Study on dealcoholized wine and valorization of by-products: a multidisciplinary perspective from processing and sensory science

The demand for partially dealcoholized (PDW) and fully dealcoholized (DW) wines have surged, driven by health considerations, social norms, and shifting personal preferences. The EU and OIV define “dealcoholized” wines as those with ≤0.5% v/v alcohol and “partially dealcoholized” wines as those with >0.5% v/v but below the minimum strength of their category before dealcoholization. This thesis validates and optimizes post-fermentation dealcoholization techniques to produce PDW and DW. Membrane (nanofiltration (NF), reverse osmosis (RO), osmotic distillation (OD)) and thermal-based (vacuum distillation (VD)) techniques were evaluated. Membrane evaluations showed NF had higher flux than RO, while RO-SG best retained key volatiles. Diafiltration produced PDW and DW but was constrained by legal restrictions on water addition. OD produced DW, correlating with volatile loss. A developed hybrid NF-OD system produced DW with stable color and acceptable sensory scores, despite reduced aromas. Dialysis produced poor quality DW. VD efficiently produced PDW and DW across wine types, though it showed higher color change and caused significant aroma loss. All tested methods successfully produced wines within regulatory alcohol limits. Storage stability was assessed through browning and oxidation kinetics. In model and real wines, ethanol concentration negatively correlated with browning rates. Phenolic degradation during storage followed zero-order kinetics and was strongly linked to declining antioxidant capacity. Oxygen consumption followed first-order kinetics and correlated with sulfur dioxide and phenol levels. Consumer studies revealed that over 76% of participants could differentiate wines by alcohol content, assigning DW the lowest quality scores. Primary motivations for consumption were safety, health benefits, and avoiding alcohol, while sensory shortcomings were the major barrier. Demographic factors influenced specific motivations. Finally, recovered ethanol was successfully valorised into a quality gin, dominated by terpenes and higher alcohols, which achieved high sensory acceptability. This work bridges technical, stability, and consumer-perception gaps essential to the dealcoholized wine sector.