Influence of Oak Wood Seasoning Duration and Toasting Degree on Endogenous and Wood-Derived Compounds of Brandy Italiano

Abstract The Geographical Indication (GI) “ Brandy Italiano ” applies exclusively to brandy produced in Italy through the distillation of wine obtained from grapes cultivated and vinified within the national territory. Its product specification requires a minimum aging of six months in oak casks smaller than 1000 L to be marketable. During aging, the characteristics of the final product are affected by the different treatments applied to oak wood during the cooperage process. This study aimed to assess the impact of different oak wood toasting levels and natural seasoning durations on the whole volatile profile of this GI, including wood-derived compounds as well as varietal and fermentative volatiles. The research was conducted on brandies from Trebbiano Romagnolo wines distilled via two-step distillation and aged for 8 months in 350-L oak barrels. Cooperage woods were naturally seasoned for 24 or 36 months before being toasted under light or heavy conditions. The products were analysed via solid-phase extraction coupled with gas chromatography‒mass spectrometry to determine their overall volatile composition and via high-performance liquid chromatography with photodiode array and fluorescence detection to quantify wood-derived compounds. Heavy toasting significantly increased the content of most wood-derived aromatic compounds, particularly furan compounds and phenolics from lignin degradation, and induced the formation of 5-acetoxymethyl furfural, a potential marker of short-term aging in distillates from heavily toasted wood. Seasoning duration affected the levels of gallic and ellagic acids, as well as the ratio between cis - and trans -methyl-γ-octalactones. The wood treatments also influenced certain varietal and fermentation aromas, including terpenes and ethyl esters.