## 6 Influence of Ageing Factors on the Coumarin Contents of Spirit Beverages
### Wood
[22] analysed nine commercial whiskkeys aged in oak wood, including four Bourbon whiskeys, and quantified scopoletin, umbelliferone, aesculetin, 4-methylumbelliferone and fraxetin, but their contents were not disclosed. Information on coumarin contents in rum according to the wood used is scarce. [PERSON] et al. [22] analysed three commercial runs, reporting an average scopoletin content of 1500 \(\upmu\)g/L. However, there is more substantial information about cachaca. Several studies were performed on cachaca, including wood from oak species and from species grown in Brazil (Table 7). Notwithstanding, it should be emphasised that some of the native species included in these studies do not correspond to the kinds of wood investigated (Table 1), and most of the experimental designs/available information do not allow a relationship to be established between the kind of wood used and the coumarin contents found in this spirit beverage. [PERSON] et al. [44] assessed the chemical composition of cachaca aged for 12 months in used barrels (200 L) made of European oak and new barrels (20 L) from four exotic kinds of wood. Results obtained after 12 months (Table 7) revealed very low contents of coumarins in the aged cachaca, and only the amburana and balsamo barrels released coumarins (quantifiable concentrations) into the distillite; the former was richer in these compounds, presenting a higher level of coumarin than 4-methylumbelliferone. However, these outcomes are not comparable, due to the different ageing conditions used in those essays: barrel usage and barrel size. According to the literature, the pool of wood-extractable compounds of used barrels is substantially lower than that of new barrels [195], which is the reason why oak barrels did not exert the expected effect. On the other hand, 20 L barrels have quite a higher surface-to-volume ratio than 200 L barrels, promoting greater extraction of wood compounds as well as favouring other phenomena occurring during ageing [196]. [PERSON] et al. [29] reported their results as percentage of peak area of coumarin in cachaca aged for 12 months in amburana (_Amburana cearensis_ (Allemao) A.C.Sm. ), castanheira (_Bertholletia excelsa_ Humboldt & Bonpland) and cabreiva (_Myrocarpus fondosus_ Allem.) 220 L toasted barrels: 19.08%, 0.51%, and not detected, respectively. It was the same for hydrocoumarin in cachaca aged in these kinds of barrels: 8.08%, 0.69% and 0.55%, respectively. The ageing in amburana barrels imparted the highest contents of coumarins, while castanheira conferred intermediate levels, and cabreiva induced the lowest ones, which contradicts the results obtained by [PERSON] et al. [43] for the wood of the cabreiva and castanheira species (Table 1). This discrepancy may derive from the wood variability and the different analytical methods applied. Finally, despite [PERSON] et al. [197] and [PERSON] et al. [25] analysing many cachaca samples from the market and from local producers, and presenting concentration levels of two coumarins (scopoletin and coumarin), the relationship with the kinds of wood used in their ageing was not revealed. In addition, [PERSON] et al. (2018) studied cachaca aged in 200 L oak barrels (unidentified species) for 12 months, and found that the levels of coumarin and 4-methylumbelliferone were lower than the limit of detection of the method. To the best of our knowledge, no information is available in the literature on the coumarin contents of grape marc spirit depending on the type of wood used for its ageing.