Psychophysical Effects of Increasing Oil Concentrations on Saltiness and Bitterness Perception of Oil-in-Water Emulsions

Limited research has been done to investigate saltiness and bitterness perceptions of NaCl, KCl, and caffeine in emulsion systems. Saltiness and bitterness intensities of emulsions prepared with different concentrations of oil [0% (that is, solution), 20%, 40%, canola oil] and different concentrations of 3 tastants (NaCl [0.5% to 1.0%], KCl [0.5% to 1.5%], and caffeine [0.05 to 0.15%]) were measured using the Spectrum™ descriptive method (N = 16) and the Electronic-tongue (E-tongue). Linear regression and the Stevens' power law were used to model the taste intensities against the tastant concentrations. From the descriptive data, saltiness intensities in emulsions were higher than solutions, demonstrating a saltiness-enhancing effect imparted by oil. Bitterness intensities in emulsions were lower compared to those of solutions for caffeine, but they were similar for KCl. This demonstrated that oil suppressed bitterness for caffeine. E-tongue saltiness measurements were corresponding to those of the descriptive data; however, E-tongue bitterness intensities of KCl showed an opposite pattern. Practical Application: We evaluated saltiness intensities of NaCl and KCl, bitterness intensities of caffeine, and KCl in oil-in-water emulsion systems at different oil and tastant concentrations using a descriptive panel and the Electronic-tongue (E-tongue). Overall, this study demonstrated that oil exhibited a saltiness-enhancing effect in NaCl and KCl emulsion systems, and oil exhibited a bitterness-supressing effect for caffeine in emulsion systems. Saltiness intensities from the E-tongue were congruent with those from the descriptive panel. However, bitterness intensities from the E-tongue were negatively correlated with those from the descriptive panel. These findings are useful for understanding saltiness and bitterness perception in emulsions.