The Perceived Intensity and Agreeability of Sensory and Chemesthetic Stimuli, and Identification of Taster Type Among a Non-Dysphagic Female Population

TASTERS, SENSORY AND CHEMESTHETIC STIMULI

The perceived intensity and agreeability of sensory and chemesthetic stimuli, and identification of taster type among a non-dysphagic female population.

Anya Smyth

Supervisor: Dr. Arlene McCurtin Student Number: 12011762 Final Word Count: 8,230

This research paper has been formatted for submission to Dysphagia

A research paper submitted in partial fulfillment of the requirements for the Masters of Science Degree in Speech and Language Therapy, May 2014 Abstract

Bolus modifications, compensatory strategies, are commonly used in dysphagia therapy, but often limited by accompanying factors to pathologies such as cognitive and communication deficits, poor compliance and fatigue. Previous researchers have hypothesized that swallow functions can be improved through the excitement of neural pathways, yet the role of taste, which is significant in choice and preference of food, remains largely under-researched. Perception of taste is dependent on the tongues density of fungiform papillae (Bartoshuk 1994), and further investigation into how taste is perceived by different tasters has the potential to benefit future dysphagia research, and the development of assessment and therapy tools. This pilot study aimed to collect preliminary data, identifying sensory and chemesthetic stimuli that provoke the strongest reactions in a non-dysphagic population, to be utilized in the development of dysphagia assessment and treatment tools. It also investigates if the identification of taster types can be of use in the domain of dysphagia. 108, non-dysphagic, female volunteers, aged 18-50 were recruited. Fungiform papillae were measured using a blue-dye test and participants rated the perceived intensity and agreeability of 54 taste stimuli. Taster identification does not appear to pertain to dysphagia therapy or research, no differences were found among the tasting groups and tasters had no significant relationship to perceived intensity or agreeability. Individual tastes such as sweet, perfumed and minty, and several prospective groups were identified that have the potential to be beneficial in future dysphagia therapy research that could allow the continuation of typical eating habits.

Keywords: Dysphagia, Sensory, Chemesthetic, Taste, Fungiform Papillae, Intensity, Agreeability

ii Acknowledgements

Through out the writing of this research project lots of knowledge and experience has been acquired which would not have been possible without the support and co-operation of other people.

First of all, I would like to express my sincere appreciation to my supervisor Dr. Arlene McCurtin for the guidance, motivation and instrumental role played throughout the research process.

I also owe a debt of appreciation to Anita Condron, Maurice Hartnett, and of course Claire Hartery, whose partnership and support made this study a pleasure. Of course a heart felt thank you to my fiancé, Eoghan, whose support and encouragement has kept me motivated (and fed) not only for this project, but also over the last two years.

Last but not the least the participants who volunteered their time and tongue’s, without them there would have been no study.

iii Table of Contents

1 Introduction 1.1 Dysphagia 1 1.2 Taste 2 1.3 Perception of taste 5 1.4 Influence of intensity and agreeability 6 1.5 Research aims 7

2 Methodology 2.1 Participants 8 2.2 Materials 8 2.3 Procedures 9 2.4 Data analysis 12 2.5 Ethical considerations 13

3 Results 3.1 Tests of normality 14 3.2 Taster types and strongest reactions 14 3.3 Associations between Perceived Intensity and Agreeability 16 3.4 Tasters and tastes 17 3.5 Identification of tastes for future development 19

4 Discussion 4.1 Principle findings 22 4.2 Implications 27 4.3 Limitations 27 4.4 Summary 28 4.5 Conclusions 28

Reference List 29

Appendices 1 Recruitment email 35 2 Advertising poster 36 3 Information leaflet 37 4 Consent form 38 5 Questionnaire 39 6 Taster status information 53 7 Tests of normality – Shapiro Wilk 54 8 Q-Q plots, histograms, boxplots, skewness and kurtosis 55 9 Factor loadings- Perceived Intensity 56 10 Factor loadings – Agreeability 58

iv List of Tables

2.1 Taste stimuli 2.2 Taster category 3.1 Spearman’s correlation coefficient 3.2 Directly related stimuli 3.3 Inversely related stimuli 3.4 Factor analysis loadings of Perceived Intensity 3.5 Reliability of Perceived Intensity 3.6 Factor analysis loadings of Agreeability 3.7 Reliability of Agreeability

List of Figures

1.1 Filiform Papillae 2.1 Analysis of blue dye test 2.2 Rating scales –Perceived Intensity 2.3 Rating scales – Agreeability 3.1 Overall Medians – Perceived Intensity 3.2 Overall Medians – Agreeability 3.3 Tasters and fudge 3.4 Mann Whitney 3.5 Mann Whitney - significance 3.6 Scree plot – Perceived Intensity 3.7 Scree plot- Agreeability

v Introduction

1. Introduction.

1.1. Dysphagia

Swallowing is a life sustaining function, essential for food ingestion and is controlled by a diffuse, bilateral cerebral system (Ertekin and Aydogdu 2003). An inability to swallow, or dysphagia, occurs as a result of anatomical abnormalities or physiologic disturbances to the oral cavity, pharynx, larynx or esophagus. These presentations can be congenital (e.g. cerebral palsy), caused by sudden neurological damage (e.g. stroke, traumatic brain injury), or gradual (e.g. Parkinson’s disease, Multiple sclerosis), (Logemann 1998). The presence of dysphagia places a person at risk of malnutrition, dehydration and/or aspiration pneumonia. A speech and language therapist seeks to implement an intervention that aims to reduce and/or eliminate the risk of aspiration through the use of rehabilitative approaches and compensatory strategies. A recent study by McCurtin (2012) found compensatory strategies texture modification, thickening of fluids and changes of posture to be the most commonly used techniques in dysphagia therapy in Ireland. However, the evidence to support this approach is weak and research has found that people prescribed thickened liquids have a higher incidence of pneumonia and rarely meet their fluid intake requirements (Finestone et al. 2001; Logemann et al. 2008). Accompanying factors such as cognitive and communication deficits, poor levels of compliance and general fatigue limit the potential of these methods to benefit the dysphagic population (Sdravou et al. 2012). The need for compensatory strategies requiring fewer physical and cognitive demands on the dysphagic person has been highlighted through out the literature.

Compensatory strategies using the modification of bolus properties taste, temperature, volume, and texture have been found to modulate swallowing behavior through adaptation of biomechanical and temporal measures in both healthy adults and the dysphagic population (Rofes et al. 2012; Ebihara et al. 2006; Pelletier and Steele 2014; Ding 2003; Sdravou et al. 2012; Logemann et al. 1995; Pelletier & Lawless 2003; Cola et al 2010;

Sciortino et al. 2003; Ebihara et al. 2005). These studies have suggested increased sensory input can influence the swallow by the neural excitement of the peripheral sensory receptors in the taste buds, approximating the sensory threshold of swallows in the brainstem, leading to a stronger, prompter swallow and a reduction in aspiration.

1 Introduction

1.2 Taste Taste has often been cited as the most significant factor in food choice and preference (Feeney et al. 2011; Schwartz et al. 2009) and food behaviour is guided by our preferences in taste and flavor (Clark 1998). Although the human tongue is able to recognize many different taste compounds, there are five classical perceptual taste qualities: sweet, salty, sour, bitter and umami (the oral sensation stimulated by salts of glutamic or aspartic acids, [Lawless and Heymann 2010]). Our sense of taste is contained in receptors on the tongue, fungiform papillae, which when activated lead to oral sensations. Oral chemesthesis is innervated by the trigeminal nerve, which is the main chemosensory pathway along with the cranial nerves IX (glossopharyngeal) and X (vagus). Tastes such as salty or sweet have been found to heighten the activation of the facial nerve as its braches innervate the taste buds in the more anterior folds of the foliate papillae (Ding et al. 2003). The glossopharyngeal nerve innervates the posterior part of tongue and the upper pharyngeal region which are more sensitive to sour and bitter tastes (Frank and Smith 1991).

Figure 1.1 – Filiform papillae Physiological changes in swallowing have been found to result from normal aging. In the healthy older individual, overall tongue movement during the early portion of the swallow is slower, and the triggering of the pharyngeal phase of the swallow is more delayed. Absolute taste thresholds typically rise in advanced age, and older individuals have difficulty detecting and recognizing taste, as well as difficult discriminating between tastes. While taste is such a significant factor in our choice and preference of foods, few studies have investigated its influence on swallow. Correspondingly, a thorough examination of the effects of manipulating food characteristics, taste and chemesthesis, on swallowing has not yet been carried out extensively in humans. Knowledge of how different tastes provoke different reactions anatomically and physiologically will be of great benefit in the development of dysphagia research.

2 Introduction

Taste such as sour (Logemann et al. 1995; Pelletier and Lawless 2003; Pelletier and Dhanaraj 2006; Cola et al. 2010), sweet (Pelletier and Lawless 2003; Prescott et al. 2001), capsaicin (Ebhiara et al. 2005; Rofes et al. 2012), and chemesthetic properties such as the cooling sensation of menthol (Ebhihara et al. 2006) or the irritant of carbonated fluids (Sdravou et al. 2012; Bülow et al. 2003; Miura et al. 2009) have received some consideration with particular regard to dysphagia. Furthermore it has been clinically accepted that thermal stimulation using a cold stimulus restores sensitivity to trigger the swallowing reflex in dysphagic patients (Cola et al. 2012; Lazzara et al. 1986).

Sour In studies carried out by Logemann et al. (1995) and Pelletier and Lawless (2003), an improvement in the onset of the oral phase and the pharyngeal phase was found using a sour liquid bolus. Here the researchers hypothesized that swallow responses were triggered by a rapid increase in saliva as a result of the sour bolus, facilitating a more organized swallow by increasing pre-swallow sensory input, allowing for more rapid approximation of the threshold required for triggering a swallow. However participants found the sour bolus to be tolerable but unpleasant, thus limiting its use as a therapeutic strategy (Pelletier and Lawless 2003). Sour, sweet, salty Using a different method of investigation Ding et al. (2003) and Palmer et al. (2005) used surface electromyography (sMEG) to investigate the effects of sour, sweet and salty tastes, and viscosity on the intensity and timing of muscle contractions of the lips and sub mental and infra-hyoid muscles. The authors found the sour bolus resulted in shorter onset times and stimulation of muscle activity in a younger group of participants. Similar conclusions were made by Miura et al. (2009), using a sour, carbonated and cold bolus. Ding et al. (2003) also concluded similar findings when using a sweet bolus. In addition they also found no significant change in muscle behaviour in the older group of participants, which was presumed to be due to a reduction in sensitivity to taste with age. Similarly Palmer et al. (2005) reported an increased muscle behaviour using salty bolus when compared to a sweet and sour bolus. However, Hamdy et al. (2003) found contradictory results as instead of facilitating swallows, liquid sour boluses decreased the capacity and speed of swallow, which was particularly evident if the bolus was also cold.

3 Introduction

Temperature Although the effect of temperature on swallowing is difficult to determine, as studies have not reported stimulus temperature, thermal stimulation has already been identified as a beneficial tool in dysphagic therapy, which is achieved using a cold laryngeal mirror lightly touching the anterior faucial pillars and the application of small amounts of iced fluids (Lazzara et al. 1986). However, Hamdy et al. (2003) found no improvement of inter-swallow interval, swallowing velocity or volume per swallow using a 4°c cold water stimulus when compared to room temperature in young and elderly healthy adults or adults post stroke. Bisch et al. (1994) did find cold fluids created significantly longer pharyngeal response times and longer laryngeal elevation in adults post stroke and healthy adults swallowing using 1ml, 0.5°C boluses compared to room temperature boluses and authors suggested a near- freezing bolus was particularly effective in improving swallowing parameters. Cola et al. (2010) identified a cold stimulus amplified the effect of sour stimuli on swallowing in adults with dysphagia. Menthol Menthol, a chemical agent found in mint, proved to be a more efficient and effective method than the procedure of thermal stimulation (Ebihara et al. 2006 a). Menthol is believed to have a similar chemesthetic response as cold stimuli. Ebihara et al. (2006 a) found that flavoured menthol lozenges, consumed and dissolved before meals were affective in reducing the risk of aspiration and improving the sensitivity of the swallow reflex in an elderly population. This is of particular interest as its ease of use compared to other methods could make it particularly useful when working with communication and cognitive deficits. Capsaicin

In contrast to the cold and menthol sensations, capsaicin has been found to have a strong therapeutic effect in dysphagia (Ebihara et al. 2005; Rofes et al. 2012). In a similar method to that used for menthol, Ebihara et al.(2005) found a capsaicin lozenge to improve the swallow reflex in the elderly. In a later study, Ebihara et al.(2006 b) further investigated the use of capsaicin (black pepper) oil via nasal inhalation prior to eating, and reported decreased swallowing response delay. The authors accredit this to the role of the insular cortex of the brain in both dysphagia and appetite stimulation. However this study involved

4 Introduction olfactory stimulation and does not indicate if participant’s found the black pepper oil tolerable. Carbonation In order to identify liquids that are both palatable and usable to reduce aspiration some key studies have identified the influence of carbonated liquids on swallowing in adults with dysphagia (Bülow et al. 2003; Sdravou et al. 2012; Miura et al. 2009). Bülow et al. (2003) and Sdravou et al. (2012) both found that carbonated liquids significantly reduced penetration/aspiration into the airways, pharyngeal transit time and pharyngeal retention, when compared to thin fluids. Steel & Miller (2010) suggest further investigation into the use of carbonation in dysphagia is warranted as they hypothesize that the gas in a carbonated bolus acts as a touch pressure stimulus and a dynamic taste or chemesthetic stimuli, but also suggest it may be limited by its un-palatability. However Sdravou et al. (2012) reported that only one of 17 participants found the carbonated stimulus unpalatable.

Some studies have identified taste and chemesthetic stimuli that have potential to strongly improve the safety and efficacy of dysphagic therapy justifying the need for further investigation however further consideration needs to be applied to gustatory properties such as palatability and intensity of taste (Lindermann 1996; Smith and Margolskee 2001). Additional attention needs to be paid to manner by which individuals perceive taste and its intensity, as well as possible differences as to why some people prefer some tastes to others (agreeability).

1.3 Perception of taste Research into the perception of taste has spanned over decades, pioneered by Linda Bartoshuk, and evidence has shown that the differences in taste perception arise from underlying anatomical differences (Prescott et al. 2001). Perception of intensity is dependent on the density of fungiform papillae on the tongue (Bartoshuk et al. 1994, Miller and Reedy 1990). The population is divided into two tasting groups those who are non- tasters, and those who are medium or supertasters. Correlations between the ratings of intensity and the density of fungiform papillae have been found, with higher numbers of papillae commonly found in people classified as supertasters. Supertasters have often been

5 Introduction identified by their intense response to the bitter substance 6-n-propylthiouracil (PROP) (Bartoshuk 1994; Shahbake et al. 2005; Miller and Reedy 1990; Fischer et al. 2012).

Miller and Reedy (1990) also discovered anatomical difference between tasters using the blue dyes that differentially stain the structures of the tongue. The dye fails to stain the fungiform papillae, leaving them visibly pink, and easy to count under magnification. The chorda tympani nerve innervates 25% of the fungiform, while the other 75% are innervated by the trigeminal nerve (Beidler 1969). The trigeminal nerve fibers surround each of the taste buds and terminate in the apex of the fungiform papillae, an area less keratinized, thus providing better access for pain stimuli (Bartoshuk 2000). While there has been much investigation into the variability of taster responses to PROP, a body of research has shown supertasters to also be more sensitive to the bitterness of caffeine, potassium chloride, sodium benzoate, potassium benzoate and isohumulones, other taste categories such as sweet-bitter, sweet-sour, salty-bitter, salty-sour, and trigeminal sensations or chemesthetic reactions such as the irritation of alcohol or capsaicin, the fizz of carbonated fluids, the burn from chili or spicy foods, or the cooling sensation of menthol (Bartoshuk et al. 1994; Prescot et al. 2001). Thus knowledge of taster preference and level of sensitivity may be of some benefit in dysphagia therapy.

1.4 The influence of intensity and agreeability

To date, the influence of taste on the physiology of swallowing remains indefinite but the findings and hypothesis of the majority of these papers lead us to consider modulating and treating dysphagia using taste and chemesthetic means. Although these studies compare the effects of different tastes on swallowing, no studies have sought to establish equivalent taste intensities, which could contribute to an overall increase in sensory input. It is important to consider the implications that the intensity and agreeability of different tastes could have on the therapy techniques employed by clinicians working with the dysphagic population. Although liquid boluses are used most frequently, a bolus taste consistency that allows for adequate stimulation of the taste buds while reflecting normal eating habits would be ideal, such as the lozenge used by Ebihara (2005; 2006a).

6 Introduction

In order to discover the potential impact of sensory and chemesthetic properties, we need to consider perceived intensity and agreeability of stimuli and affective experiences of these. While is has been suggested that pleasant tastes stimulate different cortical areas, it is not known yet if hedonics (likes v dislikes) influence our swallowing physiology (Pelletier and Lawless 2003). It would be of benefit to determine if particular tastes produce a better swallow response that could be beneficial in therapy by the nature of its intensity and its agreeability.

1.5 Research Aims This study hopes to combine two large bodies of research, the use of sensory and chemesthetic stimuli and the identification of taster types, to determine if they can be of conjoint relevance in dysphagia therapy. The overall aim is to gain preliminary data that could be used in modulating the further development of swallow assessment and therapy tools. It is also hypothesized that there is a direct link between the density of papillae on the tongue and the perception of intensity and the agreeability of taste stimuli that could also be of benefit in further dysphagia research. It is expected that there will be similarities between taster groups and their perceived intensity and agreeability of taste stimuli. This will be achieved by answering the following research questions:

1. How is the Irish population divided in terms of taster status and can this classification be useful in assessment of therapy of dysphagic populations? 2. What sensory and chemesthetic stimuli provoke the strongest reactions of perceived intensity and agreeability in a non-dysphagia population? 3. Is a relationship between taster categories and those tastes that provoke the strongest reactions? 4. What stimuli may be subsequently utilized in the future development of reliable sensory and chemesthetic assessment and treatment tools for dysphagia?

7 Methodology

2. Methodology

2.1 Participants The participants chosen for this simple, random sample, pilot study were 108 non- dysphagic healthy female volunteers between the ages of 18-50 years. Women were recruited because they are statistically more likely than men to be supertasters (Bartoshuk et al. 1994).

20-40 participants is an adequate sample size for documenting sensory difficulties for discrimination purposes (Lawless and Heymann 2010) and one gender group was recruited to account for 3 sensory classifications (Supertasters, Medium tasters, Non–tasters) a maximum of 120 were intended to be recruited. A cut off of 50 years of age was applied as the taste detection thresholds decrease with age (Methven et al. 2012).

Other exclusion criteria included; a history of smoking within the last 6 months; a history of ear nose and throat difficulties including surgery, allergies or presenting with a cold, flu or respiratory tract infection on the day of testing; oral difficulties such as gum disease, xerostomia or oral cancer; a diagnosis of sensory difficulties affecting the pathways of cranial nerves V & VII, dysosmia, anosmia, dysgeusia, ageusia or hypogeusia; and taking medications that may effect taste.

Participants were recruited at random via the University of Limerick (U.L) events email, which was dispersed to staff and students on campus (Appendix 1). Advertising posters (Appendix 2) were also placed in the Health Science Building where testing was carried out, in the Speech and Language Therapy (S.L.T) clinic. The posters displayed basic information and the inclusion and exclusion criteria.

2.2 Materials

Materials required for this study included white labels, aprons, cotton buds, round paper reinforcement’s (premier depot essentials- 6mm), blue food dye (royal blue icing colour- Wilton Industries), bottled water, plastic cups, a digital camera (Cannon Power Shot- SX30) a laptop, biros, printed questionnaire’s, tea and coffee refreshments.

8 Methodology

2.3. Procedures

Participants expressing interest were provided with an information leaflet (Appendix 3) by a student researcher at the entrance to the clinic, again outlining the exclusion criteria and the procedure allowing them an opportunity to withdraw from the study in accordance with the ethical considerations. Participants were then invited into the S.L.T clinic to carry out 2 test programs; a measurement of fungiform papillae, and a questionnaire judging the intensity and agreeability of a range of sensory and chemesthetic stimuli identified from the literature respectively (Table 2.1). Test stimuli were selected by choosing a range of tastes that best represented the five basic taste qualities, sweet, sour, salty, bitter and umami, as well as the chemesthetic qualities of spicy, fat, cool (menthol), metalicity, carbonated, kokumi and calcium. Additional categories strong regular foods, perfumed, tarte, herb and smoked were also added to ensure depth in the range of tastes chosen. A bland regular foods category was also added to act as a control measure to ensure validity and reliability of participant’s responses. Table 2.1 Taste Stimuli Sweet Salty Sour Bitter Umami Menthol Fudge Seaweed Pure Lemon Dark Strong Goats Mint Herb Maple Syrup Sea Water Juice Chocolate Cheese Minty Hard Meringue Table Salt Natural Yogurt Coffee Soy Sauce Chewing Gum Sugar Vinegar Granules Parmesan Mints Beer Cheese Walnuts Mackerel Spicy Fat Perfumed Herby Smokey Kokumi Black Pepper Cooking Oil Rose Water Raw Thyme Smokey Bacon Gouda Raw Ginger Cream Vanilla Rosemary Smoked Cheese Raw Jalapeno Unsalted Lavender Oil Raw Parsley Salmon Pepper Margarine Cumin Raw Fennel Smoked Teas Chili Powder Strong Regular Bland Strong Metalicity Tarte Carbonated Food Alcohol Raw Garlic Plain Whiskey Kidney Beans Tonic Water Sparkling Raw Onion Porridge Vodka Liver Water Plain Pasta Red Meat Water Cooked Rare Calcium

Non Flavoured Antacids Soda Water

9 Methodology

Before commencing the test programs participants signed a consent form (Appendix 4), after which they received a code number. This code number acted to ensure confidentiality as per ethical guidelines and was applied to both test programs. This code was later used during data input. These test programs were carried out in separate therapy rooms. Researchers were located at each station in order to answer any queries or concerns participants may have had.

Blue Dye Test

A less invasive, simplified version of Bartoshuk’s (1994) taste test procedure was adapted for the purpose of this research to identify (http://www.bbc.co.uk/science). The procedure employed to measure the fungiform papillae density is similar to that described in Shahbake et al. 2005, Zhang et al. 2008, and Fischer et al. 2013. Participant’s tongues were dried using a dry cotton bud, then using another cotton bud, blue food dye was placed on the anterior (left) 1/3 of the tongue. A 6mm diameter circular reinforce was placed over the dye (Figure 2.1).

Figure 2.1 Analysis of blue dye test examples

A digital photo using a zoom function was taken of the stained area. The digital camera has been found to be a valuable tool to estimate taste function using a noninvasive and relatively simple and rapid technique (Shahbake et al. 2005). Table 2.2 outlines identifying criteria applied.

Table 2.2 Taste Category Taster Type Papillae Counted Super Taster = / > 36 Medium Taster 16-35 Non Taster < 15

10 Methodology

Fungiform were identified according to criteria in Miller (1995) and Shahbake et al. (2005). They were readily distinguished from the filiform papillae as the colouring stains the filiform papillae blue, while the fungiform papillae remain unstained (Miller and Reedy 1990). The best image of 3 from each individual was used for counting papillae, which was carried out while participants carried out the second part of the testing; the questionnaire. Photographs were coded in correspondence with the participant code and were stored on one laptop for analysis. Photographs were analyzed by two student researchers to ensure inter-rater reliability, and tasters were categorized accordingly. Where disagreement occurred a third researcher reviewed the photo and agreement was made by majority vote.

Questionnaire The same code was used to code the participant’s questionnaire (Appendix 5), which was filled out in a separate therapy room. Participants were asked to rate 54 individual stimuli for both agreeability and perceived intensity using an adapted hedonic General Labeled Magnitude Scale (GLMS) and a hedonic rating scale.

Hedonic General Labeled Magnitude Scale

Perceived Intensity measures were rated using a General Labelle Magnitude Scale (Figure 2.2). Participants were provided with a 9-point scale containing verbal descriptive estimates, to rate their perceptual opinion of the intensity of the 54 tastes. This approach has been found to be successful in obtaining valid comparisons of the ratings among different respondents in similar studies (Lawless and Heymenn 2010).

How would you describe the intensity or strength of this taste? Tick one box to indicate your opinion on the overall intensity of this taste?

Extremely weak Neither strong & powerful Extremely strong & Insubstantial nor weak and insubstantial & powerful

Figure 2.2 Rating Scales: Perceived Intensity

11 Methodology

Hedonic Scale

Agreeability measures were rated on a hedonic scale (Figure 2.3), which are the most suitable scale to quantify the degree of like or dislike (Kalva et al. 2014).

How much do you like/dislike this taste? Tick one box that best reflects your overall liking of this taste?

Absolutely hate it Neither hate it Absolutely love it Or love it

Figure 2.3 Rating Scales: Agreeability

Participants were informed of their sensory classification (Supertaster, Medium Taster or Non Taster) after they had completed the questionnaire and were provided with some general information about their taster status (Appendix 6). Overall testing took approximately 20-25 minutes and participants were provided with refreshments afterwards.

2.4 Data Analysis

Results were analyzed using IBM SPSS Statistics. Prior to statistical testing, data was tested for normality assumptions. Due to normality test finding of skewed data, quantitative measures of the non- parametric data have been represented by descriptive & inferential tests. Descriptive statistical analyses were performed on the nominal (taster groups) and ordinal (ratings) data to obtain a clear understanding of the population. Measures of central tendency, medians, were computed. Inferential statistical analysis, Spearman’s correlation coefficient, was utilized to assess the strength and direction of the relationship between the variables perceived intensity and agreeability. The Kruskal-Wallis test allows for the comparison of one categorical independent variable with three or more continuous dependent variables (Pallant 2002), and so was used to determine if there was a difference between tasters and their ratings of the 54 taste stimuli. A planned non-parametric post hoc procedure, Mann-Whitney was applied to follow up significance found in the Kruskal- Wallis analyses.

12 Methodology

Factor Analysis, a data reduction technique used to identify groups or cluster of variables (Field 2009), was used to detect structures in the relationships between the perceived intensity and the agreeability of the 54 tastes, by reducing the variables using surrogate factors. This facilitated the naming, differentiation and highlighting of specific phenomena (Pett et al. 2003). The reliability of this scale was reported using Cronbach’s alpha coefficient (α). Fields (2009) and Palland (2002) suggest Cronbach’s α > .7 represents good reliability.

2.5 Ethical Considerations

The University of Limerick, Faculty of Education & Health Science Research Ethics Committee has approved this study. Participants were informed of the proceedings of each stage to ensure that the purpose of testing was clear and unambiguous. Participants could withdraw at any stage if they wished. Anonymity was ensured by the continued use of codes through out the study.

13 Results

3. Results

3.1 Test of Normality

As a prerequisite to statistical testing, the assessment of normality was carried out initially for both Perceived Intensity and Agreeability on all 54 of the taste stimuli, using the Shapiro-Wilk test as it is a more accurate measure of normality (Field 2009). The sample distribution was both significantly different (p < .05) and not significantly different (p > .05). Field (2009) recommends that data be interpreted in conjunction with other findings such as Q-Q plots, histograms and boxplots. Visually, a relatively bell-shaped distribution should suggest normality and similar findings should be reflected in Q-Q plots, with the points adhering closely to the diagonal line suggesting normality, which was not found to be evident in all cases. Additionally the boxplots also identified some potential outliers, again suggesting the assumption of normality was not met. Normal distribution should be indicated by skewness and kurtosis values close to zero. Due to inconsistencies in the data and unequal group sizes non-parametric testing was utilized to report the data. As the data sets are so large size, four randomly chosen examples of all the above criteria have been provided in Appendix 7 and Appendix 8.

3.2 Taster types and strongest reactions.

Descriptive statistics were obtained to summarize and describe the data set of the 108 female participants included in this study and to address the following research questions; Identification of taster types in an Irish population, and determining what the most perceived intense and most perceived agreeable tastes are.

Using the 6mm stained section of the anterior third of the tongue, a count of the papillae was conducted in order to identify taster categories. ‘Tasters’ accounted for 25% of participants as; 5.6 % (n=6) of participants were found to be supertasters (36+ papillae), 19.4% (n=21) medium tasters (16-25 papillae), while 75% (n = 81) were found to be ‘Non- tasters’ (<15 papillae).

14 Results

Perceived Intensity Figure 3.1 shows the ratings of Overall Medians - Perceived Intensity of all 54 stimuli from highest - lowest. Ratings were made on a scale of 1-9: 1 representing “extremely weak and insubstantial” and 9 presenting “extremely strong and powerful”.

10 9 8 7 6 5 4 3 2 1 0 Beer Liver Mints Fudge Sugar Vodka Cream Water Cumin Vanilla Walnut Vinegar Makeral Whiskey Seaweed Table salt Rosemary Red meat Soy sauce Sea water Mint herb Raw Garlic Plain Pasta Cooking oil Raw onion Raw fennel Raw thyme Soda water Raw Ginger Rose Water Smoked tea Raw parsley Tonic water Lavender oil Maple syrup Black Pepper Chilli powder Kidney beans Raw jalapeno Plain porridge Gouda Cheese Smokey Bacon Natural yogurt Dark chocolate Hard merinuge Sparkling water Coﬀee granules Smoked salmon Pure lemon juice Parmesan cheese Miny chewing gum Strong goats cheese Unsalted margerine

Figure 3.1 Overal Medians-Perceived Intensity Non ﬂavoured antacids

Agreeability Descriptive statistics were also obtained to summarize the same finding in relation to participant’s agreeability with each of the stimuli, Figure 3.2 summarizes the overall medians of agreeability on a 9-point scale; 1 representing “absolutely hate it”, and 9 representing “absolutely love it”.

9 8 7 6 5 4 3 2 1 0 Beer Liver Pasta Mints Garlic Fudge Sugar Vodka Cream Water Cumin Ginger Vanilla Walnut Vinegar Makeral Whiskey Seaweed Rosemary Table salt Red meat Soy sauce Sea water Mint herb Cooking oil Raw onion Raw fennel Raw thyme Soda water Rose Water Smoked tea Raw parsley Tonic water Lavender oil Maple syrup Black Pepper Kidney beans Chilli powder Raw jalapeno Plain porridge Gouda Cheese Smokey Bacon Dark chocolate Hard merinuge Natural yogurt Sparkling water Coﬀee granules Smoked salmon Pure lemon juice Parmesan cheese Miny chewing gum Strong goats cheese Unsalted margerine

Non ﬂavoured antacids Figure3.2 Overall Medians- Agreeability

15 Results Table 3.1 – Spearman’s Correlation 3.3 Associations between perceived Coefficient intensity and agreeability Tastes Spearman’s rho Intensity Agreeability

Correlation Coefficient 1.000 .307** As there was no precise assumption Fudge Sig. (2-tailed) . .001 N 108 108 regarding the distribution of the Correlation Coefficient 1.000 -.23* Black Pepper Sig. (2-tailed) . .019 variables testing further non- N 106 105 Correlation Coefficient 1.000 .212* parametric testing was carried out, Plain Pasta Sig. (2-tailed) . .029 N 106 106 accordingly. The Spearman rank Correlation Coefficient 1.000 -.31** Whiskey Sig. (2-tailed) . .001 order correlation coefficients N 107 107 (Spearman’s rho) was performed to Correlation Coefficient 1.000 .295** Mints Sig. (2-tailed) . .002 describe the relationship between N 108 108 Correlation Coefficient 1.000 -.36** the all-54 pairs of continuous Liver Sig. (2-tailed) . .004 N 65 65 variables of perceived intensity and Correlation Coefficient 1.000 -.32** Strong Goats Sig. (2-tailed) . .001 agreeability describing the degree to Cheese N 94 94 Correlation Coefficient 1.000 .265** which the scores are related. A Vanilla Sig. (2-tailed) . .006 N 106 106 correlation coefficient of ±1 is Unsalted Correlation Coefficient 1.000 .265** considered a perfect relationship, the Margarine Sig. (2-tailed) . .009 N 95 95 stronger the correlation, the closer Correlation Coefficient 1.000 -.192* Sparkling Sig. (2-tailed) . .048 the correlation coefficient comes to Water N 107 107 Correlation Coefficient 1.000 -.297** ±1 (Mukaka 2009). If the coefficient Beer Sig. (2-tailed) . .002 N 108 108 is a positive number, the variables Plain Correlation Coefficient 1.000 .303** Porridge Sig. (2-tailed) . .002 are directly related, as the value of N 108 108 Minty Correlation Coefficient 1.000 .267** one variable goes up, the value of the Chewing Sig. (2-tailed) . .005 other also tends to do so. If the Gum N 107 108 Correlation Coefficient 1.000 .241* coefficient is a negative number, the Hard Sig. (2-tailed) . .022 Meringue N 91 91 variables are inversely related, thus Correlation Coefficient 1.000 -.434** Sig. (2-tailed) . .000 as the value of one variable goes up, Sea Water N 103 103 the value of the other tends to go *Correlation is significant at the 0.05 level (2 tailed) **Correlation is significant at the 0.01 level (2 tailed) down (Swinscow 1997). Cohen’s (1998) guidelines were applied to

determine the strength of relationships: (r = ±.10 - ±.29 weak, r = ±.30 - ± .49 medium, r = ± .5- ±1.0 strong).

16 Results

The Spearman’s rho revealed statistically significant relationships (p < .05) between the perceived intensity and the agreeability of 15 of the variables, however there were some positive and some negative correlations found between the variables, Table 3.1. See Table 3.2 and Table 3.3 for a comparison of these tastes to their overall medians.

Table 3.2– Directly Related Stimuli Table 3.3- Inversely Related Stimuli Tastes Perceived Agreeability Tastes Perceived Agreeability Intensity Median Intensity Median Median Median Fudge 6 7 Black pepper 8 6 Plain pasta 3 5 Whiskey 8 4 Mints 8 Liver 8 3 Vanilla 7 7 Strong goats 8 7 cheese Unsalted 5 4 Raw 9 5 margarine jalapeno pepper Plain porridge 5 6 Sparkling 5 5 water Minty 8 7 Beer 7 6 chewing gum Hard 5 7 Seawater 8 2 meringue

3.4 Tasters and tastes Non-parametric testing the Kruskal-Wallis was utilized to determine if a relationship between the taster categories and their perceived intensity and agreeability. Taster type did not significantly affect the perceived intensity or agreeability (p > .05) of all 54taste stimuli. It was concluded that there was no significant relationship between taster types and perceived intensity as p > .05. Similar finding were found when comparing taster type and agreeability for all taste stimuli, with the exception of fudge (p = .004). See Figure 3.3 for a comparison of the relationship between tasters and the perceived intensity and the agreeability of fudge.

17 Results

Figure 3.3 -Tasters and Fudge

A review of the box plots indicates that the medians of Supertaster and Medium Tasters are similar, however the median of the Non-taster group appears higher. As this conclusion is subjective it was followed up with a post hoc test the Mann Whitney. In order to ensure no build up of a type 1 error occurred a Bonferroni Correction was applied. A type 1 error is the rejection of the null hypothesis when it is actually true (Pallant 2009). To achieve this, the alpha level p = .05 was divided by the amount of tests that were intended to be carried out, which in this case was 3: super taster and non-taster, supertaster and medium taster, medium and non-taster. For the purpose of this test P = 0.0167 (5/3). Both Super taster and medium tests, and super taster and non-taster tests produced values above p > 0.0167, so it was concluded that these were not significant. Findings of the mean rank (Figure 3.4) and p = .002, mainly reflect that a non-taster is more likely have greater agreeability for fudge (Figure 3.5)

Figure 3.4 Mann Whitney Mean Ranking Figure 3.5 Mann Whitney Significance

Mean Groups Sig Bonferroni N Rank Correction Agreeability Super taster 6 37.00 Super v .075 P = .0167 Fudge Medium taster 21 37.69 Medium Non-taster 81 60.15 Super v .997 P = .0167 Total 108 Non Non v .002 P = .0167 Medium

18 Results

3.5 Identification of tastes for future development

A principle component analysis was conducted on the 54 items of perceived intensity and agreeability, using this method: generation of the items, extraction of the initial factors, orthogonal rotation (varimax) and interpretation (Pett et al. 2003). An initial analysis was run to obtain eigenvalues for each component of data for both perceived intensity and agreeability. The scree plot for both perceived intensity and agreeability were slightly ambiguous (Figure 3.6 and Figure 3.7) and shows inflexions that would justify retaining components 3 and 5.

Figure 3.6 Scree Plot- Perceived Intensity Figure 3.7 Scree plot -Agreeability

Given the sample size and the convergence of the scree plot it was decided to retain 5 factors. Only items above .5, the lowest acceptable limit (Field 2009) were accepted. A full table of factor loadings is provided in Appendix 9. Table 3.4 shows the factor loads of the 54 stimuli of perceived intensity. Factors were labeled to interpret the factor dimensions.

19 Results

Table 3.4 Factor Analysis Loadings of Perceived Intensity 1.Powerful Intense 2.Common place 3.Deeply Intense/ 4.Distinct Irregular 5.Dissimilar foods Irregular Taste Loading Taste Loading Taste Loading Taste Loading Taste Loading Tonic .546 Raw .654 Mints .575 Smokey .622 Soy .662 water garlic bacon sauce Raw .788 Raw .699 Seaweed .601 Gouda .539 Plain .564 ginger onion cheese pasta Dark .727 Pure .826 Liver .593 Red .593 Raw .593 chocolate lemon meat fennel juice cooked rare Parmesan .520 Maple .607 Smoked .528 Cream .603 Plain .656 cheese syrup teas porridge Mint .675 Non .545 Rosemary .730 Walnuts .635 herb flavoured antacids Chili .754 Vodka .743 Lavender .539 Hard .747 powder oil meringue Mackerel .771 Table salt .609 Raw .660 parsley Smoked .599 Vinegar .715 salmon Sea water .629 Coffee .724 granules Whiskey .513

Cronbachs alpha coefficient was used to measures the overall reliability of the degree to which items grouped together on extracted factors to check reliability. Cronbachs α of .7 to .8 is an indication of overall good reliability (Fields 2009). Using this method group 1 (powerful intense), group 2 (common place foods) and groups 3 (deeply intense/irregular) all had high reliability (Cronbachs α > .7). However group 4 (distinct irregular) and group 5 (dissimilar) had relatively low reliability low reliability (Cronbachs α < .7), limiting their potential for use in dysphagia therapy (Table 3.5).

Table 3.5 Reliability of Perceived Intensity score Group Cronbachs α Powerful intense .811 Common place foods .779 Deeply intense/irregular .808 Distinct irregular .649 Dissimilar .564

20 Results

Similar rules were applied to the Agreeability of stimuli. A full table of factor loadings is available in Appendix 10. Table 3.6 demonstrates how items ( r > .5) are grouped together in the 5 retained factors..

Table 3.6 Factor Analysis Loadings of Agreeability Again Cronbach’s alpha coefficient 1.Intensifying 2.Sweet desserts 4.Fragrant Taste Loading Taste Loading Taste Loading was used to measure reliability of Raw .775 Cream .704 Smoked .829 the grouping. In this data set only garlic tea Black .665 Dark .563 Lavender .646 one group was reliable over all: pepper Chocolate oil Soy sauce .629 Coffee .613 group 1 (Cronbach’s α = .865), granules 5.Sharply distinct Raw .775 Sugar .854 Taste Loading indicating excellent reliability. All thyme other groups were found to be Raw .799 Whiskey .649 onion 3.Mineral relatively low in reliability, see Raw .782 Taste Loading Vodka .708 ginger Table 3.7. Gouda .682 Walnuts .772 Smoked .727 cheese salmon Pure .649 Sparkling .763 Table 3.7 Reliability of lemon Water Agreeability score juice Group Cronbachs α Cumin .598 Soda .722 Intensifying .865 water Sweet dessert .375 Vanilla .688 Rosemary .793 Mineral .594 Table salt .556 Fragrant .492 Vinegar .570 Sharply Distinct .404 Parmesan .647 cheese

Raw .667 parsley Mint .733 herb

21 Discussion

4.Discussion

4.1 Principle findings.

The main objective of this study was to gain a preliminary data that could be used in modulating the further development of swallow assessment and therapy tools, and determining if there is a direct link between the density of papillae on the tongue and the perception of intensity and the agreeability of taste stimuli that could also be of benefit in further dysphagia research.

Division of the Irish population in terms of taster status Counting of the fungiform papillae following the blue dye test separated the participants in to super taster (6%), medium tasters (19%) and non-tasters (75%). These findings are much lower than anticipated, as Bartoshuk et al. (1994) suggests that the population should be divided at 25% non-tasters, 25% medium tasters and 50% medium tasters. Women only were used for this study as it had previously been hypothesized that women were statistically more likely to be supertasters than men (Bartoshuk et al.1994).

However it is important to consider that previous studies have been carried out on a wide range of different cultures and ethnic groups, and given cultural variation on availability and preparation of food, sensitivity to certain foods may be less in some cultures compared to others, making it difficult to draw comparisons of this study to others. It has been found that super-tasters are in fact more likely to be of African, Asian, or South American decent (Bartoshuk et al. 1994). Comparing a typical diet of these cultures to that of a typical Irish diet, it is suggestive that the range and variety of tastes are much more limited in the Irish population.

Is this classification useful in assessment or therapy for dysphagia? Although the fungiform papillae are relatively stable anatomical structures and may prove to be the most stable measure of genetic inheritance of taste, taste sensations are dependent on several other factors and the correlation between the number of fungiform papillae and taste function will never be perfect. Not only must the integrity of the

22 Discussion fungiform papillae and the taste buds within the fungiform papillae be intact, the nerves that carry appropriate sensory information, from the papillae to the brain, must also remain intact.

Taking into consideration the pathologies and neurological injuries that are likely to present in the dysphagic populations it is difficult to conclude that taster status could be a beneficial tool in dysphagic assessment and therapy. On one hand, as previously studies have shown the excitement of specific neural pathways via the sensation of intense stimuli can lead to a faster stronger swallow reflex (Logemann et al. 1995; Cola et al. 2013; Pelletier and Lawless 2003), thus an awareness of the sensitivity to particular tastes, through the identification of taster status, may be of some benefit.

On the other hand, an injury or insult to the innervation of the chorda tympani, or the trigeminal cranial nerve may alter individual’s sense of taste physiologically, but anatomically the structures of fungiform papillae will remain the same. The identification of a person as a super, medium or non-taster may in fact be deemed irrelevant in its use for dysphagia population. However imperfect the findings might be in relation to dysphagia, the counting of papillae can still suffice to determine the perceived intensities across individuals, and this accurate measurement is still fundamental to other scientific research.

The relationship between taster categories and tastes This study has shown that using a simplified blue dye test to determine taster status, and LMS and hedonic 9 point scales, did not show any evident or clear relationships between the tasters and the their perceived intensity (p > .05). It was hypothesized that supertasters would have had significantly higher responses to perceived intensity particular stimuli such as sour, sweet and carbonated, in support of previous findings of these stimuli (Bülow et al. 2003; Miura et al. 2009; Logemann et al.1995; Cola et al. 2010; Pelletier and Lawless 2003), however it was clear that supertaster did not experience any heightening perception of any particular taste or taste category. Across the three groups of tasters, the perceived intensity of sweet, sour and carbonated tastes received similar ratings, with no significance difference found in any of the three groups. Although this was unexpected, it does suggest

23 Discussion a unified response among taster types suggesting a preference among a more generalized population, which will be useful in the application of type assessment and therapy tools.

Strongest reactions of perceived intensity and agreeability Overall 36 out of the 54 taste stimuli were perceived as high in intensity (a rating of 7 or more) and represented a range of the taste categories: sweet, sour, spicy, bitter, umami, minty, strong alcohol, metalicity, salty, smoky, kokumi, perfumed and herby. Neutral tastes (plain porridge, plain pasta, water) ratings of perceived intensity were low, reflecting a lack of or lowered sense of taste for those stimuli, as was to be expected.

A much lower of overall tastes (15/54) were identified as high in agreeability, of which the taste groups included sweet, umami, bitter, perfumed, mint, smoked and, unexpectedly, water was rated one the overall most agreeable taste. Mint and Sweet tastes were dominant in this category accounting for 7 of the 15 tastes (4 sweet and 3 mint). It was noted that a significant relationship was found between one taster type and one sweet taste, fudge (p = .004). Upon further post hoc testing, it was discovered the relationship was only significant between non-tasters and fudge. This appears to be in support of Bartoshuk’s findings (1994), that suggest supertasters perceive greater sweetness from sucrose and avoid such tastes, while non-tasters have no such aversion. Other studies have gone as far to suggest that older and younger female super tasters are in fact slimmer then non-tasters as a result (Lachina et al. 1995; Dabrila et al.1995). Similar findings were reported by Duffy et al. (1996) in both men and women supertasters.

Relationship between the perceived intensity and agreeability Only 15 of the tastes were found to have a significant relationship (p < .05) in terms of perceived intensity and agreeability. However, only 8 tastes are support of positive significant relationships: fudge, plain pasta, mints, vanilla, unsalted margarine, plain porridge, minty chewing gum, hard meringue. Again sweet and minty tastes are dominant in this grouping, receiving slightly higher median scores. Removing the bland control tastes (plain porridge and plain pasta) and unsalted margarine, as it lacks in intensive flavor, the categories left are sweet (fudge, hard meringue) mint (mints, minty chewing gum) and perfumed (vanilla).

24 Discussion

While tastes such as sweet (Ding et al. 2003; Pelletier et al. 2003) and mint (Ebhiara et al. 2006) have been previously investigated, they are still both under researched, undeveloped and need critical consideration in the development of this research. Both are tastes can be easily accessed and easily administered. Mint in particular has already been identified as a key agent in the reduction of swallowing delays as well the prevention of aspiration/penetration in the elderly (Ebihara et al. 2006). Although liquid boluses are used most frequently, a sweet or mint bolus taste that could allow for adequate stimulation of the taste buds while reflecting normal eating habits would be ideal. The findings of this study would be in support of further developing mint and sweet as an assessment or therapy tool following the correlated and significant findings of perceived intensity and agreeability.

Vanilla, or perfumed tastes are understandably under-researched, and findings from this study suggest that dysphagia research take a step away from using the five typical taste categories and consider broadening the spectrum to other available tastes that are preferred.

Stronger more intense tastes: whiskey, liver, sparkling water, and seawater were inversely related, suggesting that the higher the perceived intensity these tastes were rated the lower the agreeability ratings were. However beer, black pepper and strong goats cheese were also found to be inversely related but on closer examination, they were found to have higher overall medians (see Table 3.3) of agreeability then the others, suggesting the intensity of these taste types is slightly more preferred, although still statistically insignificant. Sparkling water had also been cited in the literature as beneficial in the reduction of aspiration in dysphagic patients (Bülow et al. 2003), and Sdravou et al. (2012) reported the majority of participants had found the bolus palatable, however it was not the case in this study.

25 Discussion

Taste groups Following tests of reliability using Cronbach’s alpha coefficient, factor analysis also identified five groups from perceived intensity data and just one group agreeability, all of which are believed to have common underlying characteristics that grouped the tastes together. The author has identified underlying structures as elements that best describe how the groups best fit together. It is important to note that there are few similarities between the perceived intensity groups of the agreeability. Considering the lack of research into the palatability of a bolus and its influence on taste (Schwartz et al. 2009) it might be of benefit to consider these taste groups in the development of dysphagia tools. Tastes that are more agreeable to individuals should, hypothetically, be more successful in therapy, with higher rates of compliance expected, and thus deserve further development in dysphagia research.

It is clear that the perceived intensity factors loaded to group one are powerful and intense foods that may be considered an acquired taste, while factor that are load onto groups two and four are foods that may be commonly found in households and used on a regular basis, but group four could be argued to be more distinctive in taste. Group three are representative of more intense foods some of which are more unusual. Again, Group five are foods that could be regularly found in a typical diet but other than some bland tastes, overall they are quite dissimilar. It could be argued they are slightly blander it taste.

In contrast, factors of agreeability that load onto Group one appear to have more common underlying structures as they common tastes that would normally be added to a meal to enhance the flavor. This category are of particular relevance as they are tastes, if found successful in improving dysphagic symptoms, that would allow a person to continue, as closely to as permissible, to normal eating habits. They are foods that are not only familiar and readily available, they could be adapted to less invasive methods such as lozenges (Ebhiara et al. 2006), and could be cost effective.

26 Discussion

4.2 Implications This study has been successful in identifying areas that can implicate future dysphagia research, assessment and therapy. Not only has it identified tastes that are highly correlated in terms of perceived intensity, necessary for the excitement of the appropriate neural pathways, but also in terms of agreeability. A lack of agreeability or palatability has previously been identified in the literature as an issue with current dysphagia therapy approaches (Logemann et al. 1995; Pelletier and Lawless 2003; Steele and Miller 2010), and subsequently has so far limited the use of sensory and chemesthetic stimuli. This study also lends itself to consideration of more detailed aspects of the presentation of dysphagia, and further examination of the various sensory pathways, perception of taste and the physiological manner by which sensory messages are received. Knowledge of how different tastes provoke different reactions anatomically and physiologically will be of great benefit in the development of dysphagia research. Using specific tastes to excite the damaged pathway would allow for the use of a more individualized therapy approach. For example using tastes such as salty or sweet to heighten the activation of the facial nerve (Ding et al. 2003), or the use of sour or bitter stimuli to stimulate the glossopharyngeal (Frank and Smith 1991). Additionally this study highlights the need for dysphagia researcher to widen the parameters of tastes and chemesthetic stimuli from the five classical tastes of sweet, salty, sour, bitter and umami, by its identification of preferred tastes such as mint and vanilla.

4.3 Limitations The researcher noted some limitations to this study. The lack of probability sampling limits the study from making generalizations about the population and the data collection, and needs to be considered in the further development of this study. Considering the unexpectedly low findings of supertasters in this study, men should be considered as participants in the follow up studies to aid further generalization. The identification of taster types was simplified in comparison to other studies and this method may need to be more scientific and standardized in future research, such as the PROP testing method used in previous research (Fischer et al. 2013, Bartoshuk et al. 1994, Shahbake et al. 2005). The groups identified in Factor Analysis are subjective to the researchers opinion, thus are open to others interpretations.

27 Discussion

4.4 Summary Findings of this study suggest that the identification of taster types has not yet been found to be of significant value in dysphagia therapy. It does however suggest a unified response among a selected Irish population that is of benefit to future research. It has been successful in identifying individual taste categories sweet, mint and perfumed that are highly correlated in terms of perceived intensity and agreeability, and require further analysis in follow studies. It has also provided a gainful insight into groups of foods that relate to each other that also can be of benefit in future research. These tastes are of particular interest as some are those already used to intensify and enhance other tastes, are readily available, cost effective, familiar and easy to administer.

4.5 Conclusions Further research is required into understanding how genetics and chemesthesis play a role in swallow physiology, particularly with the dysphagic populations. As knowledge of the complex mix of factors that influence swallowing physiology, and how and why some people display more positive responses to some taste and chemesthetic stimuli over others is developed, it is hoped that clinicians eventually will be able to predict and prescribe certain tastes or stimuli to compensate for oro-pharyngeal dysphagia in individuals with different taste genetics. This study has identified some potentially useful sensory and chemesthetic stimuli that can aid further development in this area.

28 Reference List

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33. Logemann, J.A., Pauloski, B.R., Colangelo, L., Lazarus, C., Fujui, M & Karhilas, P.J. (1995) ‘Effects of a sour bolus on oropharyngeal swallowing measures in patients with neurogenic dysphagia.’ Journal of Speech , Language and Hearing Research, 38 (3), 556-563. 34. McCurtin, A. (2012). Deconstructing Clinical Practice and Searching for Scientific Foundations: Examining Decision-making Scaffolds Underpinning Intervention Choices by Speech and :Language Therapists. Dept of Sports, Tourism and the Outdoors. Preston, UK., University of Central Lancashire. PhD thesis 35. Methven, L., Allen, V.J., Withers,C.A. and Gosney, M.A. (2012) ‘Ageing & Taste’, Proceedings of the Nutrition Society, 71 (4),556-565 36. Miller, I.J. and Reedy, F.E. (1990) ‘Qualification of fungiform papillae and taste pores in living human subjects’, Chemical Senses, 15,281-294. 37. Miura, Y., Morita, Y., Koizumi, H. and Shingai, T. (2009) ‘Effects of taste solutions, carbonation, and cold stimulus on the power frequency content of swallowing submental surface electromyography’, Chemical Senses, 16, 146-150. 38. Mukaka, M. (2012) ‘A guide to appropriate use of the corellation coefficient in medical research’, Malawi Medical Journal, 24 (3), 69-71. 39. Palland, J. (2002) SPSS Survival Manual; A step by stpe guide to data analysis using SPSS for Windows (Version 12)., Australia: Allen & Unwin. 40. Palmer, P.M., Jaffe, D.M., McCulloch, T.M., Finnegan, E.M., Van Daele, D. and Luschei, E.S. (2008) ‘Quantitative Contributions of the Muscles of the Tongue, Floor- of-Mouth, Jaw, and Velum to Tongue-to-Palate Pressure Generation’, Journal of Speech, Language, And Hearing Research, 51, 828-835. 41. Pelletier, C.A and Steele C.M (2014) ‘Influence of perceived taste intetnosty of chemesthetic stimuli on swallowing papameters given age and genetic taste differences in healthy adult women’, Journal of Speech, Language and Hearing Research, 57 (1), 46-56. 42. Pelletier, C.A. & Dhanaraj, G.E. (2006) ‘The effect of taste and palatability on lingual swallowing pressure’, Dysphagia, 21 (2) 121-128. 43. Pelletier, C.A. and Lawless, H.T. (2003) ‘Effect of citrus acid and citrus acid-sucrose mixtures on swallowing in neurogenic oropharyngeal dysphagia’, Dysphagia, 18, 231- 241.

32 Reference List

44. Pett, M.A., Lackey, N.R., Sullivan, J.J. (2003) Making Sense of Factor Analysis: the use of facto analysis for instrument development in Health Care Research, USA: SAGE Publishing, 45. Prescott, J., Ripandelli, N. and Wakeling, I. (2001) ‘Binary taste mixture and interactions in PROP non tasters, medium tasters and supertasters’, Chemical Senses, 29, 993-1003. 46. Rofes, L., Arreola,V., Martin, A. and Clavé, P (2012) ‘Natural capsaicinoids improve swallow response in older patients with oropharyngeal dysphagia’, Gut, 62, 1280- 1287. 47. Schwartz, C., Issanchous, S. and Nicklaus, S. (2009) ‘Developmental changes in the acceptance of the five basic tastes in the first years of life’, British Journal of Nutrition, 102, 1375-1385. 48. Sciortino, K.F., Liss, J.M., Gerritsen,K.G.M and Katz, R.C. (2003) ‘Effects of mechanical, cold, gustatory and combined stimulation to the human anterior faucial pillars’, Dysphagia, 18, 16-26. 49. Sdravou, K., Walshe, M. and Dagdilelis, L. (2012) ‘ Effects of carbonated liquids on oropharyngeal swallowing measures in people with neurogenic dysphagia’, Dysphagia, 27,240-250. 50. Shahbake, M., Hutchinson,I., Laing, D.G. and Jinks, A.L. (2005) ‘Rapid quantitative assessment of fungiform papillae density in the human tongue’, Brain Research, 1052(2),196-201. 51. Smith, D.V. and Margolskee, R.F. (2001) ‘Making sense of taste’, Science America, 281, 32-39. 52. Steele, C.M. & Miller, A.J. (2010) ‘Sensory input pathways and mechanisms in swallowing: a review’, Dysphagia, 25, 323-333. 53. Zhang, G.H., Zhang, H.J., Wang, X.F., Zhan, Y.H, Deng, S.P. & Qin, Y.M. (2008) ‘The relationship between fungiform papillae density and detection threshold for sucrose in the young males’, Chemical Senses, 34 (1), 93-99.

Appendices

Appendix 1

Are you a supertaster? Maybe a non-taster? Are you interested in finding out? We can tell you! And you can help us by telling us what you think about different tastes.

If you are female, aged between 18-50 years, a non-smoker of at least 6 months duration, don’t have allergies or a history of ear nose and throat problems, don’t have diagnosed sensory problems related to smell and taste, are not on medications which affect your sense of taste and smell, don’t have gum disease and don’t have a cough, cold or any respiratory infection on the day of in question, we would appreciate your help in our study on taste….

We will ask you a number of questions about your taste preferences, place blue dye on the tip of your tongue and take a photo of the dye! Then, while we check out your photo you can have coffee and a biscuit.

Interested? Please come to the Speech & Language Therapy Clinic in the Health Sciences Building (across the Living Bridge) anytime on ______day, the _th of January.

This study has received ethical approval from the University of Limerick Research Ethics Committee. If you have concerns regarding this study, please contact: Chairman, Education and Health Sciences, Research Ethics Committee, EHS Faculty Office, University of Limerick, Tel (061) 234101 Email : [email protected]

Appendix 2

WANTED!

FEMALE VOLUNTEERS!

ARE YOU A SUPERTASTER OR A NON-TASTER?

Interested? Please come to the Speech & Language Therapy Clinic in the Health Sciences Building (across the Living Bridge) Anytime between 10am and 5pm on Monday 3rd/Tuesday 4th of February. Just give us 10 minutes of your time, answer questions about your taste preferences. We’ll put blue food dye on your tongue and you can find out!

REWARD TEA, COFFEE AND BISCUITS This research study has received Ethics approval from the Education and Health Sciences Research Ethics Committee (2013_10_08_ EHS). If you have any concerns about this study and wish to contact someone independent you may contact: Chairman, Education and Health Sciences Research Ethics Committee, EHS Faculty Office, University of Limerick, Tel 00 353 (061) 234101

Appendix 3

INFORMATION SHEET The name of this study is….. ‘The identification of perceived intensity and agreeability of sensory and chemesthetic properties of selected taste stimuli among a selected non- dysphagic population’.

The purpose of this information sheet is to give you the information about our study so you can make an informed choice to participate or not. To participate you must be…………… Female Aged between 18-50 years A non-smoker of at least 6 months duration You must not……………. Have allergies Have a history of ear nose and throat problems including oral surgery Have diagnosed sensory problems Have gum disease related to smell and taste Be on medications which affect your Have a cough, cold or any respiratory sense of taste and smell infection today

We want to find out about what you think about various tastes. We also want to count the number of fungiform papillae on the tip of your tongue to see if you are a supertaster, average taste or what’s called a non-taster. This will help us understand if your tastes preferences are related to the number of papillae on your tongue. We will ask you to rate a number of tastes in one room, and then we will take you to another room to place some blue food dye on the tip of your tongue. We will take a photo so we can count the papillae. Then you can wipe your tongue or take a drink of water to cleanse your tongue. Have a cup of coffee if you want and while you do that we can count your papillae and tell you which taste category you are in. If you are happy to participate in our study, please sign the consent form, and then we can start.

Appendix 4

Consent Form

I ______(please print name) hereby give my consent to take part in the above study. I understand my data will be anonymized. I do not have any known allergies I am aware of the potential risks and understand I can opt of the study at any stage.

Signed:______

Date:______

This survey has received ethical approval from the University of Limerick Research Ethics Committee. If you have concerns regarding this study, please contact: Chairman, Education and Health Sciences, Research Ethics Committee, EHS Faculty Office, University of Limerick, Tel (061) 234101 Email : [email protected]

Appendix 5

‘The identification of perceived intensity and agreeability of sensory and chemesthetic properties of selected taste stimuli among a selected non-dysphagic population’. Participant code:

Item Ratings 1 How would you describe the intensity or strength of this taste? Tick one box to indicate your Fudge opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 2 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw garlic opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 3 How would you describe the intensity or strength of this taste? Tick one box to indicate your Black opinion on the overall intensity of this taste. pepper □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 4 How would you describe the intensity or strength of this taste? Tick one box to indicate your Cooking opinion on the overall intensity of this taste. oil □ □ □ □ □ □ □

□ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 5 How would you describe the intensity or strength of this taste? Tick one box to indicate your Tonic opinion on the overall intensity of this taste. water □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 6 How would you describe the intensity or strength of this taste? Tick one box to indicate your Soy sauce opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 7 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw opinion on the overall intensity of this taste. thyme □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 8 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw onion opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial

& powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

9 How would you describe the intensity or strength of this taste? Tick one box to indicate your Smoky opinion on the overall intensity of this taste. bacon □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 10 How would you describe the intensity or strength of this taste? Tick one box to indicate your Plain opinion on the overall intensity of this taste. pasta □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 11 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw opinion on the overall intensity of this taste. ginger □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 12 How would you describe the intensity or strength of this taste? Tick one box to indicate your Gouda opinion on the overall intensity of this taste. cheese □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste?

□ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 13 How would you describe the intensity or strength of this taste? Tick one box to indicate your Rosewater opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful

How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 14 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw opinion on the overall intensity of this taste. fennel □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 15 How would you describe the intensity or strength of this taste? Tick one box to indicate your Whiskey opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 16 How would you describe the intensity or strength of this taste? Tick one box to indicate your Mints opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □

□ □ Absolutely hate it Neither hate it Absolutely love it nor love it 17 How would you describe the intensity or strength of this taste? Tick one box to indicate your Red meat opinion on the overall intensity of this taste. cooked rare □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

18 How would you describe the intensity or strength of this taste? Tick one box to indicate your Cream opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 19 How would you describe the intensity or strength of this taste? Tick one box to indicate your Pure opinion on the overall intensity of this taste. lemon juice □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 20 How would you describe the intensity or strength of this taste? Tick one box to indicate your Maple opinion on the overall intensity of this taste. syrup □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it

Absolutely love it nor love it 21 How would you describe the intensity or strength of this taste? Tick one box to indicate your Seaweed opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 22 How would you describe the intensity or strength of this taste? Tick one box to indicate your Dark opinion on the overall intensity of this taste. chocolate □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful

How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 23 How would you describe the intensity or strength of this taste? Tick one box to indicate your Walnuts opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 24 How would you describe the intensity or strength of this taste? Tick one box to indicate your Liver opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 25 How would you describe the intensity or strength of this taste? Tick one box to indicate your 44

Strong opinion on the overall intensity of this taste. goats cheese □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 26 How would you describe the intensity or strength of this taste? Tick one box to indicate your Cumin opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

27 How would you describe the intensity or strength of this taste? Tick one box to indicate your Smoked opinion on the overall intensity of this taste. teas e.g. lapsang □ □ □ □ □ □ □ suchong □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 28 How would you describe the intensity or strength of this taste? Tick one box to indicate your Water opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 29 How would you describe the intensity or strength of this taste? Tick one box to indicate your Vanilla opinion on the overall intensity of this taste. □ □ □ □ □ □ □

Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 34 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw opinion on the overall intensity of this taste. jalapeno pepper □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 35 How would you describe the intensity or strength of this taste? Tick one box to indicate your Natural opinion on the overall intensity of this taste. yoghurt □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

36 How would you describe the intensity or strength of this taste? Tick one box to indicate your Sparkling opinion on the overall intensity of this taste. water □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 37 How would you describe the intensity or strength of this taste? Tick one box to indicate your Beer opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful

How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 38 How would you describe the intensity or strength of this taste? Tick one box to indicate your Plain opinion on the overall intensity of this taste. porridge □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 39 How would you describe the intensity or strength of this taste? Tick one box to indicate your Table salt opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 40 How would you describe the intensity or strength of this taste? Tick one box to indicate your Vinegar opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful

□ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 42 How would you describe the intensity or strength of this taste? Tick one box to indicate your Coffee opinion on the overall intensity of this taste. granules □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 43 How would you describe the intensity or strength of this taste? Tick one box to indicate your Lavender opinion on the overall intensity of this taste. oil □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 44 How would you describe the intensity or strength of this taste? Tick one box to indicate your Raw opinion on the overall intensity of this taste. parsley □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

45 How would you describe the intensity or strength of this taste? Tick one box to indicate your The herb opinion on the overall intensity of this taste. mint □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □

□ □ Absolutely hate it Neither hate it Absolutely love it nor love it 46 How would you describe the intensity or strength of this taste? Tick one box to indicate your Kidney opinion on the overall intensity of this taste. beans □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 47 How would you describe the intensity or strength of this taste? Tick one box to indicate your Chilli opinion on the overall intensity of this taste. powder □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 48 How would you describe the intensity or strength of this taste? Tick one box to indicate your Mackerel opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 49 How would you describe the intensity or strength of this taste? Tick one box to indicate your Smoked opinion on the overall intensity of this taste. salmon □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful

How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it

Absolutely love it nor love it 50 How would you describe the intensity or strength of this taste? Tick one box to indicate your Soda opinion on the overall intensity of this taste. water □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 51 How would you describe the intensity or strength of this taste? Tick one box to indicate your Minty opinion on the overall intensity of this taste. chewing gum e.g. □ □ □ □ □ □ □ airwaves □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 52 How would you describe the intensity or strength of this taste? Tick one box to indicate your Hard opinion on the overall intensity of this taste. merengue □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it 53 How would you describe the intensity or strength of this taste? Tick one box to indicate your Seawater opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

54 How would you describe the intensity or strength of this taste? Tick one box to indicate your 51

Sugar opinion on the overall intensity of this taste. □ □ □ □ □ □ □ □ □ Extremely weak Neither strong & powerful Extremely strong & insubstantial nor weak & insubstantial & powerful How much do you like/dislike this taste? Tick one box which best reflects your overall liking of this taste? □ □ □ □ □ □ □ □ □ Absolutely hate it Neither hate it Absolutely love it nor love it

Appendix 6

Thank you for participating in our study!!!!

You are a : Supertaster ☐ Medium Taster Non-Taster What does this mean? Whether you're a non-taster or a supertaster or somewhere in-between depends on your sensitivity to a bitter chemical called 6-n-propylthiouracil (PROP). Non-tasters can't taste the bitterness of PROP at all. Medium tasters sense the bitterness but don’t mind it, while supertasters find the taste of PROP revolting.

Tasters can also be identified by the amount of papillae visible on the tongue. We used blue dye to highlight these papillae.

Supertasters- 25% of people Supertasters experience the five basic tastes, especially bitter foods, with greater intensity and report PROP to taste very strong, even revolting.

As a Supertaster you have more taste buds than the average person, we found this out by counting the amount of papillae on your tongue. Papillae are tiny structures on your tongue that contain your taste buds.

All these extra taste buds tend to make supertasters hyper sensitive to tastes textures, due to the increased intensity of any given taste they are detecting. Researchers estimate the supertasters experience flavors about three times stronger than the average taster.

Because of this, supertasters tend to hate green vegetables, grapefruit juice, certain alcoholic beverages, coffee, green tea, soy based products and overly sweet things.

Supertasters also tend to feel more pain or irritation on their tongue from things like spicy foods or carbonated water and perceive the creaminess of high-fat foods more strongly than medium- or non-tasters. Supertasters also tend to prefer salty foods, possibly because it counteracts the bitterness

Medium Tasters- 50% of people Medium tasters can detect PROP, but don’t have a strong aversion to its bitterness, while supertasters find the taste of PROP revolting.

Medium tasters have fewer taste buds than Supertasters, but more than Non -tasters. Super tasters are hyper sensitive to some tastes and flavors, while non-tasters do not detect all tastes such as bitter or sweet. Non- and medium-tasters are likely to try news foods, and can reap the benefits of a widely varied diet.

Non Tasters- 25% of people Contrary to what the name implies, non-tasters don't actually lack a sense of taste—it's just that their sense is dampened in comparison with the other groups, especially when it comes to bitter and sweet tastes. For example, people in this group don't taste the bitter aftertaste of saccharine (a sweet tasting synthetic replacement for sugar) that many medium- and supertasters complain about.

Appendix7

Tests of normality - Shapiro-Wilk Intensity Agreeability Taste Sig. Sig. Fudge .110 .023 Raw garlic .001 .082 Black pepper .000 .020 Cooking oil .075 .010 Tonic water .404 .013 Soy sauce .010 .040 Raw thyme .002 .357 Raw onion .000 .202 Smokey bacon .059 .001 Plain pasta .002 .004 Raw ginger .000 .035 Gouda cheese .050 .048 Rose water .081 .008 Raw fennel .017 .089 Whiskey .000 .016 Mints .004 .004 Red meat cooked rare .004 .005 Cream .394 .040 Pure lemon juice .000 .047 Maple Syrup .039 .307 Seaweed .040 .300 Dark chocolate .001 .038 Walnuts .051 .395 Liver .019 .000 Strong goats cheese .000 .000 Cumin .003 .168 Smoked teas .041 .020 Water .000 .001 Vanilla .103 .005 Rosemary .038 .057 Non-flavoured antacids .170 .044 Vodka .000 .104 Unsalted margarine .021 .026 Raw jalapeno pepper .000 .238 Natural yoghurt .059 .461 Sparkling water .050 .046 Beer .000 .031 Plain porridge .011 .091 Table salt .006 .200 Vinegar .000 .262 Parmesan cheese .022 .000 Coffee granules .002 .002 Lavender oil .008 .049 Raw parsley .067 .033 Mint herb .009 .001 Kidney beans .003 .076 Chilli powder .000 .087 Mackerel .004 .010 Smoked salmon .042 .000 Soda water .260 .304 Minty chewing gum .000 .006 Hard meringue .014 .005 Seawater .000 .001 Sugar .112 .008

Appendix 8

Q-Q plots, histograms, boxplots, skewness and kurtosis.

Skewness and Kurtosis Perceived Intensity Agreeability Raw Ginger Coffee Granules Black Pepper Table Salt Skewness -1.405 -.461 -.780 -.409 Kurtosis 2.4.14 .887 .099 -.698

Appendix 9

Factor Loadings; Component Matrix- Perceived Intensity Taste 1 2 3 4 5 Fudge .140 .357 .111 .155 .014 Raw garlic .131 .654 -.083 -.226 .024 Black pepper -.329 .388 .154 -.311 -.561 Cooking oil .463 .024 -.256 -.042 .099 Tonic water .546 -.053 -.038 -.105 .002 Soy sauce .254 .294 .228 -.181 .662 Raw thyme .440 .181 .185 -.084 .462 Raw onion -.121 .699 .139 .111 .041 Smokey bacon -.271 .247 .082 .622 -.115 Plain pasta -.382 .219 -.157 .110 .564 Raw ginger .788 .129 .058 .294 -.084 Gouda cheese .139 -.002 -.056 .539 .066 Rose water -.014 .322 .110 .082 .395 Raw fennel -.088 .247 .257 .232 .593 Whiskey .027 .513 .146 .271 -.118 Mints .148 .427 .575 -.145 -.292 Red meat cooked rare -.139 .110 .347 .593 .194 Cream .272 .190 -.336 .603 .182 Pure lemon juice .069 .826 .161 .033 .109 Maple syrup .415 .607 -.200 .252 .348 Sea weed -.195 .091 .601 -.163 .454 Dark Chocolate .727 .233 .004 -.016 .274 Walnuts -.128 -.009 .049 .635 .213 Liver .087 -.201 .593 .439 -.235 Strong goats cheese -.195 .156 .213 .400 .460 Cumin .400 -.055 .366 .467 .412 Smoked teas .323 -.095 .528 .260 .346 Water .223 -.311 .054 -.384 .415 Vanilla .419 .290 .363 .389 .075 Rosemary .329 .195 .730 .209 .045 Non flavoured antacids -.085 .545 -.124 -.263 .284 Vodka -.028 .743 .065 .006 .050 Unsalted margarine .314 -.027 -.549 .374 .070 Raw jalapeno pepper .163 .448 .427 .097 -.176 Natural yogurt .057 .087 -.191 .368 .376 Sparkling water .042 -.115 -.621 .161 .004 Beer -.015 .278 -.032 .223 -.124 Plain porridge .248 -.135 -.031 .164 .656 Table salt .182 .609 -.004 .076 .254 Vinegar .357 .715 -.107 -.092 -.046 Parmesan cheese .520 .266 .367 .217 .289 Coffee granules .119 .724 .140 .163 .212 Lavender oil .098 .099 .539 .117 .265 Raw parsley .094 -.137 .660 -.083 .219 Mint herb .675 .318 .252 -.030 .233 Kidney beans .370 .012 -.080 .331 .380 Chilli powder .752 .120 -.165 -.187 -.005 Mackerel .771 -.120 .245 .236 .042 Smoked salmon .599 .004 .238 .467 -.094

Soda water .312 -.129 -.672 .035 .114 Minty chewing gum .405 .406 .378 -.263 -.323 Hard meringue .248 -.033 -.291 .747 .075 Sea water .629 .365 -.086 .016 -.179 Sugar .406 .381 .193 .277 -.401

Appendix 10

Factor loadings Component Matrix - Agreeability Taste 1 2 3 4 5 Fudge -.229 .462 -.053 -.062 .353 Raw garlic .755 .146 -.034 -.091 -.318 Black pepper .665 .038 .201 -.051 .114 Cooking oil .331 .314 .491 .084 .089 Tonic water -.003 .039 .496 -.105 .061 Soy sauce .629 -.033 -.092 .242 -.171 Raw thyme .775 .171 .016 -.052 .224 Raw onion .799 .120 .119 .106 .235 Smokey bacon .344 .375 .057 -.009 .151 Plain pasta .106 .214 .447 -.430 -.095 Raw ginger .782 -.043 -.237 .264 .204 Gouda cheese .682 .472 -.173 .131 -.162 Rose water .103 -.326 .303 .407 .255 Raw fennel .263 -.567 -.176 .174 .458 Whiskey .125 -.012 .130 -.330 .649 Mints .040 .408 -.001 -.019 .032 Red meat cooked rare .074 -.030 .050 .280 .413 Cream -.070 .704 .347 -.006 -.061 Pure lemon juice .649 -.203 .124 -.111 -.163 Maple syrup -.391 .232 -.326 .286 .230 Sea weed .385 -.031 -.066 .070 -.536 Dark Chocolate .383 .563 .119 -.251 -.159 Walnuts .178 -.173 .772 .313 .070 Liver -.192 -.075 .292 .106 .359 Strong goats cheese .200 -.017 -.510 -.178 .394 Cumin .598 .043 .137 .349 -.137 Smoked teas .188 .031 .284 .829 -.020 Water .070 -.024 -.149 .053 -.093 Vanilla .688 .039 -.020 -.306 -.014 Rosemary .793 .009 -.142 -.213 .057 Non flavoured antacids .190 .206 .164 .287 .322 Vodka .148 .037 .234 -.373 .708 Unsalted margarine -.374 .135 .443 .461 .094 Raw jalapeno pepper .267 .159 .464 .121 -.357 Natural yogurt .118 .348 .005 -.335 -.054 Sparkling water .045 .267 .763 .077 -.022 Beer .177 .000 .226 -.309 .090 Plain porridge .168 -.273 .039 -.782 .044 Table salt .556 .032 .058 .089 .208 Vinegar .570 .009 .064 .079 -.111 Parmesan cheese .647 .478 .014 .290 -.039 Coffee granules .278 .613 .098 -.010 .078 Lavender oil .272 -.087 -.357 .646 -.084 Raw parsley .667 -.205 -.072 .453 .240 Mint herb .733 -.149 -.129 -.182 -.023 Kidney beans -.056 .059 -.035 -.257 .013 Chili powder .436 .358 .409 -.046 -.256 Mackerel .375 -.256 .061 .263 .305 Smoked salmon .076 .039 -.055 .296 .727 Soda water -.233 -.179 .722 -.114 .369 Minty chewing gum .054 .423 .164 .118 -.437 Hard meringue .085 .494 -.262 .020 .341 58

Sea water .324 -.568 -.124 .043 .124 Sugar -.096 .854 -.045 .115 -.077