Aroma Perception and Chemistry of Bitters in Whiskey Matrices: Modeling the Old-Fashioned

Aim: The complex aromas of cocktails provide a unique and interesting model system to evaluate the effects of alcohol matrix and aroma-aroma interactions on human aroma perception and partitioning and release of aroma compounds. Here, we study the interactions that occur in an Old-Fashioned cocktail when different types of whiskeys are mixed with different styles of bitters. Methods: The interactions are studied in two ways, namely, by sensory descriptive analysis to evaluate changes in human aroma perception, and by headspace solid-phase microextraction and gas chromatography-mass spectrometry to study the volatile profiles individually and upon mixing. Results: Several aroma descriptors showed significant additive and suppressing interaction effects between bitters and whiskeys, and unique sensory characteristics were introduced by both bitters and whiskeys. Volatile compounds also showed suppressing and enhancing effects upon mixing of bitters with whiskeys. Conclusions: Such behaviors point towards chemical mixture effects and the enhancements in two compounds cannot be attributed to just the addition of certain bitters as the effects differ among the four whiskeys. Implications: These interactive sensory effects suggest further questions of interest about the inherent sensory complexity of foods and beverages; if sensory qualities in even simple cocktails, such as an Old-Fashioned, only exist upon mixing and for specific combinations of bitters and whiskeys, further unique interactions could be envisioned for more complex mixtures.