that microbes can “spoil” fruit juice and gruel into something both delicious and pleasantly inebriating A few centuries ago, winemakers and distillers discovered another remarkable piece of good luck: simply storing wine, spirits, and vinegars in wood barrels turns out to give them a new and complementary dimension of flavor Oak and Its Qualities Though chestnut and cedar have been used in Europe and redwood in the United States, most barrels for aging wines and spirits are made from oak Oak heartwood, the older inner wood, is a mass of dead cells that supports the outer living layers The heartwood cells are filled with compounds that deter boring insects These are mainly tannins, but they include such aromatic compounds as clove-like eugenol, vanilla-like vanillin, and oaky “oak lactones,” relatives of the characteristic aromatics of coconut and peach From 90 to 95% of the heartwood solids are cell-wall molecules, cellulose, hemicellulose, and lignin These are mostly insoluble, but the lignins can be partly broken down and extracted by strong alcohol, and all can be transformed into new aromatic molecules when the wood is heated during barrel making (p 449) Coopers rely mainly on two European oak species (Quercus robur and Q sessilis), and ten North American species, the most important being the white oak (Q alba) The European species are mostly made into wine barrels, American oak into barrels for aging distilled spirits American oak tends to have lower levels of extractable tannins and higher levels of the oak lactones and vanillin Making Barrels: Forming and Cooking In order to make barrels, the cooper splits the heartwood into pieces, dries them, and forms them into thin, elongated staves, which are then roughly hooped together and heated to ... lower levels of extractable tannins and higher levels of the oak lactones and vanillin Making Barrels: Forming and Cooking In order to make barrels, the cooper splits the heartwood into pieces, dries them,... barrel making (p 449) Coopers rely mainly on two European oak species (Quercus robur and Q sessilis), and ten North American species, the most important being the white oak (Q alba) The European species are mostly made into wine... cellulose, hemicellulose, and lignin These are mostly insoluble, but the lignins can be partly broken down and extracted by strong alcohol, and all can be transformed into new aromatic molecules when the wood