Perceptual differences of aromas delivered through the orthonasal and retronasal routes

Aroma can be perceived through two routes: orthonasal (through the nose) and retronasal (through the mouth). The stimuli elicit signals that eventually reach the same receptors in the olfactory epithelium. However, previous studies suggest there is a perceptual difference between the two routes although the results are inconclusive. In this study, a matching paradigm was designed to control for memory bias and isolate the potential perceptual difference between aroma delivery routes. Panelists performed four matching paradigms of four different strawberry flavors (candy, woody, ripe, and green). The similarity of the four strawberry flavors required panelists to profile each sample to identify acute differences. This increased the cognitive demand required to complete the match. Subjects were given the four strawberry reference standards and told to either smell the sample orthonasally or taste it retronasally. Subjects then matched each reference to one of the four other blind-coded samples by either smelling or tasting congruently (same method) or incongruently (different methods). The retronasal samples consisted of 30 mL aqueous solutions in 2oz black sample cups, while the orthonasal samples consisted of 10 mL aqueous solutions in a capped glass vial wrapped in aluminum foil to minimize visual differences. When matching the reference to unknown samples using congruent evaluations, the panelists performed similarly in the orthonasal and retronasal tests (p=0.450) indicating they could correctly identify matching flavors. Performance significantly decreased when performed incongruently (p