Bitter Sensations Research Articles

Taste and oral somatosensation: Role of PTC bitter sensitivity, gender, and age

Sensitivity to the bitterness of phenylthiocarbamide (PTC) is considered to be linked to general taste perception, which is higher in women, and exhibits a slight decrease with age. Additionally, PTC sensitivity may contribute to somatosensory perception of spiciness and astringency. However, controversial data have been reported. This study investigates the relation between PTC perception, age, and gender on taste and somatosensory sensitivity using the Seven-iTT. A total of 200 healthy participants were classified based on their PTC perception, and subjects underwent an extended version of Seven-iTT to identify and rate the intensity of twelve stimuli. Results indicated that individuals classified as Tasters (T) exhibited higher taste scores compared to Non-Tasters (NT) for PTC, with age serving as a significant factor (p ≤ 0.009). Women outperformed men only among NT (p = 0.019). Older T demonstrated higher taste sensitivity than NT, suggesting that PTC status might act as a protective factor of gustatory function in aging. While PTC taster status significantly affected the intensity of sweet, salty, and bitter sensations (p ≤ 0.032), it had minimal impact on the intensity of somatosensory sensations (capsaicin and tannins). The combined use of Seven-iTT and the investigation of PTC status show promise for applications in research and clinical practice, offering a comprehensive approach to understanding taste perception and its implications for diet, nutrition, and aging.

Diagnostic Infrared Thermography of the Tongue and Taste Perception in Patients with Oral Lichen Planus: Case-Control Study.

Oral lichen planus (OLP) is a chronic inflammatory disease of autoimmune origin that affects the skin and mucous membranes. The aim of this study was to assess the effectiveness of infrared thermography (IRT) as a diagnostic tool in patients with oral lichen planus (OLP), as well as disturbances in taste perception, in cases with and without tongue involvement. A case-control study was carried out in a sample of 87 patients divided into three groups: healthy individuals (controls; n = 43), OLP patients without involvement of the tongue (n = 24), and OLP patients with involvement of the tongue (n = 20). The patient symptoms and the clinical characteristics of the lesions were assessed. Four thermal images of the tongue were obtained using IRT: dorsum, right and left lateral surface, and tip of the tongue. General taste perception capacity and subjective sweet, acid, salty, and bitter sensation were evaluated in all three groups. There were no statistically significant differences in the IRT values among the three groups (p ≥ 0.05). In the OLP patients with involvement of the tongue, significantly higher values were observed in the mixed forms of the disease (p = 0.032). The OLP patients with and without involvement of the tongue showed no significant alterations in taste sensation (p = 0.69). IRT may serve as a complementary tool for assessing the activity of OLP with involvement of the tongue. However, more research is needed in this field.

Gender Differences in Taste Sensations Based on Frequency Analysis of Surface Electromyography

Males and females respond differently at the muscular level to various tastes and show varied responses when eating different foods. In this study, we used surface electromyography (sEMG) as a novel approach to examine gender differences in taste sensations. We collected sEMG data from 30 participants (15 males, 15 females) over various sessions for six taste states: a no-stimulation physiological state, sweet, sour, salty, bitter, and umami. We applied a Fast Fourier Transformation to the sEMG-filtered data and used a two-sample t-test algorithm to analyze and evaluate the resulting frequency spectrum. Our results showed that the female participants had more sEMG channels with low frequencies and fewer channels with high frequencies than the male participants during all taste states except the bitter taste sensation, meaning that for most sensations, the female participants had better tactile and fewer gustatory responses than the male participants. The female participants responded better to gustatory and tactile perceptions during bitter tasting because they had more channels throughout the frequency distribution. Moreover, the facial muscles of the female participants twitched with low frequencies, while the facial muscles of the male participants twitched with high frequencies for all taste states except the bitter sensation, for which the female facial muscles twitched throughout the range of the frequency distribution. This gender-dependent variation in sEMG frequency distribution provides new evidence of differentiated taste sensations between males and females.

The Bitter Touch: Acquired Tactile-Gustatory Synesthesia

AbstractIntroductionGustatory sensation in response to tactile stimulation has been reported to occur in only 0.6% of synesthetes and has rarely been formally described.MethodsCase Study: A 29-year-old female with schizoaffective disorder – depressed subtype, two months prior to presentation, began noticing that when she touched objects, she would experience an abnormal taste in her mouth. When she would touch specific items with her fingertips, for instance wood, bedsheets, tables, cups, plates, silverware, metal, trash cans, and toothpaste would induce a bitter taste. Touching wood caused the most intense bitter taste. Touching glass did not precipitate a taste.ResultsMental Status Examination: Disheveled and guarded with minimal eye contact. Anxious and agitated. She believes people are stalking her and that cell phones, radios, and computers emit radiation which makes her head burn as if it is on fire. She perceived that inanimate objects, such as furniture, were staring at her. Other: CT scan of brain with and without contrast: normal.DiscussionThis could be due to neural overactivation between brain regions due to a neighborhood effect, with cross-firing of connecting fibers. The cortical taste area of the brain lies within the Brodmann area 43 of the parietal lobe which includes the pre- as well as post-central gyri extending into the parietal operculum. Brodmann areas 3, 1, and 2 in the postcentral gyrus is where the primary sensation for touch is mediated. The stimulation in adjacent and overlapping anatomical structures may be explained by ephaptic transmission with firing of one causing discharge of the second, yclept the adjacency principle.This co-localization hypothesis is further supported by the occurrence of pathological state of seizures which manifest both tactile and gustatory sensation. Such a hypothesis would be supported by Anderson’s 1886 observation discussing a peculiar sensation in the right arm and hand elicited concurrently with a bitter sensation in the mouth. Through an overflow phenomenon, touch may induce a diffuse serotonergic discharge to more remote regions of the brain that may mediate their functions through serotonin, such as taste. Possibly, other pathology may be invoked to explain this synesthesia. A deprived sensory system may be hyper-receptive to stray or overflow of sensations which are then interpreted within the sensorily deprived sensory system, as in Charles Bonnet syndrome. In the chemosensory sphere, sensory deprivation is associated with chemosensory hallucinations. If the patient manifests gustatory deficit, it may have predisposed her to sensitivity to such stray or overflowing sensory stimulus from touch manifesting as gustation. In those who present with synesthesia, investigation of pathology in the sensory system of the receiving concurrent sensation is warranted.FundingNo Funding

The effect of background music on sensory evaluation of craft beer

The present study sought to evaluate the influence of different musical genres on the temporal description of sensations and the global acceptability of IPA New England style craft beer. The dominant sensations were determined using the temporal dominance of sensations (TDS) method with 50 participants submitted to five sound conditions: absence of music and four musical genres (classic rock, sertanejo, pop and soft rock). The sensorial acceptability of craft beer was assessed using the 9-point hedonic scale, with 140 consumers, in the same consumption contexts. The TDS curves indicated significant diferences (p < 0.05) in sensory perception of the beverage in the different consumption environments. The bitterness sensation was present in all sound conditions. However, for each musical genre a different sensation was present, reported as fruity flavor for classic rock, refreshing for pop, lightness for soft rock and astringency for sertanejo. Craft beer showed greater acceptance when consumed to the sound of classic rock. Thus, some musical genres can be effectively used to influence the experience of tasting and consuming food and beverages, such as craft beer, making it possible to modify or intensify the dominant sensation and acceptability of the beverage. In addition, ambient music can be used by producers and traders as a tool to differentiate and expand the attractions for the target audience of this product.

Evolutionary insights into umami, sweet, and bitter taste receptors in amphibians.

Umami and sweet sensations provide animals with important dietary information for detecting and consuming nutrients, whereas bitter sensation helps animals avoid potentially toxic or harmful substances. Enormous progress has been made toward animal sweet/umami taste receptor (Tas1r) and bitter taste receptor (Tas2r). However, information about amphibians is mainly scarce. This study attempted to delineate the repertoire of Tas1r/Tas2r genes by searching for currently available genome sequences in 14 amphibian species. This study identified 16 Tas1r1, 9 Tas1r2, and 9 Tas1r3 genes to be intact and another 17 Tas1r genes to be pseudogenes or absent in the 14 amphibians. According to the functional prediction of Tas1r genes, two species have lost sweet sensation and seven species have lost both umami and sweet sensations. Anurans possessed a large number of intact Tas2rs, ranging from 39 to 178. In contrast, caecilians possessed a contractive bitter taste repertoire, ranging from 4 to 19. Phylogenetic and reconciling analysis revealed that the repertoire of amphibian Tas1rs and Tas2rs was shaped by massive gene duplications and losses. No correlation was found between feeding preferences and the evolution of Tas1rs in amphibians. However, the expansion of Tas2rs may help amphibians adapt to both aquatic and terrestrial habitats. Bitter detection may have played an important role in the evolutionary adaptation of vertebrates in the transition from water to land.

Genetic preferences for food

Genetic preferences for food

Exploring the multisensory perception of terpene alcohol and sesquiterpene rich hop extracts in lager style beer

Understanding the contribution of hop essential oil to the multisensory profile of beer is known to be challenging because of its chemical and sensory complexity. Limited research has been conducted investigating hop-derived volatiles' role in the modulation of taste and mouthfeel sensations. Supercritical CO₂ can be used to extract specific fractions from hop oil, thereby enabling the localisation of compounds responsible for different sensory impressions. Terpene alcohol and sesquiterpene fractions were extracted from a Magnum hop oil and further fractionated into seven sub-fractions and individual compounds. All extracts were evaluated in lager (4.5% v/v) by a trained panel (n = 10) using a newly developed attribute lexicon and following a sensory descriptive analysis approach. The sensory data was analysed using ANOVA, followed by Tukey’s test (HSD) and correlated with chemical profile data obtained by gas chromatography-mass spectrometry (GC–MS) by Principal Component Analysis. The study revealed evidence for hop extracts to impart multisensory characteristics to beer due to sensory interactions within and across modalities. The monoterpene alcohols-rich fractions and particularly geraniol, added fruity- and floral aromas and flavours, modified the sweetness and induced a smooth bitterness in the beer matrix. Flavouring the beer with sesquiterpene fractions resulted in a harsh bitterness sensation. Contrary to previous findings, the humulene epoxides fraction appeared to have limited effects on lingering bitterness and astringency, illustrating the need for temporal sensory assessments in future studies. This research shows that splitting hop oil into fractions and sub-fractions provides a source of natural, sustainable flavouring preparations with distinct sensory characteristics.

The effect of different tonsillectomy techniques on taste sensation in the early and late postoperative periods

Objectives: Impairment in taste sensation is a rare complication of tonsillectomy. We aimed to reveal the effects of different tonsillectomy techniques on taste sensation by assessing the impairment in taste sensation in the early and late postoperative periods. Methods: In this prospective clinical study, fifty-seven (22 females, 35 males, mean age, 25 ± 9.8 years) patients who underwent tonsillectomy were included. All patients were operated on under general anesthesia, and a chemical stimulation taste test was performed one week prior to the surgery, at first week and first month postoperatively. Four basic taste sensations were assessed in the test (sweet, sour, salty, and bitter), and impairments in taste sensation in the early and late postoperative periods for each tonsillectomy technique were evaluated. Results: In the early postoperative period, there was a statistically significant increase bitter taste sensations in patients who underwent tonsillectomy (p = 0.020). In the late postoperative period, sour and bitter taste sensations were significantly increased in the patients (p = 0.001, p = 0.002; respectively). In contrast to the early postoperative period, total taste sensation was significantly increased in the late postoperative period (p = 0.034). Conclusions: The bitter sensation in the early postoperative period and the bitter and sour sensations in late postoperative period were found to be significantly increased in this present study.With regard to these results, a thorough preoperative explanation should be done.

Deciphering molecular mechanics in the taste masking ability of Maltodextrin: Developing pediatric formulation of Oseltamivir for viral pandemia

Present research work was aimed at masking the bitter taste of anti- viral drug Oseltamivir phosphate (Ost) by complexing it with pea starch maltodextrin- Kleptose Linecaps® (Mld). The Ost groups involved in triggering the bitter sensation were identified by computationally assessing its interaction with human bitter taste receptor hTAS2R 38. A series of exhaustive molecular dynamics (MD) simulation was run using Schrodinger® suite to understand the type of interaction of Ost with Mld. Experimentally, complexes of Ost with Mld were realized by solution method. The complexes were characterized using differential scanning colorimetry (DSC), fourier transform-infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), hot stage microscopy (HSM), scanning electron microscopy (SEM), proton NMR (1H-NMR) and Carbon-13 nuclear magnetic resonance (13C-NMR). Ost-oral dispersible mini tablets (ODMT) were prepared by direct compression and optimised using mixture designs. Finally, bitter taste perception of Ost-ODMT was evaluated in healthy human volunteers of either sex. Computational assessment, involving interaction of Ost with bitter receptor, predicted the involvement of free amino group of Ost in triggering the bitter response whereas, MD simulation predicted the formation of stable complex between Ost and double helical confirmation of Mld. Different characterization techniques confirmed the findings of MD simulation. Results from the taste assessment in human volunteers revealed a significant reduction in bitter taste of prepared Ost-ODMT

Pharmacology of T2R Mediated Host-Microbe Interactions.

Bitter taste receptors (T2Rs) belong to the G protein-coupled receptor superfamily. Humans express 25 T2Rs that are known to detect several bitter compounds including bacterial quorum sensing molecules (QSM). Primarily found to be key receptors for bitter sensation T2Rs are known to play an important role in mediating innate immune responses in oral and extraoral tissues. Several studies have led to identification of Gram-negative and Gram-positive bacterial QSMs as agonists for T2Rs in airway epithelial cells and immune cells. However, the pharmacological characterization for many of the QSM-T2R interactions remains poorly defined. In this chapter, we discuss the extraoral roles including localization of T2Rs in extracellular vesicles, molecular pharmacology of QSM-T2R interactions, role of T2Rs in mediating innate immune responses, and some of the challenges in understanding T2R pharmacology.

Quantitation and Taste Contribution of Sensory Active Molecules in Oat (Avena sativa L.).

A total of 59 taste-active molecules were quantitated and then rated for their individual taste impact on the basis of dose-over-threshold factors in oat flour (Avena sativa L.). A sensitive high-performance liquid chromatography-tandem mass spectrometry method was developed to quantitate bitter-tasting steroidal and furostanol saponins as well as avenanthramides. Four monoglycerides, five free fatty acids and four saponins were confirmed for the first time to be major contributors to the bitter off-taste of oats, among them 1-linoleoyl-rac-glycerol, 1-stearoyl-rac-glycerol, 1-oleoyl-rac-glycerol, 1-palmitoyl-rac-glycerol, linoleic acid, linolenic acid, oleic acid, palmitic acid, and stearic acid as well as avenacosides A and B and the recently identified furostanosides 3-(O-α-l-rhamnopyranosyl(1→2)-[β-d-glucopyranosyl(1→3)-β-d-glucopyranosyl(1→4)]-β-d-glucopyranosid)-26-O-β-d-glucopyranosyl-(25R)-furost-5-ene-3β,22,26-triol and 3-(O-α-l-rhamnopyranosyl(1→2)-[β-d-glucopyranosyl(1→4)]-β-d-glucopyranosid)-26-O-β-d-glucopyranosyl-(25R)-furost-5-ene-3β,22,26-triol. By means of a stable isotope dilution assay, quantitated avenanthramides 2c, 2p, 2f, 1p, 1c, 1f, and 3f were found in concentrations below their thresholds and, therefore, did not contribute to the bitter sensation of the tested oat flour.

The determinants of chemoreception as evidenced by gradient boosting machines in broad molecular fingerprint spaces

The ability to identify and reject bitter molecules may determine evolutionary fitness. These molecules might be in potentially toxic or contaminated food. Surprisingly, the ability to identify but tolerate or even enjoy bitter foods and medicines may be beneficial. For example, the tolerance of bitterness as a spice or as a medicine may lead to better nutritional, immunological and health outcomes. More recently the ability of intensely bitter compounds to induce innate immune responses to counter infection has inspired the screening of new drugs and the repurposing of safe, known drugs to new uses. These avenues of study may also help to address long-standing questions regarding unexpected side-effects and placebo/nocebo effects. Therefore, to distinguish all these effects ranging from desire to aversion, there is a need to quantitatively determine the concentration thresholds and to position these bitter substances on a unified taste threshold spectrum. Such an understanding may help elucidate the concentration-based molecular drivers for the chemoreceptive response to bitter substances. This article reports the development of a gradient boosting machine (GBM) that enables a direct interrogation of molecular structure with no intermediary chemical properties. Using molecularly engineered simulations, it is shown that potassium acesulfame has a hidden bitterness motif that is centered on the chemoreceptive spectrum uniting bitterness and sweetness molecular motifs. The resultant shifted perception from a touchstone bitterness sensation to a bitter after-taste is attributable to this cached molecular motif.

Smart breeding for salad rocket: a strategy for improving taste, flavor and nutrition

Eruca sativa (salad rocket) is a leafy salad that contains numerous health beneficial compounds. These include glucosinolates and their hydrolysis products isothiocyanates, which have anti-carcinogenic properties. These compounds also influence taste and flavour of leaves, giving hot, pungent and bitter sensations. Breeding efforts for minor crops such as rocket have to-date been restricted to morphological traits. We outline a strategy for collaboration between academia and industry to improve advanced traits such as phytochemical composition, taste, flavour and nutrition. This can be achieved by combining the development of genetic resources, utilisation of next generation sequencing technologies and bioinformatics with sensory and phytochemical analyses. The implementation of such technologies into minor crop breeding programs will speed up the development of new cultivars and greatly improve understanding of an underutilised Brassicaceae crop.

Mechanistic role of plant-based bitter principles and bitterness prediction for natural product studies I: Database and methods

Abstract This chapter discusses the rationale behind the bitter sensation elicited by chemical compounds, focusing on natural products. Emphasis has been placed on a brief presentation of BitterDB (the database of bitter compounds), along with available methods for the prediction of bitterness in compounds. The fundamental basis for explaining bitterness has been provided, based on the structural features of human bitter taste receptors and have been used to shed light on the mechanistic role of a few out of the 25 known human taste receptors to provide the foundation for understanding how bitter compounds interact with their receptors. Some case studies of ligand-based prediction models based on 2D fingerprints and 3D pharmacophores, along with machine learning methods have been provided. The chapter closes with an attempt to establish the relationship between bitterness and toxicity.

Physicochemical changes and bitterness of whey protein hydrolysates after transglutaminase cross-linking

Whey protein hydrolysates are widely used in hypoallergenic formulas. The extensive hydrolysis required to reduce the protein antigenic potential frequently generates bitter-tasting peptides. This study investigates the effect of transglutaminase (TG) catalyzed cross-linking on physicochemical characteristics and bitter taste of whey protein hydrolysates. The chromatographic analysis showed a slight increase in the relative concentration of peptides (p < 0.05) with molecular mass of 1.4–3.5 kDa (SEC-HPLC) and changes in peak intensity and peptide hydrophilicity after TG-treatment (RP-HPLC). The MALDI-MS peptide fingerprinting presented changes in relative intensities and suppression of signals after TG-treatment, suggesting that cross-linking occurred, mainly in the m/z 1600–3000 range peptides. Changes in the spatial conformation of peptides after TG-treatment were evidenced by the intrinsic fluorescence of the samples. Despite the changes in the physicochemical characteristics of peptides, no differences (p > 0.05) in the intensity (6–7, on a scale up to 9) and duration (38 s) of the bitterness sensation were observed. Possibly, the presence of free glutamine and the significant amount of short peptides with no glutamine or lysine residue may have decreased the opportunities for cross-linking formation; therefore, the presence of bitter-tasting peptides was unchanged as a consequence of TG-treatment.

Hen protein-derived peptides as the blockers of human bitter taste receptors T2R4, T2R7 and T2R14

Bitter sensation is mediated by various bitter taste receptors (T2Rs), thus T2R antagonists are actively explored. Our objective was to look for novel T2R blockers in hen protein hydrolysate (HPH). We screened the least bitter HPH fractions using electronic tongue, and analyzed their peptide sequences and calcium mobilization in HEK293T cells expressing T2Rs. The results showed that the HPH fractions with higher bitterness intensity had higher hydrophobicity, more hydrophobic amino acids, and more positively charged peptides, but fewer known umami peptides. The peptide fractions from the least bitter HPH fraction significantly inhibited quinine bitterness (P < 0.05), and also significantly inhibited quinine- or diphenhydramine-dependent calcium mobilization of HEK293T cells expressing human T2R4, T2R7, or T2R14 (P < 0.05). Among them, the first eluted (least bitter) peptide fraction showed the strongest bitter-inhibitory effect. In conclusion, HPH peptides are the blockers of T2R4, T2R7, and T2R14.

The Origin of Unpleasant Aftertastes in Synthetic Sweeteners: A Hypothesis.

Most sweeteners are plagued with unwanted unpleasant aftertastes. Here we examined the possibility that one of the main reasons for this is the similarity of sweet and umami receptors. We performed docking calculations on models of sweet and umami receptors using as template the recently determined solid state structure of the first taste receptor, the medaka fish T1R2-T1R3 receptor. Our results show convincingly that sweeteners can be recognized also by the T1R1-T1R3 umami receptor, owing to the similarity of its architecture to that of the sweet receptor. We hypothesize that the T1R1-T1R3 receptor plays a key role in modulating the quality of sweet tastants, hinting at a simple explanation of their aftertaste. The prevailing ideas on taste coding favor strict labeling of taste cells, which would exclude that umami receptors can recognize other taste sensations. If some cross-talk based on the combinatorial model of taste is accepted, some sweet ligands can exert a bitter sensation. However, even if cross-talk is not admitted, direct stimulation of the umami receptor is bound to cause an aftertaste incompatible with good sweet quality.

Management of Pseudomembranous Candidiasis on The Tongue of A Smoker Patient

Introduction: Candidiasis is an oral opportunistic infection caused by Candida albicans (C. albicans). This fungus may cause a pathogenic condition, and is the most common fungal infection in the human oral cavity. Candida albicans causes infection more frequently compared to other types of fungus, e.g. C. tropicalis, C. krusei, C. parapsilosis, C. guilliermondi. Predisposing factors e.g. the use of dentures, xerostomia, and smoking habits are known to cause the occurrence of oral candidiasis. Objective: To determine the management of Acute Pseudomembranous Candidiasis. Case: A 52-year-old male patient visited the Oral Medicine Clinic of Dental Hospital, Dentistry Faculty, Jember University complaining about his tongue suffering from thickening, white, and feeling uncomfortable when eating. The patient claimed hurt, and tasted bitter sensation while eating. Conclusion: The patient was completely diagnosed to suffer from pseudomembranous candidiasis on his tongue. Management: The therapy provided for the patient was Nystatin oral suspension functioning as a topical antifungal medicine, Becomzet (Vitamin B complex, A, C, E, and Zinc), tongue cleaner number 1 as a tongue cleanser appliance. Keywords: Nystatin oral suspension, Pseudomembranous candidiasis, Tongue

Sensory profiling and consumer acceptability of new dark cocoa bars containing Tuscan autochthonous food products.

A new set of cocoa bars named Toscolata® were developed containing top‐quality extra virgin olive oil, dried apples cultivars, and chestnut flour. The present work has been conducted to define the sensory profile of these products through tasting by trained experts and consumers to study the acceptability, preference, and quality perception. The four sensorial profiles of the bars differed in the level of persistence, bitterness, aromaticity, acidity, astringency, and tastiness. In particular, the sour attribute could be traced to the presence of dried apple. Bars containing apple and chestnut flour obtained higher acceptance ratings, compared to those with extra virgin olive oil. The bar with chestnut flour was preferred by consumers who considered it to be sweeter due to the presence of natural sugars, which lowered the bitter sensation of cocoa. These results showed that the selection of the preferred bar by consumers was mainly based on the level of bitterness and, in particular, elderly consumers expressed a strong preference for the sweetest product. As far as we know, this is the first study comparing the results of a panel of expert tasters with that of consumers in the tasting of dark chocolate.