Aroma profile of oxidatively aged White and Tawny Port wines with different indication of age. Contribution of the non-rectified wine spirit

The aroma profiles of oxidatively aged White and Tawny Port wines with increasing indication of age were studied to understand differences in their ageing processes. Thirty-one and twenty-eight aroma compounds were quantified in Tawny and White Ports, respectively. Sotolon increased with age in both styles, contributing significantly to the aroma of older wines. Esters such as ethyl hexanoate, ethyl octanoate, and ethyl decanoate had odour activity values (OAVs) >1, especially in Tawny Ports, where their concentrations rose with age. In contrast, their levels declined in aged White Ports, reducing aromatic impact. 1,1,6-Trimethyl-1,2-dihydronaphthalene and β-damascenone also contributed to aroma due to their low odour thresholds. Differences in aroma evolution may be linked to differences in wine matrix composition. Wine spirit used for fortification influenced the initial aroma through its higher alcohols and esters. Over time, oxidation-derived compounds became dominant, enhancing aromatic complexity and differentiating styles. • Aroma evolution in White and Tawny Ports was studied throughout age indications. • Sotolon increases with age, enhancing aroma in both Port wine styles. • Key esters decrease in aged White Ports but increase in Tawny Ports. • Wine matrix affects aroma retention in Tawny and White Port wines. • Fortification and ageing volatiles together shape Port wine aroma.