NCT03883880

Salivary Interactions With Chemosensations

• Status: Terminated
• Phase: N/A
• Study type: Interventional
• Enrollment: 32 (actual)
• Sponsor: Purdue University · Academic / Other
• Sex: All
• Age: 18 Years – 45 Years
• Healthy volunteers: Accepted

Summary

A counterbalanced, crossover design will be used to evaluate whether exposure to flavors vs. a control over time alters the perception of the flavor by changing an individual's salivary protein profile. Participants will complete 3 acute tasting protocols (baseline, after intervention 1, after intervention 2). The interventions will be with the flavor (epigallocatechin gallate, linolenic acid, capsaicin) or a control, in counterbalanced order, and will involve swishing and swallowing a solution of that sample 5 times per day for two weeks. Each of these flavors will be a separate sub-study.

Detailed description

This study is designed to test the relationship between salivary proteins, flavor sensation, and flavor exposure. For this study, we will test the bitterness/astringency of epigallocatechin gallate (EGCG, a polyphenol), the oleogustus (fatty acid taste) of linolenic acid, and the spiciness of capsaicin in conjunction with the concentration of specific salivary proteins (initially: salivary proline rich proteins for EGCG intervention, lipocalin-1 for the other two, but other proteins may be identified in the post-hoc analysis of the salivary proteome). We will test whether higher expression of these specific salivary proteins correlates with lower intensity of these flavors. We will further attempt to confirm the role of these salivary proteins using food-sourced functional analogs for these proteins. We would expect the food-sourced protein to have the same effect on flavor as the salivary protein if our hypotheses about salivary proteins' influence on flavor are correct. Finally, we will also use denatured versions of the food-sourced proteins to again confirm that effects are due to the function of these proteins binding the flavor. Additionally, we will repeatedly expose individuals to the flavors by having them rinse and swallow solutions of the flavor compounds multiple times per day for two weeks. We will then re-evaluate the sensory ratings and salivary protein profiles. Two weeks of rinsing and swallowing a control solution will be used as a control during this intervention (for each of the flavors of interest). To collect saliva and establish bitterness/astringency perception, we will use an acute tasting protocol. Participants will rinse with water, then taste and swallow, then taste and expectorate a solution of the flavor of interest. Saliva will be frozen for later proteomic analysis. Next participants will taste solutions of: flavor, flavor with food analog, the flavor with denatured food analog, water, water with the food analog, and water with denatured food analog. The participants will rank these solutions in order from least intense to most intense for the flavor quality of interest (bitterness/astringency for EGCG). After this, participants will taste all 6 samples again, and rate each individually for the intensity of the bitterness/astringency. After a short wait, this tasting and intensity rating will be repeated. All tastings will be done in counterbalanced order, and solutions will be labeled with randomized 3-digit codes. This acute tasting protocol will be done: at baseline, after 2 weeks on one intervention (repeated tasting of flavor or control), after 2 weeks on the other intervention.

Conditions

• Diet, Food Choice, Taste

Interventions

Type	Name	Description
OTHER	Epigallocatechin gallate	Colored solution prepared with epigallocatechin gallate to be consumed daily for two weeks during the epigallocatechin gallate intervention.
OTHER	Epigallocatechin gallate control	Colored control solution to be consumed daily for two weeks during the epigallocatechin gallate intervention.
OTHER	Linoleic acid	Colored emulsion prepared with linoleic acid to be consumed daily for two weeks during the linoleic acid intervention.
OTHER	Linoleic acid control	Colored control solution to be consumed daily for two weeks during the linoleic acid intervention.
OTHER	Capsaicin solution	Colored solution prepared with capsaicin to be consumed daily for two weeks during the capsaicin intervention.
OTHER	Capsaicin control	Colored control solution to be consumed daily for two weeks during the capsaicin intervention.

Timeline

• Start date: 2019-01-05
• Primary completion: 2019-09-24
• Completion: 2021-12-01
• First posted: 2019-03-21
• Last updated: 2023-05-25

Locations

1 site across 1 country: United States