Doussot Franck, De Jéso Bernard, Quideau Stéphane, Pardon Patrick
Institut du Pin, Université Bordeaux 1, 351 cours de la Libération, 33405 Talence Cedex, France.
J Agric Food Chem. 2002 Oct 9;50(21):5955-61. doi: 10.1021/jf020494e.
The chemical composition of cooperage oak wood is highly variable, depending upon the tree species (Quercus robur L. versus Quercus petraea Liebl.), its geographic location, and the single-tree effect. In the process of cask-making, natural seasoning and toasting contribute strongly to the modification of the oak wood chemical composition and therefore influence wine cooperaging. HPLC and GC quantification of ellagitannins and volatile compounds such as whiskey-lactones, eugenol, and vanillin over a sample set of 61 pedunculate oaks and 72 sessile oaks originating from six different forests showed that natural drying leads to a decrease of the ellagitannins and total extractives content level and a quasi constant level of the volatile compounds. Toasting (medium type) drastically enhanced the loss of ellagitannins and the gain in volatile compounds. Statistical treatment showed that the species effect remained significant throughout the process of drying and toasting, but not the provenance. The poor correlation with ring width of extractives levels measured on fresh timber remained unchanged as did the single-tree effect, with high variability found for all chemical parameters. These results provide further evidence that cooperage oak selection should not be based solely on the wood grain or the provenance but rather on a species-provenance combination.
制桶用橡木的化学成分高度可变，这取决于树种（欧洲栎与无梗花栎）、地理位置以及单株效应。在制桶过程中，自然风干和烘烤对橡木化学成分的改变有很大影响，进而影响葡萄酒酿造。对来自六个不同森林的61棵欧洲栓皮栎和72棵无梗花栎样本进行高效液相色谱（HPLC）和气相色谱（GC）分析，以定量测定鞣花单宁以及挥发性化合物（如威士忌内酯、丁香酚和香草醛），结果表明自然干燥会导致鞣花单宁和总提取物含量水平下降，而挥发性化合物含量基本保持不变。烘烤（中等程度）极大地加剧了鞣花单宁的损失和挥发性化合物的增加。统计分析表明，在整个干燥和烘烤过程中，树种效应始终显著，而产地效应则不然。新鲜木材上测得的提取物水平与年轮宽度之间的低相关性以及单株效应保持不变，所有化学参数都存在很大变异性。这些结果进一步证明，制桶用橡木的选择不应仅基于木材纹理或产地，而应基于树种 - 产地组合。
