The Impact of Subthreshold Carboxylic Acids on the Odor Intensity of Suprathreshold Flavor Compounds

Creative professionals, e.g., chefs and perfumers, often report that adding seemingly insignificant amounts of key ingredients can have an impact on aroma or flavor. Though a few studies suggest that subthreshold odors can enhance the rated intensity of very weak suprathreshold tastes and smells, there is little published evidence that subthreshold odors can enhance the rated intensity of odors or tastes of moderate intensity, such as one might commonly experience in foods and beverages. In the current study, experimenters added subthreshold concentrations of acetic and butyric acids to concentrations of three common flavor compounds that gave rise to moderately intense odors. Relative to the odor of the pure flavor compounds, subthreshold acetic acid increased the rated intensity of all compounds tested to a small but statistically significant degree. Further research is needed to fully understand such effects, but the results show that subthreshold odors can have a measurable impact on even moderate suprathreshold odors.