ORAL TACTILE SENSITIVITY AND MECHANISMS UNDERPINNING TEXTURE PERCEPTION.

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1017387
• Project Start Date: Oct 25, 2018
• Project End Date: Sep 30, 2023
• Program Code: [(N/A)]- (N/A)

Recipient Organization
OHIO STATE UNIVERSITY
1680 MADISON AVENUE
WOOSTER,OH 44691

Performing Department
Food Science & Technology

Non Technical Summary
Increasing attention of food manufacturers is directed towards texture due to its importance as a driver of liking. However, the mechanisms of texture perception in the mouth are not well understood. We believe texture perception is fundamentally a tactile (touch) sensation. This proposal aims to assess sensitivity of oral surfaces to a variety of tactile stimuli and correlate findings with perception and liking of food textures. In particular, we seek to compare sensitivity in the tongue, hard palate, cheek, and gums to punctate pressure, rough, and viscous stimuli at different temperatures or in the presence of flavor compounds that evoke sensations of temperature, irritation, or tingling. We believe that the perception and liking of various food textures will reflect the sensitivity of various oral surfaces to these basic tactile probes. Such knowledge will provide much needed insights as to how food textures are perceived and liked.

Animal Health Component

25%

Research Effort Categories

Basic

75%

Applied

25%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
502	7220	3090	100%

Knowledge Area
502 - New and Improved Food Products;

Subject Of Investigation
7220 - Sensory evaluation/analysis methods (human senses);

Field Of Science
3090 - Sensory science (human senses);

Keywords

food texture

perception

tactile sensitivity

threshold

suprathreshold

acceptability

Goals / Objectives
The primary objective of this proposal is to assess sensitivity of oral surfaces to a variety of tactile stimuli and correlate findings with perception and liking of food textures. In particular, we seek to compare tactile sensitivity in lingual, palatal (hard palate), cheek, and gingival tissues to punctate pressure, rough, and viscous stimuli at different temperatures or in the presence of other chemesthetic stimuli (e.g. menthol, capsaicin, sanshool, etc). We hypothesize that oral tissues will be differentially sensitive to the various tactile stimuli and that sensitivity will be modulated by the presence or absence of thermal or chemesthetic stimuli. Moreover, we hypothesize that food texture perception and liking will reflect tactile sensitivity.Sub Aim 1. We will assess and characterize the involvement of filiform papillae in viscosity perception. We hypothesize that the density and physical characteristics of filiform papillae (e.g. papillae length, radius of curvature, etc.) will associate with threshold and suprathreshold sensitivity to viscosity.Sub Aim 2: We will assess sensitivity of the tongue, hard palate, cheek, and gingiva to punctate pressure, astringent, rough, and viscous stimuli. We hypothesize that oral tissues will display differentiable sensitivity.Sub Aim 3: We will assess the impact of tactile sensitivity on the perception and liking of food textures. We hypothesize that oral tactile sensitivity will associate with food texture perception and liking.Sub Aim 4: We will assess how tactile sensitivity of various oral tissues is modulated by cold or warm temperatures. We hypothesize that tissue sensitivity will be maximal at 37°C.Sub Aim 5: We will assess how tactile sensitivity of various oral tissues is modulated by the presence of chemesthetic flavor compounds (e.g. menthol, capsaicin, sanshool, etc.). We hypothesize that tactile sensitivity will decrease in the presence of these compounds.

Project Methods
Threshold and suprathreshold psychophysical methodologies will be utilized to assess mechanosensitivity of oral tissues to various tactile stimuli. Sub Aim 1: The involvement of filiform papillae in viscosity perception will be assessed. Model solutions of varying viscosity will be developed using carboxymethyl cellulose (CMC). Just noticeable difference thresholds will be assessed using the forced-choice, staircase method. Suprathreshold sensitivity will be assessed using magnitude scaling. For each panelist, filliform papillae density, height, and radius of curvature will be determined from high resolution images using optical profilometry. Threshold and suprathreshold viscosity sensitivity will be correlated with filiform papillae characteristics. Sub Aim 2: The sensitivity of the tongue, hard palate, cheek, and gingiva to punctate, astringent, rough, and viscous stimuli. Punctate pressure sensitivity will be assessed using a Cochet-Bonnet aesthesiometer. Sensitivity to astringent compounds will be assessed using tannic acid and/or epigallcatechin galleate. Roughness sensitivity will be assessed using roughened stainless steel metal bars. Viscosity sensitivity will be assessed using CMC solutions. For each tissue and stimulus type, threshold and suprathreshold sensitivity will be assessed. Just noticeable difference thresholds will be assessed using the forced-choice, staircase method. Suprathreshold sensitivity will be assessed using magnitude scaling. Sensitivity of different oral tissues will be compared using paired t-tests. Sub Aim 3: Liking of food textures will be assessed by asking subjects completing Sub Aim 2, to rate the desirability and/or acceptability of a variety of foods varying in texture. The association between tactile sensitivity and food liking/desirability will be assessed using linear and/or non-linear regression analysis.Sub Aim 4: The sensitivity of the tongue, hard palate, cheek, and gingiva to astringent, rough, and viscous stimuli will be assessed at varying stimulus. Punctate pressure sensitivity will be assessed using a Cochet-Bonnet aesthesiometer. Sensitivity to astringent compounds will be assessed using tannic acid and/or epigallcatechin galleate. Roughness sensitivity will be assessed using roughened stainless steel metal bars. Viscosity sensitivity will be assessed using CMC solutions. For each tissue and stimulus type, threshold and suprathreshold sensitivity will be assessed when the stimulus is cooled (to 6°C) or warmed (to 45°). Just noticeable difference thresholds will be assessed using the forced-choice, staircase method. Suprathreshold sensitivity will be assessed using magnitude scaling. Sensitivity of different oral tissues to stimuli varying in temperature will be compared using analysis of variance.Sub Aim 5: The sensitivity of the tongue, hard palate, cheek, and gingiva to astringent, rough, and viscous stimuli will be assessed in the presence or absence of compounds evoking thermal (e.g. menthol, camphor), nociceptive (e.g. capsaicin), or tingling (sanshool) stimuli. Punctate pressure sensitivity will be assessed using a Cochet-Bonnet aesthesiometer. Sensitivity to astringent compounds will be assessed using tannic acid and/or epigallcatechin galleate. Roughness sensitivity will be assessed using roughened stainless steel metal bars. Viscosity sensitivity will be assessed using CMC solutions. For each tissue and stimulus type, threshold and suprathreshold sensitivity will be assessed before and after a given chemesthetic compound is applied to the oral tissue of interest. Just noticeable difference thresholds will be assessed using the forced-choice, staircase method. Suprathreshold sensitivity will be assessed using magnitude scaling. The impact of chemesthetic stimuli on the mechanosensitivity of different oral tissues will be compared using analysis of variance.

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:The target audience engaged by these efforts include the food and beverage industry, academicians within the fields of food science, and clinicians and scientists studying swallowing disorders. Efforts to engage industrialstakeholders included hosting multiple visits by industry personnel to discuss this research, presenting findings atmultinational companies, and presentations at relevant symposia including the Institue of Food Technologists andthe International Symposium on Taste and Smell. Efforts to engage the academic community havealso occured through presntations at these same symposia as well as scholarly presentations at Colorado State University. Students in the Ohio State University Food Product Development,Measurement of FoodPerception and Liking, and Advanced Sensory Sciencecourses have also been exposed to the outcomes of this research. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided research training opportunities for four graduate students. Professional development opportunities were obtained by hosting multiple visits by industry personnel to discuss this research and presenting research findings at seminars hosted by multinational food companies, academic seminars, and professionalsocieties and conferences. How have the results been disseminated to communities of interest?The results have been disseminated to communities of interest through publications (manuscripts and abstracts) and presentations at conferences and seminars organized and/or attended by academica and industry stakeholders. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we plan to (1) associatetactile sensitivty to food choicein picky and non-picky eaters; (2) determine how suprathreshold roughness sensitivity in the tongue is influenced by temperature; (3) relate high viscosity sensitivity to anatomical and physiological features of the hard palate.

Impacts
What was accomplished under these goals? During this reporting period, we completed 2 studies assessing sensitivity of oral surfaces to a variety of tactile and somatosensory stimuli. In study 1, roughness just-noticeable difference thresholds were compared across various oral tissues including the tongue, hard palate, cheek, lip, and gums. Sensitivity was greatest on the tongue, followed closely by the hard palate. This result further supports the role of the tongue and hard palate in sensing and differentiating food related textures. In a second study, we compared capsaicin sensitivity in these same tissues across Caucasian-American and Indian cultural groups. When the study populations were matched for frequency and liking of spicy food consumption, no differences in sensitivity at any anatomical site were noted. Two additional studies were initiated during this reporting and are ongoing. In study 3, texture liking and disliking was assessed in picky and non-picky children using conjoint analysis. Suprathreshold lingual sensitivity to roughness, edges, points, viscosity, and firmness was assessed in these same subjects. Associations between tactile sensitivity, texture liking, and pickiness are being explored. In study 4, the impact of temperature and chemesthetic compounds on lingual suprathreshold roughness sensitivity is being assessed. Future studies aim to assess effects of temperatures on tactile sensitivity in other oral tissues.

Publications

• Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Miles BL and Simons CT. Elucidating a potential detection mechanism for high-viscosity solutions in the oral cavity. Presented at the International Symposium on Taste and Smell, August 2020.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Berry D.N. and Simons C.T. Assessing regional sensitivity and desensitization to capsaicin among oral cavity mucosae. Chemical Senses. 45(6): 457-466, 2020.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Berry D.N. and Simons C.T. Do Caucasian American and South Asian Indian cultural groups differ in sensitivity to capsaicin? A study designed to control for chili pepper affinity. Journal of Food Science. 85(9): 2896-2901, 2020.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Miles B.L., Ang S.L. and Simons C.T. Development of a pure-tactile assessment of edge discrimination in the hands and oral cavity. Physiology & Behavior. 224: e113035, 2020.
• Type: Book Chapters Status: Awaiting Publication Year Published: 2020 Citation: Carstens E., Simons, C.T. Oral Chemesthesis and Taste. In: The Senses: A Comprehensive Reference. Vol III. Olfaction and Taste., 2nd edition, edited by W. Meyerhof. London: Elsevier, In press.
• Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Andes A. and Simons CT. Assessing the Impact of Negative Versus Positive Textural Drivers on Eating Choices. Presented at the Institute of Food Technologists Annual Meeting, July 2020.
• Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Berry DN and Simons CT. Determination of sensitivity differences to a burning chili pepper compound between Caucasian American and Indian cultural groups after control of external factors. Presented at the Institute of Food Technologists Annual Meeting, July 2020.
• Type: Conference Papers and Presentations Status: Other Year Published: 2020 Citation: Berry DN and Simons CT. Regional effects of capsaicin in the oral cavity: comparing sensitivity and characterizing desensitization among the tongue, cheek, hard palate, and lip mucosae. Presented at the International Symposium on Taste and Smell, August 2020.

Progress 10/25/18 to 09/30/19

Outputs
Target Audience:The target audience engaged by these efforts include the food and beverage industry, academicians within the fields of food science, and clinicians and scientists studying swallowing disorders. Efforts to engage industrial stakeholders included hosting multiple visits by industry personnel to discuss this research, presenting findings at multinational companies, and presentations at relevant symposia including the Institue of Food Technologists, the Society for Sensory Professionals,and the Pangborn SensoryScience Symposium. Efforts to engage the academic community have also occured through prresntations at these samesymposia as well as scholarly presentations at the University of Florida Smell and Taste Center. Students in the Ohio State University Food Product Development and Measurement of Food Perception and Liking courses have also been exposed to the outcomes of this research. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project provided research training opportunities for three undergraduate and fourgraduate students. Professional development opportunities were obtained by hosting multiple visits by industry personnel to discuss this research and presenting research findings at seminars hosted by multinational food companies, academic seminars, and professional societies and conferences. How have the results been disseminated to communities of interest?The results have been disseminated to communities of interest through publications (manuscripts and abstracts) and presentations at conferences and seminars organized and/or attended by academica and industry stakeholders. What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, we plan to (1) assess how tactile sensitivty impacts food choices in picky and non-picky eaters; (2) determine how suprathreshold roughness sensitivity in the tongue is influenced by temperature;(3) relatehigh viscosity sensitivityto anatomical and physiological features of the tongue and palate.

Impacts
What was accomplished under these goals? During this reporting period, we completed 5 studies assessing sensitivity of oral surfaces to a variety of tactile and somatosensory stimuli. In study 1, edge detection was compared on the anterior tongue to the fingertip. Subjects were able to discriminate edges significantly better with their tongue compared to their fingertips. In study 2, the same stimuli were used to assess edge sensitivity across various oral tissues including the tongue, hard palate, cheek, lip, and gums. Sensitivity was greatest on the tongue, followed closely by the hard palate. These same tissues were also assessed for sensitivity to punctate stimuli and capsaicin in studies 3 and 4. Similar results were found with sensitivity being greatest on the tongue followed closely by the hard palate. These results underscore the exquisite sensitivity of the tongue to tactile and chemesthetic stimuli, however also indicate high sensitivity of the hard palate, an oral tissue that is vastly understudied in texture perception and somatosensory research. Studies 1, 2, and 3 were completed by undergraduate researchers that enabled graduating with a Research Distinction. In study 5, we characterized the perception of high-viscosity (η<1500cP) solutions and utilized oral tissue isolation paradigms to help elucidate a detection mechanism. Results suggest the tongue plays a critical but different role in viscosity perception dependent upon the individual. Some individuals, particularly those worse at the task, may be using the roof of the mouth to provide clues on solution viscosity. Future studies evaluating the role of this structure in viscosity perception, as well as potential physiological differences between the two groups may provide further insight into high-viscosity discrimination.

Publications

• Type: Journal Articles Status: Published Year Published: 2018 Citation: Comparative tactile sensitivity of the fingertip and apical tongue using complex and pure tactile tasks. Physiology & Behavior. 194:517-521, 2018.
• Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Assessing regional sensitivity and desensitization to capsaicin among oral cavity mucosa. Chemical Senses. Submitted
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Exploring oral tactile sensitivity. Presented at the Pangborn Sensory Science Symposium, Edinburgh, Scotland, August 1.
• Type: Conference Papers and Presentations Status: Other Year Published: 2019 Citation: Elucidating a potential detection mechanism for high-viscosity solutions in the oral cavity using tissue isolation. Presented at the Pangborn Sensory Science Symposium, Edinburgh, Scotland, July 29.
• Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Comparative tactile sensitivity of the fingertip and apical tongue using complex and pure tactile tasks. Presented at the Society of Sensory Professionals Symposium, Cleveland, Ohio, Sept 28..