Bourbon whisky

American whisky is produced from com, rye and wheat by means of saccharification with malt fermentation of the lauterized mash and through double distillation in column distilling units. The product is then stored in charred casks made from oak wood. Bourbon whisky contains at least 51% com distillate and grain whisky at least 80%. Rye whisky has a minimum content of 51% rye and wheat whisky contains mostly wheat distillate. 

The rye whiskies show a higher content of solids, acids, esters, etc., than do the Bourbon whiskies, but this is explained by the fact that heated warehouses are almost universally used for the maturing of rye whiskies, and unheated warehouses for the maturing of Bourbon whiskies. 

Table XIV.—Average, Maxima and Minima Data for Bourbon Whiskies. Calculated to ioo Proof. 

American Kentucky straight bourbon whisky, stored for at least 3 years in a charred oak cask. 

Poisson, L., Schieberle, P Characterization of the most odor-active compounds in Bourbon Whisky. J. Agric. Food Chem. (submitted)... 

For example, the main odour-active components of Bourbon whisky are aldehydes, the most important of which are 3-methylbutanal, 2-methylbutanal, 2-methylpropanal and (2 , 4 )-deca-2,4-dienal. Important components are also ethyl esters, such as butanoate, 2-methylpropanoate, (S)-2-methylbutanoate, 3-methylbutanoate, hexanoate and octanoate, and lactones, especially (3S,4S)-whisky lactone, 8-nonalactone and y-decalactone, some phenols (vaniUm and eugenol) and (E)-P-damascenone, which is a degradation product of carotenoids. 

Poisson L, Schieberle P. Characterization ofthe key aroma compounds in an American bourbon whisky by quantitative measurements, aroma... 

White oak barrels of 190 liters (50 U.S. gallons) that have been previously used for bourbon maturation are often used a second and third time to age Canadian whisky. This used cooperage along with the higher proof distillation gives Canadians their characteristic light flavor compared to the heavy flavor of most bourbons aged in new charred oak barrels. 

Aging practices differ somewhat. British custom is to store the whiskey in uncharred oak barrels while American whiskies, both Rye and Bourbon, are stored in charred barrels. The color and solids of whiskey aged in uncharred packages are much smaller in amount and more water soluble than those of whiskey stored in charred packages. The charring also results in a bead of oilier consistency and greater permanence than the uncharred barrel imparts. 

Note re American Whiskies.—All the above samples were retail, bottle goods, excepting Rye A, which was received from Dr. 1 ey. Both the Bourbon samples and Rye samples A, B, and C, are pot still whiskies, the others probably blends. 

The average composition of New and Old Bourbon, and New and Old Rye whiskies (American), based on a large number of analyses of samples examined in the laboratory of the Department of Agriculture, U.S.A., are given below. These analyses were kindly transmitted to me by Dr. Wiley, chief chemist of the Department. 

Ellagotannins occur as components of commercial tannic acid, various extracts and infusions (e.g. teas from medicinal herbs and bark of trees) and are also natural constituents of some alcoholic beverages matured in oak barrels, for example high quality wines and spirits, such as cognac, brandy, whisky, bourbon and rum. All components extracted from the wood are then degraded to some extent, which gives rise to various phenohc compounds that have a role to play in the flavour-active components of the alcohohc beverage (Table 8.44). 

Ralph, R. 1995. The production of American whiskies (bourbon, com, rye, wheat and Tennessee). Chapter 12 in The Alcohol Textbook. T.R Lyons, D.R. Kelsall, and J.E. Murtagh (eds.). Nottingham University Press, Nottingham, U.K. 

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