Oil and tastant concentrations affect saltiness and bitterness perception of oil-in-water emulsions

Saltiness of NaCl and KCl and bitterness of KCl and caffeine were evaluated in emulsions prepared with varying oil (20/40/60%) and tastant [NaCl (0.50/0.75/1.00%), KCl (0.50/1.00/1.50%) or caffeine (0.05/0.10/0.15%)] concentrations. A panel (N = 16) evaluated saltiness and bitterness intensities of emulsions using the modified short-version Spectrum (TM) descriptive analysis. Viscosity and pH of emulsions were measured. The type of tastant (NaCl/KCl/caffeine) and its concentration had significant effects on saltiness and/or bitterness intensities. At a given tastant concentration, NaCl had higher saltiness intensity compared to KCl in emulsions. Increasing oil concentration increased saltiness of both NaCl and KCl, while it slightly increased bitterness of KCl, but did not significantly affect bitterness of caffeine in emulsions. RSM plots indicated that saltiness enhancement of NaCl and KCl imparted by oil was more pronounced between 20% and 40% oil. Viscosity was the discriminating property among emulsions and possibly contributed to changes in salty and bitter perception.