Relationships Among Unpalatable Oral Stimuli, Saliva, Repeated Exposure, and Sensory Acceptance
Sensory perception and acceptance of disliked healthy foods can be improved through strategies such as repeated exposure. Yet, minimal work has investigated whether these approaches are effective in adult populations. Further, for interventions that do demonstrate modifications of perception or acceptance, we lack understanding of the full spectrum of contributing factors influencing the improvement of the sensory experience. For example, animal data suggest that factors such as saliva and salivary proteins are modifiable by diet and play a direct role in the perception of aversive bitter and astringent compounds, but minimal work has verified this in humans. Additionally, we know that there are myriad barriers and facilitators to healthy food consumption, but there are few investigations of these factors related to empirical assessments of liking. The work presented in this dissertation begins to address these gaps using untrained participants within a general student-aged adult population. We tested effects of repeated consumption of a bitter flavanol “tea” on bitterness intensity and salivary protein composition, demonstrating reduced bitterness intensity after repeated oral sensory exposure of the flavanol, with limited alterations in salivary protein composition attributable to flavanol exposure alone. Next, in a separate intervention, we tested the effect of repeated vegetable flavor exposure within a novel exposure matrix on liking of green vegetables. Using a game that challenged players to identify flavors in vegetable flavored gummy candies, we showed that repeated exposure using this method increased liking of initially disliked chopped vegetables. In a subsequent secondary analysis of data collected during this intervention, we identified variables related to sensory perception, food attitudes and behaviors, and other individual factors that explained variation in vegetable liking in ways that were unique between vegetables, underscoring the complexity of liking. Other chapters included in this dissertation accentuate these complexities through a methodological lens, providing evidence that stimuli choice, study population, and questionnaire design can all significantly impact results from sensory evaluations. Overall, repeated exposure is a promising strategy to help alleviate taste-related barriers to healthy eating in adults but is not a one-size-fits-all approach. Future work should investigate the generalizability of these methods in different adult populations and investigate impacts on dietary intake.
Running, Purdue University.
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