Human Sensory Test Research Articles

Relationship between the usability and physicochemical properties of triamcinolone acetonide ointments

The purpose of this study was to examine the physicochemical properties of TA ointments and conduct a human sensory test to assess the properties of those ointments. Physicochemical assessment was done via near-infrared (NIR) absorption spectroscopy, measurement of water content, microscopy, and measurement of viscoelasticity. The human sensory test examined 5 aspects (texture, cohesiveness, spreadability, smell, and feel). Three TA ointments were used: TA-A, a brand-name preparation, and TA-B and TA-C, two generics. The sensory test revealed significant differences between TA-A and TA-B and TA-C in terms of cohesiveness and spreadability. Significant differences between TA-A and TA-C and between TA-B and TA-C in terms of feel were noted. Microscopic examination revealed that TA-C had good dispersibility while TA-A and TA-B produced crystallization. NIR spectroscopy revealed differences in absorption spectra attributed to oil and water content in TAA, TA-B, and TA-C. Measurement of water content indicated water content of 0.06 ± 0.02% for TA-A, 0.08 ± 0.08% for TA-B, and 36.7 ± 1.19% for TA-C. Assessment of viscoelasticity indicated that stress decreased for all 3 ointments at 35 °C compared to that at 25 °C. TA-A and TA-B were found to have a higher percent decrease in stress than was TA-C. These findings indicate that differences in the types and content of additives caused differences in the physicochemical properties of individual ointments. In addition, differences in physicochemical properties presumably resulted in the close correlation between cohesiveness and spreadability in the sensory test.

Bitterness prediction of H1-antihistamines and prediction of masking effects of artificial sweeteners using an electronic tongue

The study objective was to quantitatively predict a drug's bitterness and estimate bitterness masking efficiency using an electronic tongue (e-Tongue). To verify the predicted bitterness by e-Tongue, actual bitterness scores were determined by human sensory testing. In the first study, bitterness intensities of eight H(1)-antihistamines were assessed by comparing the Euclidean distances between the drug and water. The distances seemed not to represent the drug's bitterness, but to be greatly affected by acidic taste. Two sensors were ultimately selected as best suited to bitterness evaluation, and the data obtained from the two sensors depicted the actual taste map of the eight drugs. A bitterness prediction model was established with actual bitterness scores from human sensory testing. Concerning basic bitter substances, such as H(1)-antihistamines, the predictability of bitterness intensity using e-Tongue was considered to be sufficiently promising. In another study, the bitterness masking efficiency when adding an artificial sweetener was estimated using e-Tongue. Epinastine hydrochloride aqueous solutions containing different levels of acesulfame potassium and aspartame were well discriminated by e-Tongue. The bitterness masking efficiency of epinastine hydrochloride with acesulfame potassium was successfully predicted using e-Tongue by several prediction models employed in the study.

Age-associated loss of selectivity in human olfactory sensory neurons

We report a cross-sectional study of olfactory impairment with age based on both odorant-stimulated responses of human olfactory sensory neurons (OSNs) and tests of olfactory threshold sensitivity. A total of 621 OSNs from 440 subjects in 2 age groups of younger (≤ 45 years) and older (≥ 60 years) subjects were investigated using fluorescence intensity ratio fura-2 imaging. OSNs were tested for responses to 2 odorant mixtures, as well as to subsets of and individual odors in those mixtures. Whereas cells from younger donors were highly selective in the odorants to which they responded, cells from older donors were more likely to respond to multiple odor stimuli, despite a loss in these subjects' absolute olfactory sensitivity, suggesting a loss of specificity. This degradation in peripheral cellular specificity may impact odor discrimination and olfactory adaptation in the elderly. It is also possible that chronic adaptation as a result of reduced specificity contributes to observed declines in absolute sensitivity.

Sweeteners interacting with the transmembrane domain of the human sweet-taste receptor induce sweet-taste synergisms in binary mixtures

Sweet enhancing effect of neohesperidin dihydrochalcone (NHDC) or cyclamate has been reported to be synergistic in human sensory tests. However, little is known about whether these synergisms are caused by the mechanism mediated by the human sweet-taste receptor. Here, we examined the sweetness intensity of sweet tastant mixtures by measuring the responses of cultured cells stably expressing the human sweet-taste receptor. The results showed that the cell response to sucrose was synergistically potentiated by the addition of NHDC or cyclamate. Moreover, a point mutation in the transmembrane domain of hT1R3 almost completely eliminated the enhancing effects of NHDC and cyclamate. These results suggest that ligand–receptor interactions in the transmembrane domain of hT1R3 are necessary for NHDC and cyclamate to elicit the synergistic potentiation of the receptor activation. Our results may provide the foundation of a molecular basis for receptor-based synergisms of sweet tastes in mixtures of diverse sweet substances.

Identification and Modulation of the Key Amino Acid Residue Responsible for the pH Sensitivity of Neoculin, a Taste-Modifying Protein

Neoculin occurring in the tropical fruit of Curculigo latifolia is currently the only protein that possesses both a sweet taste and a taste-modifying activity of converting sourness into sweetness. Structurally, this protein is a heterodimer consisting of a neoculin acidic subunit (NAS) and a neoculin basic subunit (NBS). Recently, we found that a neoculin variant in which all five histidine residues are replaced with alanine elicits intense sweetness at both neutral and acidic pH but has no taste-modifying activity. To identify the critical histidine residue(s) responsible for this activity, we produced a series of His-to-Ala neoculin variants and evaluated their sweetness levels using cell-based calcium imaging and a human sensory test. Our results suggest that NBS His11 functions as a primary pH sensor for neoculin to elicit taste modification. Neoculin variants with substitutions other than His-to-Ala were further analyzed to clarify the role of the NBS position 11 in the taste-modifying activity. We found that the aromatic character of the amino acid side chain is necessary to elicit the pH-dependent sweetness. Interestingly, since the His-to-Tyr variant is a novel taste-modifying protein with alternative pH sensitivity, the position 11 in NBS can be critical to modulate the pH-dependent activity of neoculin. These findings are important for understanding the pH-sensitive functional changes in proteinaceous ligands in general and the interaction of taste receptor–taste substance in particular.

Development of a New Disintegration Method for Orally Disintegrating Tablets

Recently, the focus has been on the importance of assessing the oral disintegrative properties of orally disintegrating tablets (ODTs). In particular, in the development stages and the quality control field of ODT products, a physical assessment method which easily measures oral disintegrative properties is desired. For this reason, we developed a new disintegration test method (Kyoto-model disintegration method or KYO method), which is useful to predict the oral disintegrative properties of an ODT easily, and examined the availability of the method. In the KYO method, ODT samples were classified in terms of their water permeability, and a moderate water volume was decided. Subsequently, the disintegrative properties were assessed with the newly proposed method. For 25 commercial prescription ODTs used as samples, a good correlation was shown between the results of a human sensory test by five healthy male volunteers and the results using the KYO method. Furthermore, the KYO method could evaluate time-dependent changes in ODT samples. On the other hand, no correlation was observed between the Japanese Pharmacopeia disintegration test and the human sensory test. These results suggested that the KYO method reflected the disintegration nature of the ODTs in the oral cavity, and could easily be applied to development stages and the quality control field of ODT products.

Sweet and bitter constituents of Wilbrandia species

Two novel cucurbitane glycosides, wilbrandisides A and B were isolated as sweet-taste substances from the root of Wilbrandia species ( Cucurbitaceae) along with seven known cucurbitane glycosides. Their structures were determined by spectroscopic means, including two-dimensional NMR experiments. Their sweet-taste properties were evaluated by a human sensory panel test. Consequently, wilbrandiside A was shown to be 28 times sweeter than sucrose and was the compound having the most potent sweet taste of all the cucurbitane glycosides isolated from this plant.

Relationship between Peripheral Receptor Code and Perceived Odor Quality

The discrimination of thousands of odorants is mediated by several hundred olfactory receptors (ORs). It is generally accepted that the main strategy in encoding odor quality is a combinatorial receptor code scheme, in which odorants are discriminated by different sets of ORs. In the present study, we classified 12 test odorants by their receptor codes and perceived odor qualities to examine whether odorants showing similar receptor codes are also similar in their odor qualities. Similarities of receptor codes between odorants were estimated by the overlapping responses of murine isolated olfactory sensory neurons. In contrast, we conducted a human sensory test to classify the test odorants according to their odor qualities. Despite the difference in species, the groupings of the test odorants were well conserved between receptor code and odor quality. These findings indicate that odorants that are discriminated by murine receptor codes are perceived as different odors by humans and further suggest that similarity of receptor codes correlates with that of odor quality, at least in our test odorants at the concentrations tested.

Suppression of Bitterness and Improvement of Palatability of Commercial Prednisolone Powder

The aim of the study was to suppress the bitterness and improve the palatability of pediatric prednisolone powder (PP) by the addition of simple sucrose syrup (SS) and various beverages and foods. Bitterness suppression was evaluated using the human gustatory sensory test. The suppression of the bitterness and improvement of palatability of PP by addition of SS solutions was investigated using standard taste substances: sucrose for sweetness, tartaric acid for sourness, and sodium chloride as saltiness. Dilution with SS solutions of up to 50% (w/w) was successful in bitterness-suppression and improvement of palatability, but at 80% (w/w) SS, the palatability of the diluted solution was reduced. The kinematic viscosities of SS solutions were therefore evaluated using the Uberorde viscosity meter, to see whether the high viscosity of the more concentrated solutions was responsible for the reduced palatability. The kinematic viscosity of the 80% SS was 16.60 mm(2)/s. Judging from above information, the palatability might become worse when the kinematic viscosity of syrup exceeded 15 mm(2)/s. Finally, the ability of various beverages and foods with low viscosity to suppress the bitterness and improve the palatability of PP were examined. The additions of orange juice or a carbonated lemon drink to simple syrup solution were most effective in suppressing bitterness and improving palatability of PP.

Odor approximation of fruit flavors using a QCM odor sensing system

Odor approximations of orange and melon flavors were performed using an array of quartz crystal microbalance (QCM) odor sensors coated with different materials, such as lipids and stationary phase materials of gas chromatography (GC). The steady state sensor responses to single flavor components were measured and the data were used to estimate the important odor components by means of a computational two-level quantization method. From these results, the experimental approximations using the steady state sensor responses and principal component analysis (PCA) were performed. In both cases, orange and melon flavors, it was possible to approximate the recipes with only three odor components. Moreover, the similarities between the approximated odors and the original ones were evaluated by a human sensory test. It was found that these similarities were high, especially in the case of orange flavor.

Evaluation of the Disintegration Properties of Commercial Famotidine 20 mg Orally Disintegrating Tablets Using a Simple New Test and Human Sensory Test

The purpose of this study was to demonstrate the usefulness and broad-applicability of a simple disintegration test method for orally disintegrating tablets (ODT). Eight types of commercial famotidine 20 mg orally disintegrating tablets with different physical properties (formulation, manufacturing method, tablet weight, shape, diameter, thickness, etc.), were used. Disintegration times of these tablets were evaluated employing human sensory test, conventional disintegration test, and the new proposed disintegration test. The human sensory test was performed in 5 healthy volunteers. In the conventional disintegration test, the disintegration apparatus described in the Japanese Pharmacopeia (JP 1(st)) was used. Our proposed new test which is characterized by a rotating shaft with a low weight (10, 15 g) and rotation speed (10, 25, 50 rpm) was evaluated using tablets with and without storage under severe conditions (60 degrees C/75%RH for 1 week). The disintegration times of famotidine 20 mg orally disintegrating tablets in human sensory test varied from 9 to 32 s. In contrast, disintegration times in the conventional test were prolonged to over 300 s. Disintegration times in the new proposed test were close to those in human sensory test. Especially, when the new test was conducted with 15 or 10 g weight and 25 rpm, the slope (human sensory test vs. new proposed test) was almost 1. We were able to demonstrate that the new proposed test was useful to estimate the actual human disintegration time.

Usefulness of Cataplasm Improving the Quality of Life of Patients

Cataplasm containing anti-inflammatory and analgestic drug, ketoprofen, was developed. Cataplasm containing ketoprofen features the cross-linking network between aluminum and sodium polyacrylate and is a swollen hydrogel. Cataplasm can contain large amount of drug, water and other additives. Ketoprofen dispersed as microemulsions in the cataplasm is easily released from cataplasm and absorbed into the skin. Adhesion properties between cataplasms and between cataplasm and hairless mice skin were evaluated using phosphor-bronze thin plate technique. Skin-cataplasm adhesion force and cataplasm-cataplasm separation force are in good agreement with human sensory test. The diseased part was also cooled and moistured by cataplasm. It was found that cataplasm containing ketoprofen is a friendly formulation for patients.

Evaluation of 'Fuyu' Persimmon Texture by a New Parameter, "Sharpness index"

The texture of persimmon (Diospyros kaki Thunb. ‘Fuyu’), stored under 40, 60, and 100% relative humidity (RH), was evaluated by an acoustic measurement of crispness (AMC), a laser Doppler vibrometer (LDV), and human sensory test. An AMC probe with conical tip to which a piezoelectric film attached to its proximal end is inserted into mesocarp tissue and the acoustic vibration up to 10 kHz recorded. The signal is transformed to a frequency spectrum by a fast Fourier transformation. Texture parameter, “Sharpness index”, of a persimmon fruit is calculated by summation of signal intensities over the spectrum of AMC data; the high frequency intensities are enhanced to compensate for the limited human hearing capacity. “Sharpness index” significantly correlated with three sensory variables, smoothness, hardness, and crispness, for fruits kept at 100% RH condition. When partial least square (PLS) method was applied to AMC spectrum data to simulate the sensory variables, the spectrum data could relate to the three sensory variables under 60 and 100% RH, but not under 40% RH. Furthermore, PLS analysis of LDV spectrum data of a non-destructive method that evaluates hardness of persimmon fruit also correlated significantly to the three sensory variables in the 60 and 100% RH treatment.

Absorption of volatile compounds in honey from stored spices

SUMMARYSpices and coffee stored in food containers result in detectable volatile compounds in honey subsequently stored in these containers. These ‘off-flavours’ are bound to the plastic lining inside the lid and later contaminate the honey. The kind, number and concentration of these compounds depend on what has been stored in the container. Honeydew honey was used in this study. Tea did not affect the aromatic profile of honey, whereas coffee resulted in one volatile compound in honey, peppermint two, sage three, cinnamon four, oregano eight, and basil and cinnamon nine. In this study we used the purge and trap gas chromatographer/mass spectrometer system to identify the volatile compounds, as well as human sensory tests to evaluate the ability of the consumer to perceive off-flavours in honey.

Recording and reproducing citrus flavors using odor recorder

Despite high significance of the sense of smell, the technique of recording and reproducing the olfactory modality was hardly investigated. The odor recorder developed by our group enables electronic recording of the odors and their reproduction at any time and at properly equipped place. The odor recording technique is expected to be useful in many fields such as virtual environments and e-commerce. To realize the future application of the odor recorder, the range of flavors to be handled by the instrument has to be significantly expanded. However, the expansion has to meet the constraint of reasonable number of odor components. One way to achieve that is using the approximation technique with significant reduction of the flavor components. The alternative way could be blending the complex mixtures of odorants treated as single components. In the present study, we focused on investigating both approaches. In the first part of experiment, we successfully recorded the typical orange flavor, approximating the smell with only 3 of 14 components. Subsequently performed human sensory tests (triangle test) confirmed similarity of reproduced flavor and the target one. In the second part of the experiment, three binary mixtures of essential oils extracted from citrus fruits were successfully recorded using the odor recorder. Results of both parts of the study allowed further expansion of the applicable range of flavors for odor recorder.

A new method for disintegration studies of rapid disintegrating tablet.

The aim of this study was to develop a simple and suitable disintegration method specific for rapid disintegrating tablets (RDTs). The new disintegration method that we propose employs a rotary shaft to exert mechanical pressure on the RDT. To assess our method, we manufactured several placebo RDTs and exposed them to severe storage conditions (60 degrees C/75%RH for 1 week) in order to obtain RDTs with a wide range of disintegration times. These placebo RDTs were utilized to compare the disintegration times obtained by several methods, including the proposed method. As expected, the disintegration time of the placebo RDTs in human sensory test varied widely. The disintegration times determined by the conventional disintegration test were in good correlation to those in human sensory test, but the slope was far from 1 (0.241). There was no correlation between the disintegration time of RDTs in human sensory test and those determined by the conventional dissolution test. In contrast, we acquired good correlation between the disintegration times obtained with the new method and those in human sensory test, and the slope was very close to 1 (0.858). We attribute this to the use of mechanical stress in the new method, similar to that the RDT is subject to in the oral cavity. We therefore concluded that the proposed method was suitable for the measurement of the disintegration time of RDTs. This new method might provide a valuable approach for the establishment of the official disintegration test for RDTs in the future.

Fundamental study of odor recorder for multicomponent odor using recipe exploration method based on singular value decomposition

A new method for the odor recorder, electronically recording the recipe of odors or scents made up of many components, was proposed. Although apple flavors have been recorded with a mixture of five components using the odor recorder in previous work, the number of odor components should be increased to expand the applicable range of odors. Since the collinearity problem of the odor sensor array became apparent with the increase of components, a new method based on variable transformation using singular value decomposition was developed in this paper, to extract the effective subspace of the sensor outputs for recipe exploration. As a result, the sensor-array response pattern of the reproduced odor, with the eight-component recipe, almost agreed with that of the target apple flavor. Furthermore, human sensory tests revealed that the smell of the approximated odor was identical to that of the target flavor.

Study of recording apple flavor using odor recorder with five components

The odor recorder has been developed using the odor sensing system based on the active sensing method to electronically record odors and reproduce them anytime and anywhere. The recorder developed in this paper has capability of recording the target odor, the mixture of five odor components, using the odor sensor array composed of quartz crystal microbalance sensors. The difference between the sensor response patterns of the recipe and target odors was minimized so that the recipe of the five components for the target odor was determined. In this paper, the method of selecting the most appropriate sensors to record odors was investigated based on the condition number of the sensor array sensitivity matrix. Moreover, the method of determining the parameters of the odor-recording algorithm was studied. As a result, several apple flavors composed of the five components were successfully recorded. Furthermore, the typical apple flavor composed of nine components was approximated using the mixture of the five components. The approximation result by the sensing system was successfully verified by the human sensory test.

Odor recorder for multi-component odor using two-level quantization method

A new algorithm to electronically record an odor composed of the mixture of many components using the odor sensing system was proposed. Since the human impression on the odor mostly depends on the kinds of key components rather than the accurate mixture composition, the odor was approximated with the combination of several components. Moreover, the efficient method to explore the recipe for the odor approximation with the combination of many components was established. Then, the recipe of an apple flavor was recorded using the proposed method and was evaluated by the human sensory test. As a result, it was found that the odor approximated with up to eight components was close to the target apple flavor. Furthermore, it was confirmed that the response pattern of the QCM (quartz crystal microbalance) odor sensor array was a good indicator of the odors detected by human olfaction. The proposed method was useful to realize the odor recorder with many odor components.

Fuzzy-neuro LVQ and its comparison with fuzzy algorithm LVQ in artificial odor discrimination system

Abstract The human sensory test is often used for obtaining the sensory quantities of odors, however, the fluctuation of results due to the expert's condition can cause discrepancies among panelists. Authors have studied the artificial odor discrimination system using a quartz resonator sensor and a back-propagation neural network as the recognition system, however, the unknown category of odor is always recognized as the known category of odor. In this paper, a kind of fuzzy algorithm for learning vector quantization (LVQ) is developed and used as a pattern classifier. In this type of fuzzy LVQ, the neuron activation is derived through fuzziness of the input data, so that the neural system could deal with the statistics of the measurement error directly. During learning, the similarity between the training vector and the reference vectors are calculated, and the winning reference vector is updated by shifting the central position of the fuzzy reference vector toward or away from the input vector, and by modifying its fuzziness. Two types of fuzziness modifications are used, i.e., a constant modification factor and a variable modification factor. This type of fuzzy-neuro (FN) LVQ is different in nature from fuzzy algorithm (FA) LVQ, and in this paper, the performance of FNLVQ network is compared with that of FALVQ in an artificial odor recognition system. Experimental results show that both FALVQ and FNLVQ could provide high recognition probability in determining various known categories of odors, however, the FNLVQ neural system has the ability to recognize the unknown category of odor that could not be recognized by the FALVQ neural system.