fermented to obtain passito wines (Sweet RT, Sweet CR) or ethanol was added to the must to produce fortified wines (Fortified RT, Fortified CR). Non-destructive techniques (NIR-AOTF and E-nose) were applied for fast monitoring of wine differences together with chemical destructive analyses. At the end of the dehydration process significant increase in sugars and total extract was observed, without a significant difference between the two dehydration methods. Significant differences were observed in the time required to reach the fixed weight loss, with RT taking 19 days and CR only 47 days. Moreover, Sweet wines had a higher concentration of alcohols, esters, terpenes and ketones but lower aldehydes than Fortified wines. Sweet wines also had a higher concentration of organic acids but a greater susceptibility to oxidation, despite a higher and chemically more uniform phenolic fraction. E-nose and NIR-AOTF were able to discriminate between Sweet and Fortified wines. However, E-nose present evident limitations in discriminating between different dehydration conditions.