Desensitization but not sensitization from commercial chemesthetic beverages

Sensations such as spiciness or stinging are particularly challenging to assess in sensory evaluation tests, as sensitization (increase in intensity with repeated tasting) and desensitization (decrease in intensity with repeated tasting) phenomena can confound intensity ratings. However, much of the published work on these phenomena are with model solutions or complex meals rather than commercial beverages. Thus, we tested whether we could observe sensitization or desensitization using canned spicy ginger beer (contained chili extract) and seltzer water. Samples were presented in pairs, with a 20 s wait and no rinse within a pair, but a 4 min wait with rinsing between pairs. Pairs of samples were: ginger beer followed by ginger beer, ginger beer followed by seltzer, seltzer followed by ginger beer, and seltzer followed by seltzer. These pairs were intended to allow us to also test for cross-sensitization/desensitization between the two beverages. Tests were conducted both in open cups and capped vials to observe how loss of carbonation influenced sample ratings. Participants tasted all pairs of samples in counterbalanced order and rated samples for intensity of “Spiciness, burning, or stinging sensation,” bitterness, sweetness, sourness, overall flavor, and liking/disliking. Results indicate no sensitization effects. Desensitization, however, likely occurred for both beverages. Further, tasting seltzer and ginger beer together in a pair amplified the “bitterness” of the seltzer water, a likely contrast effect. Overall, while sensitization may not interfere with the sensory ratings for these beverages, contrast effects and desensitization should be considered carefully when planning sensory evaluation tests.