Bourbon and Rye Whiskeys Are Legally Distinct but Are Not Discriminated by Sensory Descriptive Analysis

Abstract

We present a Descriptive Analysis (DA) of a large representative sample (24 whiskeys) of two legally distinct types of American whiskeys: bourbon and rye whiskey (respectively distilled from a fermented “mashbill” of at least 51% corn or rye). We wanted to determine whether a trained panel could find sensory differences between these two products. We used standard DA: 11 judges were trained for 10 hours to develop a lexicon of 24 flavor, taste, and mouthfeel descriptors for the 24 whiskey samples (15 bourbons and 9 ryes). Then, subjects rated each whiskey sample on each attribute, using unstructured line scales, in standard good sensory‐evaluation conditions, and in triplicate. Results were analyzed using MANOVA, Barycentric Discriminant Analysis, and Hierarchical Cluster Analysis. Overall, while 10 descriptors significantly differentiated the whiskeys, no attribute or combination of attributes was predicted by mashbill: The judges did not find differences in sensory character between bourbon and rye whiskeys as categories. However, significant differences could be attributed to the producer of the whiskey and to age at bottling. These results are important because American whiskey has recently become staggeringly popular, and because there is a consistent belief that bourbon and rye whiskeys—as categories—have distinct sensory characteristics. Practical Application This research contradicts popular and expert beliefs about the distinction between the popular and important American rye and bourbon whiskeys. A comprehensive sensory DA study of 24 American whiskeys with different mashbills (9 ryes and 15 bourbons) shows that—while each whiskey is individually distinct on a number of sensory dimensions—sensory differences between rye and bourbon whiskeys as product categories cannot be predicted by mashbill. For producers, consumers, and researchers, this research points to the need for new theories on the origins of flavors in whiskey, as it is now clear that the grain content alone cannot predict sensory qualities.

Mashbill and barrel aging effects on the sensory and chemometric profiles of American whiskeys

“…These results indicate that mashbill does have an influence in sensory profiles, but also that the distinction may not be so apparent when ratios of grains in mashbill recipes are closer to parity, as is likely in many commercial bourbon and rye whiskeys . This may help explain the failure to find mashbill driven differences in American whiskeys up to this point . Therefore, while the results of this research support sensory attributes stemming from the mashbill, a question remains: at what ratio do these sensory differences emerge?…”

“…However, given the short range of aging times of the whiskeys in this study, it is impossible to rule out interactions emerging with longer aging. Certainly, in previous studies with whiskeys of greater age, researchers found that differences from mashbill were less apparent , which may point towards a convergence of whiskey flavours with aging. Thus, it is plausible that with longer aging time and blending practices, panellists would not be able to discriminate between the bourbon and rye whiskeys in this study.…”

“…It is known that aging time in new, charred‐oak barrels gives whiskey its colour and is related to ‘smooth’ and ‘rich’ flavour notes from the wood compounds . The cut‐off aging time for the experimental whiskeys in this study was two years, while most commercial whiskeys are aged longer or blended with whiskeys that have been aged beyond two years . If given more time for maturation, the sensory and chemometric profiles of these whiskey samples might differ dramatically.…”

“…A ‘free‐sorting’ sensory evaluation study of 10 commercially available American bourbon and rye whiskeys showed that although products were individually distinct, differences were not attributable to the whiskeys’ mashbill . A more recently published sensory descriptive analysis of 15 bourbon and nine rye whiskeys by Lahne et al found that whiskeys had distinct sensory profiles, and that these profiles did seem to depend on producer and aging time at bottling. However, the researchers concluded that no specific attributes were driven by mashbill—ryes and bourbons were not discriminable in this study.…”

“…In the literature on the sensory and chemometric profiles of American whiskeys, researchers could not effectively differentiate bourbons from ryes . A limitation of these studies is that the specifics of mashbill ratios and aging times of commercial American whiskeys are not readily accessible to researchers and consumers.…”