Basic Tastants Research Articles

The role of GABA in modulation of taste signaling within the taste bud.

Taste buds contain 2 types of GABA-producing cells: sour-responsive Type III cells and glial-like Type I cells. The physiological role of GABA, released by Type III cells is not fully understood. Here, we investigated the role of GABA released from Type III cells using transgenic mice lacking the expression of GAD67 in taste bud cells (Gad67-cKO mice). Immunohistochemical experiments confirmed the absence of GAD67 in Type III cells of Gad67-cKO mice. Furthermore, no difference was observed in the expression and localization of cell type markers, ectonucleoside triphosphate diphosphohydrolase 2 (ENTPD2), gustducin, and carbonic anhydrase 4 (CA4) in taste buds between wild-type (WT) and Gad67-cKO mice. Short-term lick tests demonstrated that both WT and Gad67-cKO mice exhibited normal licking behaviors to each of the five basic tastants. Gustatory nerve recordings from the chorda tympani nerve demonstrated that both WT and Gad67-cKO mice similarly responded to five basic tastants when they were applied individually. However, gustatory nerve responses to sweet-sour mixtures were significantly smaller than the sum of responses to each tastant in WT mice but not in Gad67-cKO mice. In summary, elimination of GABA signalling by sour-responsive Type III taste cells eliminates the inhibitory cell-cell interactions seen with application of sour-sweet mixtures.

Can humans smell tastants?

Although studies have shown that olfaction may contribute to the perception of tastant, literature is scarce or circumstantial, especially in humans. This study aims to (i) explore whether humans can perceive solutions of basic prototypical tastants through orthonasal and retronasal olfaction and (ii) to examine what volatile odor compounds (VOCs) underlie this ability. Solutions of 5 basic tastants (sucrose, sodium chloride, citric acid, monosodium glutamate [MSG], quinine) dissolved in water, and 2 fatty acids (oleic and linoleic acid) dissolved in mineral oil were prepared. Triangle discrimination tests were performed (n = 41 in duplicate) to assess whether the tastant solutions can be distinguished from blanks (solvents) through ortho- and retronasal olfaction. Participants were able to distinguish all tastant solutions from blank through orthonasal olfaction. Only sucrose, sodium chloride, oleic acid, and linoleic acid were distinguished from blank by retronasal olfaction. Ethyl dichloroacetate, methylene chloride, and/or acetone were identified in the headspace of sucrose, MSG, and quinine solutions but not in the headspace of water, sodium chloride, and citric acid solutions. Fat oxidation compounds such as alcohols and aldehydes were detected in the headspace of the oleic and linoleic acid solutions but not the mineral oil. We conclude that prototypical tastant solutions can be discriminated from water and fatty acid solutions from mineral oil through orthonasal olfaction. Differences in the volatile headspace composition between blanks and tastant solutions may have facilitated the olfactory discrimination. These findings can have methodological implications for future studies assessing gustatory perception using these prototypical taste compounds.

Quantitative Proton NMR Spectroscopy for Basic Taste Recombinant Reconstitution Using the Taste Recombinant Database.

The quantitative determination of putative taste active metabolites, the ranking of these compounds in their sensory impact based on dose-overthreshold (DoT) factors, followed by confirmation of their relevance by reconstitution and omission experiments enables the decoding of the non-volatile sensometabolome of certain foods. The identification and quantitation of target taste compounds by liquid chromatography-tandem mass spectrometry (LC-MS/MS), high-performance liquid chromatography-ultraviolet/visible (HPLC-UV/Vis) spectroscopy, or high-performance ion chromatography (HPIC) is often laborious and time-consuming. In this work, we present a novel quantitative 1H NMR approach for reconstituting basic taste recombinants of different foods, including apple juice, balsamic vinegar, golden chanterelles, process flavor, and shrimp. Compound identification using the taste recombinant database, followed by absolute quantitation via quantitative 1H NMR (qHNMR), enables a fast and direct reconstitution of basic taste recombinants. The taste profile analysis of basic taste recombinants was generated via qHNMR in less than 15 min and compared with literature data acquired by LC-MS/MS and/or HPLC-UV/Vis and revealed identical results for all taste qualities. A determination of limit of detection (LoD) values for S/N = 50 of various proton signals with different integrals and multiplicities demonstrated that taste recognition thresholds of all basic tastants are far above those of LoD concentrations under the chosen conditions. Therefore, our experimental setup is able to detect basic taste-active compounds well below their taste recognition thresholds.

Comparative Evaluation of Altered Taste Perception among Oral Submucous Fibrosis Patients

Background:Taste perception is an important factor in sustaining human life. Impairment of taste is one of the important features of oral submucous fibrosis (OSMF), and it has not received much attention, owing to limited research work in the field. Therefore, the present study was conducted to determine taste alteration in OSMF patients.Materials and Methods:A total of 200 participants, both males and females with the age range of 20 years to 55 years, were included in the study. Four basic tastants (i.e., sweet, salt, sour, and bitter) were prepared as follows: sucrose for sweet (0.1–1.0 mol/l), sodium chloride for salty (0.01–1.0 mol/l), citric acid for sour (0.320–0.032 mol/l), and quinine sulfate for bitter (0.01–1.0 mol/l) and full mouth rinse test was performed for a complete taste response examination, after which punch biopsy was taken from buccal mucosa to determine histopathological staging. The data obtained were tabulated and analyzed by the Pearson Chi-square test; P < 0.05 was considered statistically significant.Results:The overall results suggested that there was a significant alteration of taste. The sweet taste was altered followed by salty and bitter was least affected.Conclusion:The study points out at the significance of alteration in taste perception is OSMF patients related to sweet, salt, sour, and bitter taste by using physiological stimuli tastants.

The flavor chemistry of pork broth: a review

Pork is widely consumed in the world. The unique and attractive flavor is one of the major drivers of consumer liking for pork. Even though the flavor of pork products varies heavily depending on the processing and cooking method, pork broth is very popular in East Asian countries and could serve as a perfect model for studying the flavor chemistry of pork. While quite a number of studies have been carried out on this topic, only a few meet the basic criteria of modern flavor chemistry approaches. By reviewing these publications, 12 volatile compounds, including 4 sulfur containing compounds, 4 aldehydes, 1 alcohol, 1 ester, 1 lactone, and 1 carboxylic acid, were selected as the major aroma active components in pork broth. While the taste of pork broth mainly comes from the basic tastants such as amino acids, organic acids, inorganic minerals, and nucleotides, the role of taste modifiers in pork broth has yet to be investigated. More research is needed to further clarify the flavor chemistry of pork broth.

Normative data on the subjective gustatory function of Chinese adults.

Purpose: the study aims to assess the gustatory function of healthy Chinese adults with the whole-mouth test based on five basic tastants, including umami taste. Methods: the study recruited 464 participants reporting a normal sense of smell/taste (227 females and 237 males with an age range of 19-65 years). A drop (approximately 0.1 mL) of liquid tastant was applied on the anterior third of the extended tongue of each subject. The taste solutions involved 5 tastants (sour, sweet, salty, umami, and bitter) and 7 concentrations. Taste perception scores and recognition scores of the five basic tastants were obtained with this whole-mouth taste method. Results: total taste score of recognition showed a significant negative correlation with age. The elder group (51-65 years) had the lowest scores. The 10th percentile of total taste score of recognition in the group of 36 to 50 years was used to distinguish normogeusic subjects from hypogeusic subjects. The perception scores and recognition scores of females were higher than those of males. The perception and recognition scores of salty, umami, and bitter for females were high than those for males. Total taste score of recognition for non-smokers was significantly higher than that of smokers. The whole-mouth method showed a high test-retest reliability with an intra-class correlation coefficient (ICC) from 0.774 to 0.833. Conclusion: this whole-mouth method is simple and time-saving and can be easily adjusted to obtain reliable data. The gustatory function was significantly negatively correlated with age. Females were more sensitive to the sour, salty, umami and bitter tastes than males. The gustatory function of non-smokers was more sensitive.

Homogeneity of thermal tasters and implications for mechanisms and classification

Thermal tasting, an important type of individual variation in orosensation, is a phenomenon by which some individuals perceive thermally-induced taste sensations simply by having the tip of their tongue warmed or cooled. These individuals, known as thermal tasters, report a variety of thermally-elicited tastes (typically sweet, sour, salty, bitter, metallic) and the tastes reported can vary with the temperature regime used (warming or cooling) and location on the tongue tested. Importantly, when compared to thermal non-tasters, thermal tasters are more responsive to aqueous solutions of basic tastants and to beverages. The mechanism(s) underlying thermal tasting are not well understood and it is unknown if the increased orosensory responsiveness of thermal tasters is universal or if it is driven by a subgroup of thermal tasters. Thermal taste data from 12 previous studies was combined to obtain a large sample of thermal tasters (n = 254) who were divided into subgroups based on the type of thermally-elicited taste reported and the temperature regime/location at which it was experienced. Sweet thermal tasters (n = 77) were 9 times more likely than non-sweet thermal tasters (n = 177) to experience thermally-elicited sensations during lingual warming (p < 0.0001). Similarly, sour thermal tasters (n = 89) were 8 times more likely than non-sour thermal tasters (n = 165) to report thermally induced tastes during cooling (p<0.0001). However, no differences in orosensory responsiveness based on these or other subgroups were identified, suggesting that the heightened orosensory responsiveness of thermal tasters may be centrally-mediated. We discuss how these findings inform our understanding of the mechanism(s) underlying thermal taste and the identification of thermal taste subgroups, along with practical implications of methodological differences in determining thermal taste status.

Chemosensory Sensitivity after Coffee Consumption Is Not Static: Short-Term Effects on Gustatory and Olfactory Sensitivity.

Chemosensory sensitivity has great variation between individuals. This variation complicates the chemosensory diagnostics, as well as the creation of a meal with universally high hedonic value. To ensure accurate characterization of chemosensory function, a common rule of thumb is to avoid food/beverages one hour before chemosensory testing. However, the scientific foundation of this time of fast remains unclear. Furthermore, the role of coffee on immediate chemosensitivity is not known and may have implications for optimization of gastronomy and hedonia. The aim of this study is to investigate the modularity effects of coffee consumption on immediate gustatory and olfactory sensitivity. We included 155 participants. By applying tests for olfactory and gustatory sensitivity before and after coffee intake, we found no changes in olfactory sensitivity, but significantly altered sensitivity for some basic tastants. We repeated our experimental paradigm using decaffeinated coffee and found similar results. Our results demonstrate that coffee (regular and decaffeinated) alters the subsequent perception of taste, specifically by increasing the sensitivity to sweet and decreasing the sensitivity to bitter. Our findings provide the first evidence of how coffee impacts short-term taste sensitivity and consequently the way we sense and perceive food following coffee intake—an important insight in the context of gastronomy, as well as in chemosensory testing procedures.

A novel bionic in vitro bioelectronic tongue based on cardiomyocytes and microelectrode array for bitter and umami detection

Electronic tongues (ETs) have been developed and widely used in food, beverage and pharmaceutical fields, but limited in sensitivity and specificity. In recent years, bioelectronic tongues (BioETs) integrating biological materials and various types of transducers are proposed to bridge the gap between ET system and biological taste. In this work, a bionic in vitro cell-based BioET is developed for bitter and umami detection, utilizing rat cardiomyocytes as a primary taste sensing element and microelectrode arrays (MEAs) as a secondary transducer for the first time. The primary cardiomyocytes of Sprague Dawley (SD) rats, which endogenously express bitter and umami taste receptors, were cultured on MEAs. Cells attached and grew well on the sensor surface, and syncytium was formed for potential conduction and mechanical beating, indicating the good biocompatibility of surface coating. The specificity of this BioET was verified by testing different tastants and bitter compounds. The results show that the BioET responds to bitter and umami compounds specifically among five basic tastants. For bitter recognition, only those can activate receptors in cardiomyocytes can be recognized by the BioET, and different bitter substances could be discriminated by principal component analysis (PCA). Moreover, the specific detections of two bitters (Denatonium Benzoate, Diphenidol) and an umami compound (Monosodium Glutamate) were realized with a detection limit of 10−6 M. The cardiomyocytes-based BioET proposed in this work provides a new approach for the construction of BioETs and has promising applications in taste detection and pharmaceutical study.

Altered Salivary Flow, Protein Composition, and Rheology Following Taste and TRP Stimulation in Older Adults.

Taste and smell perceptions diminish in older age, impacting upon quality of life and nutrition, yet the causes of taste loss are largely unknown. Transient receptor potential channels (TRP) found on the oral mucosa are also involved in oral sensations including cooling and burning and may contribute to the eating experience of older people. Older adults often have reduced salivary flow and the physical properties of saliva may change, but the role of saliva in oral sensations of older adults is yet to be elucidated. Here, the effect of older age on subjective (perception) and objective (stimulated salivary response) measures of TRP stimulants, odors, and basic tastants was investigated. Whole mouth saliva was collected from younger (mean age 24 years) and older adults (mean age 72 years) following stimulation of taste [mono sodium glutamate (MSG) and caffeine], olfaction (menthol), and TRP receptors (capsaicin). Participants rated perceived intensity of each stimulus, and salivary properties were assessed. Older age was associated with 15% lower umami taste and 26% lower menthol odor perception, coupled with 17% lower salivary response to MSG. Interestingly, there were no differences for perception of TRP stimulants, so chemo-sensation was not affected by age. Younger adults had four times greater elasticity (Spinnbarkeit) with MUC7 levels almost double and 66% greater resting salivary flow rate. Stimulated salivary responses in the younger group were also higher compared to the older group, with changes in protein and viscoelasticity in response to taste and TRP stimulation. These results show the impact of older age upon taste and smell sensation which may lead to changes in the physical and compositional properties of saliva in response to taste/odor stimulation. Measurement of stimulated salivary flow and rheology provides an objective measure of taste in addition to subjective perceptions which can be influenced by participant bias. Chemo-sensation may be retained with age and trigeminal stimuli such as chili could be employed in future studies to enhance meals for an age group at risk of malnutrition. Alteration in salivary properties due to advanced age could impact on ability to taste due to poor diffusion of tastants and reduced oral surface protection.

Intensity-related distribution of sweet and bitter taste fMRI responses in the insular cortex.

The human gustatory cortex analyzes the chemosensory properties of tastants, particularly the quality, intensity, and affective valence, to determine whether a perceived substance should be ingested or rejected. Among previous studies, the spatial distribution of taste intensity-related activations within the human insula has been scarcely addressed. To spatially characterize a specialized or distributed nature of the cortical responses to taste intensities, a functional magnetic resonance imaging study was performed at 3 T in 44 healthy subjects where sweet and bitter tastants were administered at five increasing concentrations and cortex-based factorial and parametric analyses were performed. Two clusters in the right middle-posterior and left middle insula were found specialized for taste intensity processing, exhibiting a highly nonlinear profile across concentrations. Multiple clusters were found activated by sweet and bitter taste stimuli at most concentrations, in the anterior, middle-posterior, and inferior portion of the bilateral insula. Across these clusters, respectively, for the right and left insula, a superior-to-inferior and an anterior-to-posterior spatial gradient for high-to-low concentrations were observed for the most responsive intensity of both tastes. These findings may gather new insights regarding how the gustatory cortex is spatially organized during the perceptual processing of taste intensity for two basic tastants.

Maternal Odor Exposure Modulates Acceptance of a Bitter Taste in Newborn and Infant Rats.

The acceptance of bitter, aversive, substances during early life is enhanced by stimulation with familiar, pre-exposed odors. Newborn rats exhibited heightened grasp responses toward an artificial nipple dispensing quinine, and drank more of this bitter solution, if concurrently stimulated with a lemon odor they had been exposed to shortly after birth. It yet unknown, however, if odors made familiar via normative developmental milestones also acquire modulatory influence upon seeking and intake of basic tastants. The current study assessed the influence of exposure to maternal odor on intake and grasp responses toward a surrogate nipple providing quinine, in 3-day (Experiment 1) or 12-day (Experiment 2) old, Wistar rat pups. The results revealed enhanced seeking and intake of the bitter solution, but not of water, in animals tested in the presence of the mother (and hence exposed to its odor cues), at both ages, compared to counterparts given either no explicit odor stimulation or stimulation to the odor of an unrelated dam. These results, obtained with a biologically relevant odor, are consistent with those previously found with a neutral, arbitrary odor. It seems that during the early stages of development, familiar odors regulate the acceptance of non-palatable, otherwise rejected, flavors.

Age-related changes of gustatory function depend on alteration of neuronal circuits.

Studies on age-related gustatory function report a reduction of the taste function, but the degeneration of the peripheral papillae alone cannot explain this reduction. In the present study, we apply psychophysics and gustatory event-related potentials (gERPs) to explore age-related differences in the processing of gustatory information as indicated by the cerebral sources of the gERP. A total of 96 subjects (47 female), subdivided into four groups with increasing age, participated in the study. After olfactory and gustatory screening for normal function, the subjects were invited to two sessions of gERP acquisition. They received a randomized combination of five isointense basic tastants that were presented at a medium level. At the same time, we recorded scalp electroencephalography (EEG) from 128 scalp locations. Psychophysical testing for smell and taste function exhibited a significant decrease with age. Topographical analyses of the EEG delineated four basic topographical maps that explained the processing of taste in the pre-decline age range, with sources inside the relevant gustatory areas. The age-related change of gustatory processing was associated with the absence of a specific map with sources inside the cerebellum and posterior insula, and the temporal broadening of a map with sources in the bilateral inferior frontal gyrus. These results confirm the hypothesis that the reduction of taste function with aging is not only due to degradation of gustatory peripheral tissues but is also related to different neural signatures in the central nervous system.

"Turn Up the Taste": Assessing the Role of Taste Intensity and Emotion in Mediating Crossmodal Correspondences between Basic Tastes and Pitch.

People intuitively match basic tastes to sounds of different pitches, and the matches that they make tend to be consistent across individuals. It is, though, not altogether clear what governs such crossmodal mappings between taste and auditory pitch. Here, we assess whether variations in taste intensity influence the matching of taste to pitch as well as the role of emotion in mediating such crossmodal correspondences. Participants were presented with 5 basic tastants at 3 concentrations. In Experiment 1, the participants rated the tastants in terms of their emotional arousal and valence/pleasantness, and selected a musical note (from 19 possible pitches ranging from C2 to C8) and loudness that best matched each tastant. In Experiment 2, the participants made emotion ratings and note matches in separate blocks of trials, then made emotion ratings for all 19 notes. Overall, the results of the 2 experiments revealed that both taste quality and concentration exerted a significant effect on participants’ loudness selection, taste intensity rating, and valence and arousal ratings. Taste quality, not concentration levels, had a significant effect on participants’ choice of pitch, but a significant positive correlation was observed between individual perceived taste intensity and pitch choice. A significant and strong correlation was also demonstrated between participants’ valence assessments of tastants and their valence assessments of the best-matching musical notes. These results therefore provide evidence that: 1) pitch–taste correspondences are primarily influenced by taste quality, and to a lesser extent, by perceived intensity; and 2) such correspondences may be mediated by valence/pleasantness.

Assessing the Role of Taste Intensity and Hedonics in Taste-Shape Correspondences.

Taste liking influences the way in which people match tastes to shapes. However, taste-shape matching cannot be explained entirely by taste hedonics. Here, we assess whether variations in taste intensity influence such crossmodal correspondences. Participants were presented with five basic tastants in two concentrations and had to rate them on roundness/angularity shape scales, as well as in terms of liking, and intensity. The results revealed that taste quality, intensity, and participants' liking of the taste significantly predicted the roundness/angularity of the tastants. The results also revealed a positive correlation between perceived intensity and roundness/angularity for each of the tastants except sweet, and a negative correlation between liking and roundness/angularity for all of the tastes. These results are discussed in terms of the mechanism(s) that underlie the crossmodal correspondence between taste and shape.

Development of Lipid Membrane Based Taste Sensors for Electronic Tongue

Abstract Artificial lipid membrane thin films using dip/drop method on gold/carbon printed electrodes have been developed and characterized. Artificial lipid membranes were prepared by using lipid/lipids, Polyvinyl chloride and plasticizers in a defined ratio. Lipid membranes for four basic tastes namely sweetness, sourness, saltiness and bitterness were prepared. The potentiometric response of the membranes was measured for basic tastants such as glucose, hydrogen chloride, sodium chloride, glutamic acid and quinine in different molar concentrations. The response shows the specificity of the membrane for the respective tastants. It has been demonstrated that the lipid membrane can directly be coated on to electrodes and used for electronic tongue applications.

Change in the hedonic value of an aversive stimulus in the presence of a pre-exposed odor

Rats exhibit a sensitive period from the time of birth until postnatal day 10 during which they develop preferences for odors even if those odors are paired with a moderately aversive stimulus. It is still unknown whether pre-exposure to an odor produces alterations on intake responses of basic tastants, and on other patterns that indicate a change in the hedonic value of reward, such as nipple grasping behavior. The current study assessed the effect of pre-exposure to an odor immediately after birth on intake responses of appetitive and aversive tastants. The objectives were to assess if 3-hour-old rats adjust their behaviors to obtain different values of appetitive and aversive rewards in the presence of a familiar odor. Specifically we wanted to determine whether the intake of saccharin or quinine, administered through the artificial nipple, increases in the presence of the familiar odor. Results showed that 3-hour-old rats differentially respond to two different concentrations of saccharin and two concentrations of quinine. In the presence of the pre-exposed odor newborn rats increased intake and grasp responses to the artificial nipple containing quinine. This effect disappeared with a higher concentration of quinine. These results suggest that the pre-exposed odor generated a change in the hedonic value of the aversive reward.

Hedonic mediation of the crossmodal correspondence between taste and shape

Crossmodal correspondences between gustatory (taste), olfactory (smell), and flavour stimuli on the one hand and visual attributes on the other have been extensively documented in recent years. For instance, people have been shown to consistently match specific tastes and flavours to particular visual shapes. That said, further research is still needed in order to clarify how and why such correspondences exist. Here, we report a series of four experiments designed to assess what drives people’s matching of visual roundness/angularity to both ‘basic’ taste names and actual tastants. In Experiment 1, crossmodal correspondences between taste names and abstract shapes were assessed. Next, the results were replicated in a larger online study (Experiment 2). Experiment 3 assessed the role of liking in the association between taste words and morphed shapes along the roundness/angularity dimension. In Experiment 4, basic tastants were mapped to the roundness/angularity dimension, while the mediating role of liking for each taste was assessed. Across the 4 experiments, participants consistently matched sweetness to roundness. What is more, people’s liking for a taste (but not their liking for imagined tastes) appeared to influence their shape matching responses. These results are discussed in terms of crossmodal correspondences, and a potential role for hedonics is outlined.

Reduced Taste Sensitivity in Congenital Blindness

Sight is undoubtedly not only important for food identification and selection but also for the modulation of gustatory sensitivity. We can, therefore, assume that taste sensitivity and eating habits are affected by visual deprivation from birth. We measured taste detection and identification thresholds of the 5 basic tastants in 13 congenitally blind and 13 sighted control subjects. Participants also answered several eating habits questionnaires, including the Food Neophobia Scale, the Food Variety Seeking Tendency Scale, the Intuitive Eating Scale, and the Body Awareness Questionnaire. Our behavioral results showed that compared with the normal sighted, blind subjects have increased thresholds for taste detection and taste identification. This finding is at odds with the superior performance of congenitally blind subjects in several tactile, auditory and olfactory tasks. Our psychometric data further indicate that blind subjects more strongly rely on internal hunger and satiety cues, instead of external contextual or emotional cues, to decide when and what to eat. We suggest that the lower taste sensitivity observed in congenitally blind individuals is due to various blindness-related obstacles when shopping for food, cooking and eating out, all of which contribute to underexpose the gustatory system to a larger variety of taste stimuli.

A Taste and Odor Sensing by Photoluminescence Responses of Luminescent Metal Organic Frameworks

The sensors of taste and odor play important roles of recognition as well as reception. In our research, the taste and odor sensing capabilities were based on the photoluminescence (PL) responses of luminescent metal-organic frameworks (MOFs). For the sensing of taste, [In(OH)(bdc)]n(bdc = 1,4-benzenedicarboxylate) and [Tb(btc)] (MOF-76, btc = benzene-1,3,5-tricarboxylate), were tested on aqueous solutions of five basic tastants such as sucrose (sweet), caffeine (bitter), citric acid (sour), sodium chloride (salty) and monosodium glutamate (umami). The photoluminescence (PL) responses of polyacrylic acid-chelated [In(OH)bdc]n and lanthanide Tb(btc) were used to demonstrate the applicability of MOF-based biomimetic tongue through: (1) identification of five tastes: sweet, bitter, sour, salty and umami, by 3-D PCA (principle component analysis) to distinguish the corresponding tastants, (2) quantification of the strength of five tastes determined by the relationships between the PL intensity and the τ scale of taste. For the sensing of odor, [In(OH)(bdc)]nand [Zn4O(bdc)3] (MOF-5) were exposed to the odorants such as cumin, cinnamon, vanillin, p-xylene, m-xylene, o-xylene, water, and ethanol. Similarly, the MOF-based biomimetic nose could distinguish the odors of the analytes based on a pattern recognition method (i.e., principal component analysis) constructed by the 2-D map of PL emission responses.