Taste Exam: A Brief and Validated Test

Summary

This protocol measures human taste responses and includes a brief anatomical assessment, a short taste test, and a validation method using the subject's reported sensation and taste receptor genotype.

Abstract

The emerging importance of taste in medicine and biomedical research, and new knowledge about its genetic underpinnings, has motivated us to supplement classic taste-testing methods in two ways. First, we explain how to do a brief assessment of the mouth, including the tongue, to ensure that taste papillae are present and to note evidence of relevant disease. Second, we draw on genetics to validate taste test data by comparing reports of perceived bitterness intensity and inborn receptor genotypes. Discordance between objective measures of genotype and subjective reports of taste experience can identify data collection errors, distracted subjects or those who have not understood or followed instructions. Our expectation is that fast and valid taste tests may persuade researchers and clinicians to assess taste regularly, making taste testing as common as testing for hearing and vision. Finally, because many tissues of the body express taste receptors, taste responses may provide a proxy for tissue sensitivity elsewhere in the body and, thereby, serve as a rapid, point-of-care test to guide diagnosis and a research tool to evaluate taste receptor protein function.

Introduction

Measures of human taste perception can be both part of medical care and a target of biomedical research, yet taste has received scant attention compared with hearing and vision (Table 1). From the medical perspective, when clinicians evaluate patients complaining of taste loss, in most cases the actual loss is of smell¹, which has led to dismissal of taste loss as an uncommon and often invalid presenting complaint. Taste distortions (dysgeusia) are more common and frequently arise from the secondary effects of medications or peripheral nerve injury^2,3, but neither form ....

Protocol

The University of Pennsylvania Institutional Review board approved this protocol. We excluded subjects if they were under 18 years of age or were pregnant.

1. Oral Cavity Evaluation: Disease Assessment and Papilla Identification

1. Instruct the subject to open the mouth.
2. Using a light source such as a penlight or headlamp, illuminate the oral cavity and examine the seven subsites of the area (tongue, floor of mouth, buccal mucosa, labial mucosa, gingiva, hard palate, and retromolar trigone).
   1. Visualize the dorsal surface of the tongue. Instruct the subject to lift up the tongue, and examine the....

Results

Results from the taste test have been pooled for all subjects evaluated (n = 840) and are presented after segregation by genotype. The full data set is accessible at https://carayata.shinyapps.io/TasteBoxplots/ and can be reviewed for each tastant assessed and for TAS2R38 and TAS2R19 genotypes. Results confirm the existence of perceptual taste differences for PTC among subjects grouped by TAS2R38 receptor genotype (Figure 3). Rating.......

Discussion

The significance of this method is that it uses a multidisciplinary approach with features from medicine (the oral exam), experimental psychology (the taste test) and genetics (a validation step). Taste information is likely to develop as a diagnostic and prognostic tool because taste provides a window into the function of proteins elsewhere in the body. From an experimental psychology viewpoint, the addition of a simple exam can identify subjects who are not appropriate for the study of normative taste function. From a .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Disposable diagnostic penlight	Primacare	DL-9223
UltraLite Pro headlight	Integra LifeSciences	AX2100BIF
Millipore Q-Gard 2 water purification system	EMB Millipore	QGARD00D2
Denatonium benzoate	Sigma Aldrich	D5765
Phenylthiocarbamide	Sigma Aldrich	P7629
Quinine hydrochloride dihydrate	Sigma Aldrich	Q1125
Sodium Chloride	Sigma Aldrich	S1679
Sucrose	Sigma Aldrich	S0389
Glass scintillation vials	Thomas Scientific	1230L59	Same as Wheaton catalog no. 986580
Oragene Discover OGR-500 DNA collection kit	DNA Genotek	OGR-500
prepIT L2P Protocol reagents	DNA Genotek	PT-L2P-5
rs713598 TaqMan SNP genotyping assay	ThermoFisher Scientific	C___8876467_10
rs1726866 TaqMan SNP genotyping assay	ThermoFisher Scientific	C___9506827_10
rs10246939 TaqMan SNP genotyping assay	ThermoFisher Scientific	C___9506826_10
rs10772420 TaqMan SNP genotyping assay	ThermoFisher Scientific	C___1317426_10