Nutritional supplements are often characterised by unpleasant tastes or aftertastes, primarily due to the presence of vitamins, minerals, and amino acids as active compounds. These taste defects can be masked by sweeteners or specific flavourings. However, the development of such strategies requires a thorough understanding of the sensory characteristics of nutritional supplements. In the present study, the sensory properties of four effervescent nutritional supplements, differing in composition, were evaluated using Quantitative Descriptive Analysis (QDA) across three modalities: orthonasal and retronasal odour perception, as well as aftertaste and aroma persistence. Bitterness, astringency, and metallic sensations were found to be responsible for the negative sensory attributes of the products in solution. The addition of flavouring agents was found to have either a positive or negative effect on the taste characteristics of the supplements. Indeed, certain fruity notes enhanced sweet and sour sensations and were found to mask negative sensory perceptions, although this effect varied depending both on the nature of the nutritional supplement and on the QDA modalities, mainly due to the oral process progressing. A better understanding of these perceptual interactions could provide a solution for masking strategies, potentially reducing the use of additives that can be expensive and detrimental to health.

Bitter is one of the five basic taste qualities, along with salty, sour, sweet and umami, used by mammals to access the quality of their food and orient their eating behaviour. Bitter taste detection prevents the ingestion of food potentially contaminated by bitter-tasting toxins. Bitter taste perception is mediated by a family of G protein-coupled receptors (GPCRs) called TAS2Rs. Humans possess 25 TAS2Rs (human type II taste receptors), enabling the detection of thousands of chemically diverse bitter compounds. The identification of agonists/antagonists and molecular mechanisms that govern receptor-ligand interaction has been primarily achieved through functional expression of TAS2Rs in heterologous cells. However, TAS2R receptors, like many other GPCRs, suffer from marginal cell surface expression. In this study, we compared the functionality of 9 engineered chimeric receptors, focusing our experiments on TAS2R14, a broadly tuned receptor that recognizes over 151 identified compounds. Among the different tested signal peptides, rat somatostatin receptor subtype 3 results in higher potency of aristolochic acid-induced calcium signalling than other tested export tags, such as bovine rhodopsin, murine Igκ-chain or human mGluR5. The addition of a MAX sequence enhances both TAS2R14 potency and efficacy. We also confirm that the FLAG epitope, when located at the C-terminal, interferes less with the TAS2R14 functionality, enabling reliable evaluation of this receptor at the cell surface using immunohistochemistry. Finally, these observations are also confirmed for TAS2R14 and TAS1R2/TAS1R3 (the sweet taste receptor) stimulated by 12 bitter compounds and by sucralose and neotame, respectively.

La perception des arômes et des saveurs joue un rôle important dans l’acceptabilité de l’aliment par le consommateur. Certaines perceptions conduisent à un rejet, tandis que d’autres plus appréciées incitent, par le plaisir, l’être humain à s’alimenter. Ces composés sapides et olfactifs, une fois libérés de l’aliment et rendus disponibles, interagissent avec des récepteurs, ce qui induit des processus complexes à différents niveaux pour conduire à la perception qui correspond à une réponse cérébrale. Les molécules odorantes, volatiles, atteignent l’épithélium olfactif situé dans la cavité nasale, soit par le nez (orthonasale), soit par la bouche (rétronasale). Les composés aromatiques atteignent les cils olfactifs après avoir traversé le mucus olfactif hydrophile par des mécanismes impliquant des transporteurs protéiques. Une fois cette étape franchie, les composés d’arôme interagissent alors avec les récepteurs olfactifs portés par les cils olfactifs en fonction de leurs propriétés physicochimiques et de la spécificité des récepteurs. Des mécanismes de transduction complexes du signal chimique olfactif permettent sa transformation en signal nerveux, qui se propage jusqu’au niveau central où le signal est traité et intégré. Les composés sapides, pour la plupart non volatils, dissous dans la salive sont détectés par des récepteurs gustatifs situés dans la cavité bucco-pharyngée, au niveau des papilles gustatives. Les différents stimuli sapides: acide, amer, sucré, salé, umami, stimulent spécifiquement des récepteurs de structure particulière. Des réactions en cascade, appelées globalement transduction, conduisent alors à la génération d’un influx nerveux qui est propagé jusqu’au système nerveux central par des neurones. Bien qu’au niveau périphérique, les systèmes de réception des stimuli soient bien différentiés entre arôme et saveur, des liens étroits existent entre ces deux modalités de perception au niveau central.

Artificial sweeteners (AS) are well known to activate two categories of receptors; sweet taste receptor with high affinity and bitter taste receptors with low affinity. Interestingly, recent data from our and other groups suggested that these two receptors families are expressed throughout the arterial tree. Therefore, it could be interesting to explore if AS may have an impact on vascular function, and to decipher the role of these taste receptors. The aims of this ongoing work is to investigate whether AS, like sucralose and acesulfame potassium (AceK) (1) exhibit vasomotor effect and (2) in that case determine the underlying mechanisms. Biomolecular and functional investigations have been performed on isolated rodent aortas, human dermal micro-arteries and omental arteries. Ex vivo vasomotor function was assessed using isometric tension measurements in organ bath systems. We first confirmed that both endothelial and smooth muscle cells from rodent and human arteries express the transcripts encoding for TAS1R2 and TAS1R3; the heterodimer receptor known to be responsible for the sweet taste. Our ex vivo data showed that only high concentrations (about 10 mM) of AceK and sucralose induce vasomotor responses. While AceK exhibited a vasoconstrictive effect, sucralose induced vasorelaxation. Both responses were found to be independent of the endothelium. Pharmacological inhibition (gurmarin and lactisol) and the use of a TAS1R3 KO mice model demonstrated that AS vasomotor effects do not rely on the sweet taste receptors. In contrast, inhibition of TAS2Rs abolished all responses suggesting that bitter taste receptors are more likely responsible for the AS-induced vascular effects. Additionally, our last observations show that the vasoconstrictive effect of AceK is mediated by RhoA/ROCK pathway. These evidences support the idea that AS can alter vasomotor signaling in the smooth muscle cells. These acute effects are probably mediated by the bitter taste receptor family. Their activation at the vascular level as well as the underlying pathways remains poorly understood, and the physiopathological consequences need to be further investigated.

Vitamins are known to generate bitterness, which may contribute to an off-taste or aftertaste for some nutritional supplements. This negative sensation can lead to a reduction in their consumption. Little is known about the bitter taste threshold and taste sensing system for the bitter taste detection of vitamins. To better understand the mechanisms involved in bitterness perception, we combined taste receptor functional assays and sensory analysis. In humans, bitter taste detection is mediated by 25 G-protein-coupled receptors belonging to the TAS2R family. First, we studied the bitterness of thirteen vitamins using a cellular-based functional taste receptor assay. We found four vitamins that can stimulate one or more TAS2Rs. For each positive molecule–receptor combination, we tested seven increasing concentrations to determine the half-maximal effective concentration (EC50) and the cellular bitter taste threshold. Second, we measured the bitter taste detection threshold for four vitamins that exhibit a strong bitter taste using a combination of ascending series and sensory difference tests. A combination of sensory and biological data can provide useful results that explain the perception of vitamin bitterness and its real contribution to the off-taste of nutritional supplements.

Vitamins play an important role in maintaining normal physiologic and metabolic functions. Vitamins are known to generate bitterness, which may contribute to the off-taste of nutritional supplements. This negative sensation may decrease product acceptability and patient compliance. Few studies have examined taste thresholds and sensory sensing mechanisms at the origin of vitamin taste detection. To better understand vitamin bitterness perception, we combined human sensory analysis and taste receptor functional assays. We measured the aqueous taste detection threshold of four B vitamins using sensory difference tests. Challenging the 25 human bitter taste 2 receptors (TAS2Rs), we found that three vitamins stimulated one or more receptors. For each positive molecule-TAS2R combination, we measured the half-maximum effective concentrations (EC 50 ). Thus, we found that the combination of sensory and biological data can provide useful explanations for the bitter detection of vitamins.

Orally Disintegrating Tablets (ODTs) are used to restore the nutritional status of people suffering from swallowing pathologies such as dysphagia. ODTs are consumed without water intake and are easily swallowed. The main active compounds of ODTs are vitamins and minerals. These nutrients can have a bad taste or aftertaste, which can be masked by sweetening or flavoring. To ensure the effectiveness of masking strategies and to prescribe a product to patients with acceptable sensory qualities, it is essential to perform a precise and complete sensory characterization of these ODTs. Temporal dominance of sensations (TDS) and temporal check-all-that-apply (TCATA) methods were chosen to characterize the temporal sensory perceptions during the consumption of four ODTs varying in galenic forms and flavoring because of their particularly acute temporality in flavor perception. The ODTs presented common and individual sensory properties, mainly related to their galenic form and to the nature of the active ingredients. The use of a nose-clip to stop retro-nasal airflow showed that flavoring had a minimal impact on the sensory taste qualities of the ODTs. A comparison between the TDS and TCATA results indicates that these tests are capable of providing complementary information on the dynamic sensory qualities of the products studied. Although results were generally similar for both methods, TDS showed a greater number of differences in sensory taste attribute, whereas TCATA was more discriminating. These methods allowed for a better understanding of the evolution of sensory perceptions of these ODTs during their consumption, which could help to optimize masking strategies and develop new products with acceptable sensory properties.

Animals need to detect in the food essential amino acids that they cannot synthesize. We found that the odorant binding protein OBP19b, which is highly expressed in Drosophila melanogaster taste sensilla, is necessary for the detection of several amino acids including the essential l -phenylalanine. The recombinant OBP19b protein was produced and characterized for its binding properties: it stereoselectively binds to several amino acids. Using a feeding-choice assay, we found that OBP19b is necessary for detecting l -phenylalanine and l -glutamine, but not l -alanine or D -phenylalanine. We mapped the cells expressing OBP19b and compared the electrophysiological responses of a single taste sensillum to several amino acids: OBP19b mutant flies showed a reduced response compared to control flies when tested to preferred amino acids, but not to the other ones. OBP19b is well conserved in phylogenetically distant species suggesting that this protein is necessary for detection of specific amino acids in insects.

Nutritional supplements are prescribed when one's nutritional status is not conducive to good health. These foodstuffs constitute concentrated sources of nutrients such as vitamins, minerals, amino acids, and fatty acids. For nutritional supplements to be effective, patients must consume the amount that has been prescribed for the recommended period of time. Therefore, special attention must be given to the sensory attributes of these products. Indeed, the presence of active compounds can cause an off-taste or aftertaste. These negative sensations can lead to a reduction in the consumption of nutritional supplements and reduce the effectiveness of the treatment. In this manuscript, we provide an overview of the sensory characteristics and the sensing receptor mechanism of the main compounds present in oral nutritional supplements, such as amino acids, minerals, fatty acids, and vitamins. Part of this article is devoted to the development of new masking strategies and the corresponding potential influence at the industrial level.