Tangible variation of sensory characteristics is often perceived in wine aged in similar barrels. This variation is mostly explained by differences in the wood chemical composition, and in the production of the barrels. Despite these facts, the literature concerning barrel-to-barrel variation and its effect on wine sensory and chemical characteristics is very scarce . In this study, the barrel-to-barrel variation in barrel-aged wines was examined in respect of the most important phenolic compounds of oenological interest and chromatic characteristics, considering both the effects of the (individual) barrel and cooperage. A red wine was aged in 49 new medium-toasted oak (Quercus petraea) barrels, from four cooperages, for 12 months. The resulting wines were evaluated for chromatic characteristics, anthocyanin-related parameters, total phenols, flavonoids and non-flavonoids phenols, flavanol monomers and oligomeric and polymeric proanthocyanidins . Principal Components Analysis (PCA) and variance analysis (ANOVA) were applied to investigate the relationships between barrels and to assess cooperage and individual barrel effect. Significant differences were observed for phenolic composition and chromatic characteristics in the wines aged in the different barrels, however without significant effect of the cooperage. The barrel-to-barrel variation of chemical parameters depended on
each specific parameter and was not uniform. Anthocyanin related parameters showed the highest variation, 25–37%, other phenolics varied 3– 8.5%, and with two exceptions, chromatic characteristics changed 1.7–3% . Cooperages were not shown to differentiate from each other in their internal variation, with relevance for practical application for most of the parameters analyzed in this trial, exception being made for pigments and especially anthocyanin related parameters . The relationship between the number of barrels and the expected variation for each analytical parameter was calculated, as reference for future measurements involving barrel lots, either in wine production or experimental design .
Authors: Pfahl Leonard1, Catarino Sofia1,2, Fontes Natacha3, Graça António3 and Ricardo-da-Silva Jorge1
1LEAF – Linking Landscape, Environment, Agriculture and Food Research Center, Instituto Superior de Agronomia, Universidade de Lisboa.
2CeFEMA—Center of Physics and Engineering of Advanced Materials, Instituto Superior Técnico, Universidade de Lisboa
3Sogrape Vinhos S.A.
*corresponding author: email@example.com
 Towey J.P., Waterhouse A.L. (1996). Barrel-to-barrel variation of volatile oak extractives in barrel-fermented Chardonnay. Am. J. Enol. Vitic., 47, 17–20.
 Sun B., Leandro C., Ricardo Da Silva, J.M., Spranger, I. (1998). Separation of grape and wine proanthocyanidins according to their degree of polymerization. J. Agric. Food Chem., 46, 1390–1396.
 Pfahl L., Catarino S., Fontes N., Graça A., Ricardo-da-Silva J. (2021). Effect of barrel-to-barrel variation on color and phenolic composition of a red wine. Foods, 10 (7), 1669. https://doi.org/10.3390/foods10071669
Keywords: Red wine, oak barrel aging, cooperage, barrel-to-barrel variation, phenolic composition