Congener Development in Bourbon Whisky Matured at Various Proofs for Twelve Years

Abstract

Abstract The color intensity and congener concentration of bourbon whiskies matured for 12 years decreased as the entry proof increased from 109 to 155°, except for fusel oil content which remained approximately constant. The average annual cumulative evaporation loss rates, in per cent of original proof gallons/year, were approximately the same at all 6 proofs, i.e., 3.0%/year or 3 6% for the 12 year period. The relative rates of formation of total barrel-derived material, a newly proposed parameter defined as the sum of the increase in volatiles and nonvolatiles in an aged product, were quite similar for comparable time intervals regardless of entry proof. There was greater variation among the relative rates of formation of individual congeners at the different entry proofs. Although all congeners except esters attained at least 5 0% of their ultimate (twelfth year) value during the first 4 years, it appears that appreciable congener development continues at least through 12 years. Esters developed linearly over the 12 year period.