Saltiness and Bitterness Perception of KCl-Based Mixed Salts (KCl/NaCl/L-Arginine) Evaluated by the R-Index and Partial Projective Mapping Methods

KCl, when used at a high concentration, imparts undesirable bitterness which can be suppressed using blockers such as L-Arginine (L-Arg). Sensory discrimination of saltiness and bitterness intensity of salt mixtures (KCl/NaCl/L-Arg) was determined by two methods: the R-Index (RIX) and Partial Projective Mapping (PPM). Four mixed salt solutions [KCl/NaCl/L-Arg: (A) 70/20/10, (B) 65/25/10, (C) 60/30/10, and (D) 55/35/10] at 0.5%, 1.0% and 1.5% w/v were prepared in order to impart different saltiness and bitterness perception, and compared to the control [100% NaCl; 0:100:0 (E)]. Using RIX, some degrees of differences in perceived saltiness and bitterness among salt mixtures were detected at all salt concentrations. However, using PPM, significant differences in saltiness and bitterness perception were not found between all salt mixtures and the control at 0.5% w/v. Both RIX and PPM methods could be used to discriminate saltiness and bitterness intensity among salt substitute mixtures and the control; however, the obtained results were conceptually distinct and must be interpreted cautiously based on the experimental test conditions used in this study.