The Interaction of Mixing Odorants with Similar Chemical Properties: A Case Study on Ketone Compounds

Abstract

To investigate more about the interaction of mixing odorants, a series of sensory tests were conducted using five ketones [butanone (Bu), 2-Pentanone (Pe), 2-Hexanone (Hex), 2-Heptanone (Hep), 2-Octanone (Oc)] at varying concentration levels. The determination of odor threshold (OT) was initially conducted by the triangle odor bag method (GB/T 14675, China). The odor activity values (OAVs) of individual odorants at a wide range of concentrations were derived from concentration-to-odor threshold ratios. The resulting data were then evaluated to define the empirical relationship for each ketone between the OAV and odor intensity (OI) scaling. Based on the relationships defined for each individual ketone, the OI values were estimated for a synthetic mixture of five ketones. The effect of mixing was then examined by assessing those estimated OI values with the actually measured OI values. The overall results of this study confirmed that the OI values of the synthetic mixture is not governed by the common theoretical basis (e.g., rule of additivity, synergism, or a stronger component model) but is best represented by the averaged contribution of all ketone components. Thus, the odor intensity (OI) of a given mixture sample containing odorants with similar chemical properties can be accessed through the conversion from its concentration value with the application of empirical equations instead of direct measurement by the human test panel.