119 results on '"Kiyoshi Toko"'
Search Results
2. Identification of the Principle of Taste Sensors to Detect Non-Charged Bitter Substances by
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Misaki, Ishida, Haruna, Ide, Keishiro, Arima, Zeyu, Zhao, Toshiro, Matsui, and Kiyoshi, Toko
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Polymers ,Caffeine ,Proton Magnetic Resonance Spectroscopy ,Taste ,Membrane Potentials - Abstract
A taste sensor with lipid/polymer membranes is attracting attention as a method to evaluate taste objectively. However, due to the characteristic of detecting taste by changes in membrane potential, taste sensors cannot measure non-charged bitter substances. Many foods and medicines contain non-charged bitter substances, and it is necessary to quantify these tastes with sensors. Therefore, we have been developing taste sensors to detect bitter tastes caused by non-charged substances such as caffeine. In previous studies, a sensor for detecting bitterness caused by caffeine and theobromine, theophylline, was developed, using a membrane modified with hydroxybenzoic acid (HBA) as the sensing part. The sensor was designed to form intramolecular hydrogen bonds (H-bonds) between the hydroxy group and carboxy group of HBA and to successively cause the intermolecular H-bonds between HBA and caffeine molecules to be measured. However, whether this sensing principle is correct or not cannot be confirmed from the results of taste sensor measurements. Therefore, in this study, we explored the interaction between HBA and caffeine by
- Published
- 2022
3. Effect of Hydroxybenzoic Acids on Caffeine Detection Using Taste Sensor with Lipid/Polymer Membranes
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Zeyu Zhao, Misaki Ishida, Takeshi Onodera, and Kiyoshi Toko
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taste sensor ,lipid/polymer membrane ,hydroxybenzoic acids ,caffeine detection ,Polymers ,Caffeine ,Taste ,Hydroxybenzoates ,Electrical and Electronic Engineering ,Biochemistry ,Instrumentation ,Lipids ,Atomic and Molecular Physics, and Optics ,Analytical Chemistry - Abstract
A taste sensor with lipid/polymer membranes can objectively evaluate taste. As previously reported, caffeine can be detected electrically using lipid/polymer membranes modified with hydroxybenzoic acids (HBAs). However, a systematic understanding of how HBAs contribute to caffeine detection is still lacking. In this study, we used various HBAs such as 2,6–dihydroxybenzoic acid (2,6–DHBA) to modify lipid/polymer membranes, and we detected caffeine using a taste sensor with the modified membranes. The effect of the concentrations of the HBAs on caffeine detection was also discussed. The results of the caffeine detection indicated that the response to caffeine and the reference potential measured in a reference solution were affected by the log P and pKa of HBAs. Furthermore, the taste sensor displayed high sensitivity to caffeine when the reference potential was adjusted to an appropriate range by modification with 2,6–DHBA, where the slope of the change in reference potential with increasing 2,6–DHBA concentration was steep. This is helpful in order to improve the sensitivity of taste sensors to other taste substances, such as theophylline and theobromine, in the future.
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- 2022
4. Recent development of taste sensors.
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Kiyoshi TOKO
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TASTE receptors ,TASTE ,LOW calorie foods ,DETECTORS ,TASTE testing of food ,FOOD service - Abstract
The first taste sensor was developed 30 years ago, and its use has become widespread in the food and pharmaceutical industries. Numerous efforts have been made to improve taste sensor technology since that time. Now, over 600 taste sensors are used around the world to quantify and visualize the taste of food. In this article, we first explain the mechanisms underlying the operation of taste sensors and how they respond to the five basic sensations of taste. A taste map of beers that presents their taste in a visual manner will be introduced as a typical application of the taste sensors used in the food industry. We then discuss the ability of the taste sensor to detect taste interactions, such as bitterness-suppressing effects as well as attempts to produce tasty low-calorie foods. Recent attempts to visualize personal preferences and the dynamic changes in the taste of food during chewing using the taste sensor are also explained. The environment surrounding taste sensors and the taste sensors themselves have progressed considerably, with new food services appearing constantly. We are entering an era where we can increase our enjoyment of eating. [ABSTRACT FROM AUTHOR]
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- 2023
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5. Reusability Enhancement of Taste Sensor Using Lipid Polymer Membranes by Surfactant Cleaning Treatment
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Kiyoshi Toko, Yusuke Tahara, Hidekazu Ikezaki, Yapeng Yuan, Xiao Wu, and Masaaki Habara
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Taste ,Chemistry ,Hydrochloride ,010401 analytical chemistry ,Combined use ,Synthetic membrane ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Residue (chemistry) ,Adsorption ,Pulmonary surfactant ,Chemical engineering ,Electrical and Electronic Engineering ,Instrumentation ,Reusability - Abstract
The aim of our study was to enhance the reusability of a taste sensor by increasing the efficiency of the cleaning process. In this paper, we proposed a surfactant cleaning method for two types of bitterness sensor using lipid polymer membranes with high hydrophobicity. To select suitable surfactants for cleaning, the usability of four types of surfactant with different polarities and ionicities was evaluated. Among these surfactants, the anionic surfactant linear alkylbenzene sulfonate (LAS) showed no impact on the initial membrane potential and completely removed residue substances of high-concentration quinine hydrochloride adsorbed on the bitterness sensor used for hydrochloride salts. On the other hand, the amphoteric surfactant lauryl dimethylaminoacetic acid (LDA) showed no impact on the initial membrane potential and almost completely removed residue substances of high-concentration iso- $\alpha $ acid adsorbed on the bitterness sensor used for acidic bitter materials. Moreover, we found that the combined use of the conventional cleaning solution and LDA acid solution in turn greatly improved the reusability of an astringency sensor in multiple measurements of black tea.
- Published
- 2020
6. Taste Sensor: Electronic Tongue with Lipid Membranes
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Rui Yatabe, Yusuke Tahara, Xiao Wu, and Kiyoshi Toko
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Taste ,Chemistry ,Electronic tongue ,010401 analytical chemistry ,Biosensing Techniques ,02 engineering and technology ,Umami ,Sweetness ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Membrane Lipids ,Membrane ,Biomimetics ,Humans ,Gustatory system ,Electronic Nose ,0210 nano-technology ,Biological system - Abstract
Taste is of five basic types, namely, sourness, saltiness, sweetness, bitterness and umami. In this review, we focus on a potentiometric taste sensor that we developed and fabricated using lipid polymer membranes. The taste sensor can measure the taste perceived by humans and is called an electronic tongue with global selectivity, which is the property to discriminate taste qualities and quantify them without discriminating each chemical substance. This property is similar to the gustatory system; hence, the taste sensor is a type of biomimetic device. In this paper, we first explain the sensing mechanism of the taste sensor, its application to beer evaluation and the measurement mechanism. Second, results recently obtained are introduced; i.e., the application of the senor to high-potency sweeteners and the improvement of the bitterness sensor are explained. Last, quantification of the bitterness-masking effect of high-potency sweeteners is explained using a regression analysis based on both the outputs of bitterness and sweetness sensors. The taste sensor provides a biomimetic method different from conventional analytical methods.
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- 2019
7. Electrical Properties of Two Types of Membrane Component Used in Taste Sensors
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Zhanyi Xiang, Yifei Jing, Hidekazu Ikezaki, and Kiyoshi Toko
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Chemical technology ,Sodium ,taste sensor ,lipids ,dissociation of H+ ,cation selectivity ,membrane resistance ,Hofmeister series ,TP1-1185 ,Lithium ,Biochemistry ,Atomic and Molecular Physics, and Optics ,Article ,Analytical Chemistry ,Cations ,Taste ,Electrical and Electronic Engineering ,Instrumentation ,Electrodes - Abstract
The lipid phosphoric acid di-n-decyl ester (PADE) has played an important role in the development of taste sensors. As previously reported, however, the concentration of PADE and pH of the solution affected the dissociation of H+, which made the measurement results less accurate and stable. In addition, PADE caused deterioration in the response to bitterness because PADE created the acidic environment in the membrane. To solve these problems, our past study tried to replace the PADE with a completely dissociated substance called tetrakis [3,5-bis (trifluoromethyl) phenyl] borate sodium salt dehydrate (TFPB) as lipid. To find out whether the two substances can be effectively replaced, it is necessary to perform an in-depth study on the properties of the two membranes themselves. In this study, we fabricated two types of membrane electrodes, based on PADE or TFPB, respectively, using 2-nitrophenyl octyl ether (NPOE) as a plasticizer. We measured the selectivity to cations such as Cs+, K+, Na+ and Li+, and also the membrane impedance of the membranes comprising PADE or TFPB of the different concentrations. As a result, we found that any concentration of PADE membranes always had low ion selectivity, while the ion selectivity of TFPB membranes was concentration-dependent, showing increasing ion selectivity with the TFPB concentrations. The ion selectivity order was Cs+>K+>Na+>Li+. The hydration of ions was considered to participate in this phenomenon. In addition, the membrane impedance decreased with increasing PADE and TFPB concentrations, while the magnitudes differed, implying that there is a difference in the dissociation of the two substances. The obtained results will contribute to the development of novel receptive membranes of taste sensors.
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- 2021
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8. Visualization of flavor of sake using taste sensor and gas chromatography‐mass spectrometry
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Miyo Hirata, Keiichi Mitani, Kiyoshi Toko, Yoichiro Kanno, Takeshi Onodera, and Shiho Shirota
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Taste ,Chromatography ,Computer Networks and Communications ,Chemistry ,Applied Mathematics ,Signal Processing ,General Physics and Astronomy ,Statistical analysis ,Electrical and Electronic Engineering ,Gas chromatography–mass spectrometry ,Flavor ,Visualization - Published
- 2020
9. Development of Taste Sensor to Detect Non-Charged Bitter Substances
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Masaaki Habara, Yusuke Tahara, Kiyoshi Toko, Hidekazu Ikezaki, Jumpei Yoshimatsu, Misaki Ishida, Takahiro Uchida, Honami Kojima, Miyako Yoshida, and Saeri Ikegami
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Taste ,Carboxylic acid ,030303 biophysics ,Potentiometric titration ,Synthetic membrane ,Biosensing Techniques ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,bitterness ,Article ,Analytical Chemistry ,Membrane Potentials ,03 medical and health sciences ,chemistry.chemical_compound ,lipid/polymer membrane ,Caffeine ,medicine ,Humans ,Theophylline ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Theobromine ,chemistry.chemical_classification ,0303 health sciences ,allostery ,010401 analytical chemistry ,bitterness sensor ,Combinatorial chemistry ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,non-charged substances ,Membrane ,chemistry ,taste sensor ,medicine.drug - Abstract
A taste sensor with lipid/polymer membranes is one of the devices that can evaluate taste objectively. However, the conventional taste sensor cannot measure non-charged bitter substances, such as caffeine contained in coffee, because the taste sensor uses the potentiometric measurement based mainly on change in surface electric charge density of the membrane. In this study, we aimed at the detection of typical non-charged bitter substances such as caffeine, theophylline and theobromine included in beverages and pharmaceutical products. The developed sensor is designed to detect the change in the membrane potential by using a kind of allosteric mechanism of breaking an intramolecular hydrogen bond between the carboxy group and hydroxy group of aromatic carboxylic acid (i.e., hydroxy-, dihydroxy-, and trihydroxybenzoic acids) when non-charged bitter substances are bound to the hydroxy group. As a result of surface modification by immersing the sensor electrode in a modification solution in which 2,6-dihydroxybenzoic acid was dissolved, it was confirmed that the sensor response increased with the concentration of caffeine as well as allied substances. The threshold and increase tendency were consistent with those of human senses. The detection mechanism is discussed by taking into account intramolecular and intermolecular hydrogen bonds, which cause allostery. These findings suggest that it is possible to evaluate bitterness caused by non-charged bitter substances objectively by using the taste sensor with allosteric mechanism.
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- 2020
10. A Quantitative Method for Acesulfame K Using the Taste Sensor
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Yuanchang Liu, Yusuke Tahara, Xiao Wu, Kiyoshi Toko, and Hidekazu Ikezaki
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Taste ,high-potency sweeteners ,acesulfame K ,030303 biophysics ,Analytical chemistry ,Acesulfame potassium ,sweetness sensor ,lcsh:Chemical technology ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Analysis method ,0303 health sciences ,010401 analytical chemistry ,food and beverages ,lipid polymer membrane ,Sweetness ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,chemistry ,taste sensor ,Nonlinear regression - Abstract
We have developed a method to quantify the sweetness of negatively charged high-potency sweeteners coexisting with other taste substances. This kind of sweetness sensor uses lipid polymer membranes as the taste-sensing part. Two types of outputs have been defined in the measurement of the taste sensor: one is the relative value and the other is the CPA (the change in membrane potential caused by adsorption) value. The CPA value shows a good selectivity for high-potency sweeteners. On the other hand, the relative value is several times higher than the CPA value, but the relative value is influenced by salty substances. In order to obtain both high sensitivity and selectivity, we established a model for predicting the concentration of sweeteners with a nonlinear regression analysis method using the relative values of both the sweetness sensor and the saltiness sensor. The analysis results showed good correlations with the estimated concentration of acesulfame potassium coexisting with salty substances, as represented by R2 = 0.99. This model can correspond well to the prediction of acesulfame K in a concentration of 0.2&ndash, 0.7 mM, which is commonly used in food and beverages. The results obtained in this paper suggest that this method is useful for the evaluation of acesulfame K using the taste sensors.
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- 2019
11. Bitterness compounds in coffee brew measured by analytical instruments and taste sensing system
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Misako Kakiuchi, Kazunari Miyake, Kazuya Iwai, Hidekazu Ikezaki, Yusuke Tahara, Tsukasa Kobayashi, Yusaku Narita, Shingo Ariki, Xiao Wu, Taku Hanzawa, Hirofumi Fujimoto, Taiji Fukunaga, and Kiyoshi Toko
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Taste ,Nicotinamide ,Chemistry ,010401 analytical chemistry ,technology, industry, and agriculture ,food and beverages ,04 agricultural and veterinary sciences ,General Medicine ,Coffee ,040401 food science ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,0404 agricultural biotechnology ,stomatognathic system ,Multivariate Analysis ,Food science ,Latent structure ,Sensing system ,Food Analysis ,Food Science - Abstract
We investigated the bitter compounds in coffee brews using multivariate analysis of the data obtained from analytical instrument and electronic taste sensor experiments. Coffee brews were prepared from coffee beans roasted to four different degrees. Each brew was fractionated into four fractions by liquid-liquid extraction. The relative amounts of 30 compounds in each fraction were analyzed by analytical instruments, and the bitterness response value of each fraction was analyzed by a taste sensor. Candidate bitter compounds in the coffee brews were identified with reference to their variable importance in projection and by coefficient of projection to latent structure regression (PLS-R) analysis. PLS-R analysis suggested that nicotinic acid, l-lactic acid, and nicotinamide contributed to the bitterness of the coffee brews. In fact, the coffee brews with added nicotinic acid, l-lactic acid, and nicotinamide had an increased bitterness response value compared to those without.
- Published
- 2021
12. Quantitative prediction of bitterness masking effect of high-potency sweeteners using taste sensor
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Yusuke Tahara, Tamami Haraguchi, Hidekazu Ikezaki, Miyako Yoshida, Rui Yatabe, Xiao Wu, Hideya Onitake, Takahiro Uchida, and Kiyoshi Toko
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Masking (art) ,Taste ,Aspartame ,Chemistry ,digestive, oral, and skin physiology ,010401 analytical chemistry ,Metals and Alloys ,food and beverages ,02 engineering and technology ,Sweetness ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Quinine Hydrochloride ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,stomatognathic system ,Materials Chemistry ,Food science ,Electrical and Electronic Engineering ,0210 nano-technology ,Instrumentation ,psychological phenomena and processes - Abstract
A taste sensor based on lipid/polymer membranes has been reported being possible to detect the masking of bitter substances or masking on bitterness receptors (physical masking or biochemical masking). However, it was difficult to express the bitterness suppression by sweeteners, which is decided by the balance of substances produced in human’s brain (functional masking). High-potency sweeteners are one of the sweeteners used for bitterness-masking in food and pharmaceutical industry. The objective of this study is to evaluate the bitterness-masking effect of high-potency sweeteners using the taste sensor. A bitterness sensor was used to evaluate the bitterness of quinine hydrochloride, and sweetness sensors for high-potency sweeteners were used to evaluate the sweetness of aspartame and saccharine sodium. The sensory evaluation was also carried out to examine the bitterness suppression effect of high-potency sweeteners. The bitterness-prediction formulas were proposed with the aid of a model regression analysis using two outputs from the bitterness sensor and the sweetness sensor for high-potency sweeteners. As a result, the predicted bitterness showed a good correlation with the human taste when aspartame or saccharine sodium was added to quinine hydrochloride. Thus, this study provided an effective method to evaluate the bitterness suppressed by high-potency sweeteners.
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- 2016
13. Taste and Odor Sensors
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Kiyoshi Toko
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Taste ,Odor ,Chemistry ,Food science - Published
- 2016
14. Quantification of bitterness of coffee in the presence of high-potency sweeteners using taste sensors
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Xiao Wu, Yusuke Tahara, Taiji Fukunaga, Shingo Ariki, Kazuya Iwai, Kazunari Miyake, Hirofumi Fujimoto, Taku Hanzawa, Hidekazu Ikezaki, Yusaku Narita, Misako Kakiuchi, Kiyoshi Toko, and Tsukasa Kobayashi
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Taste ,Metals and Alloys ,Acesulfame potassium ,food and beverages ,02 engineering and technology ,Sweetness ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,stomatognathic system ,chemistry ,Materials Chemistry ,Potency ,Food science ,Electrical and Electronic Engineering ,0210 nano-technology ,Instrumentation ,psychological phenomena and processes ,Roasting - Abstract
Electronic tongues have been identified as useful tools for quantifying the taste of food and beverages. However, the bitterness evaluation of coffee in the presence of high-potency sweeteners has not been performed yet. In this study, we investigated an approach to quantify the bitterness of coffee with different roasting degrees and the sweetness of acesulfame potassium (Ace K) added to the coffee using taste sensors with lipid polymer membranes. A formula for predicting coffee bitterness with the addition of Ace K was proposed using the responses of a bitterness sensor and a sweetness sensor. We found that the predicted coffee bitterness showed a good correlation with human taste.
- Published
- 2020
15. Development of a Sensor with a Lipid/Polymer Membrane Comprising Na+ Ionophores to Evaluate the Saltiness Enhancement Effect
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Hiroyuki Sano, Kiyoshi Toko, Xiao Wu, Yusuke Tahara, Hidekazu Ikezaki, Futa Nakatani, Tomofumi Ienaga, Yuki Muto, and Yuya Kaneda
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saltiness sensor ,Taste ,Sodium ,Synthetic membrane ,Ionophore ,chemistry.chemical_element ,Salt (chemistry) ,02 engineering and technology ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,lipid/polymer membrane ,Electrical and Electronic Engineering ,Instrumentation ,ionophore ,chemistry.chemical_classification ,Chromatography ,Chemistry ,saltiness enhancement effect ,010401 analytical chemistry ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Membrane ,Tartaric acid ,taste sensor ,0210 nano-technology ,Citric acid - Abstract
The saltiness enhancement effect is the effect whereby saltiness is enhanced by adding specific substances to salt (sodium chloride). Since this effect can be used in the development of salt-reduced foods, a method to objectively evaluate the saltiness with this effect is required. A taste sensor with lipid/polymer membranes has been used to quantify the taste of food and beverages in recent years. The sensor electrodes of this taste sensor have the feature of selectively responding to each of the five basic tastes, which is realized by the lipid/polymer membranes. In this study, we developed a new saltiness sensor based on the lipid/polymer membrane with the aim of quantifying the saltiness enhancement effect. In addition to the conventional components of a lipid, plasticizer, and polymer supporting reagent, the membrane we developed comprises ionophores, which selectively capture sodium ions. As a result, the response of the sensor increased logarithmically with the activity of NaCl in measured samples, similarly to the taste response of humans. In addition, all of the sensor responses increased upon adding saltiness-enhancing substances, such as citric acid, tartaric acid and branched-chain amino acids (BCAAs), to NaCl samples. These findings suggest that it is possible to quantify the saltiness enhancement effect using a taste sensor with lipid/polymer membranes.
- Published
- 2019
16. Effects of Manufacturing Processing Conditions on Retronasal-Aroma Odorants from a Milk Coffee Drink
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Michio, Ikeda, Masayuki, Akiyama, Yuta, Hirano, Kazuhiro, Miyaji, Yasunori, Sugawara, Yuriko, Imayoshi, Hisakatsu, Iwabuchi, Takeshi, Onodera, and Kiyoshi, Toko
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Milk ,Food Handling ,Taste ,Odorants ,Olfactometry ,Temperature ,Animals ,Humans ,Hydrogen-Ion Concentration ,Coffee ,Gas Chromatography-Mass Spectrometry - Abstract
To develop a ready-to-drink (RTD) milk coffee that retains the original coffee flavor, the effects of manufacturing processing conditions on retronasal-aroma (RA) odorants were investigated by gas chromatography-olfactometry (CharmAnalysis™) using an RA simulator (RAS). Twenty-nine of 33 odorants detected in the RAS effluent (RAS odorants) were identified. The detected odorants were classified into 19 odor-description groups. The total odor intensity (charm value, CMV) of all coffee RAS odorants decreased approximately 68% following pH adjustment, whereas the total CMV increased 6% to 7% following ultra-high-temperature sterilization. The total CMV ratio (about 83%) of the milk coffee produced using a new blending-after-sterilization (BAS) process without pH adjustment of the coffee was greater than that (approximately 56%) prepared using a conventional blending-before-sterilization (BBS) process with pH adjustment. In BAS-processed milk coffees, the total CMV ratio (91%) with infusion (INF)-sterilized reconstituted milk (r-milk) was greater than that (83%) of plate (PLT)-sterilized r-milk. Principal component analysis of odor-description CMVs indicated that the effect of coffee pH adjustment on odor characteristics was greater than that of sterilization, that BAS and BBS samples differed, and that BAS milk coffee prepared using INF sterilization was more similar to homemade milk coffee (blending unsterilized coffee without pH adjustment with PLT-sterilized milk) than milk coffee prepared using PLT sterilization. In conclusion, the BAS process using INF sterilization is superior for manufacturing RTD milk coffee that retains odor characteristics similar to targeted homemade milk coffee. PRACTICAL APPLICATION: Ready-to-drink milk coffee beverages produced using conventional blending-before-sterilization methods do not retain their original coffee flavor following adjustment of the pH of the coffee during manufacturing. The use of newly developed blending-after-sterilization methods, by contrast, produces ready-to-drink milk coffee with an aroma more similar to that of homemade milk coffee, as demonstrated using an analytical system for characterizing food product aromas. The blending-after-sterilization process is now being used in Japan to produce ready-to-drink milk coffee beverages.
- Published
- 2018
17. Improved Durability and Sensitivity of Bitterness-Sensing Membrane for Medicines
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Kiyoshi Toko, Takeshi Shiino, Yusuke Tahara, Rui Yatabe, Xiao Wu, Hideya Onitake, Hidekazu Ikezaki, and Zhiqin Huang
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Polymers ,quinine hydrochloride ,02 engineering and technology ,lcsh:Chemical technology ,taste sensor ,bitterness sensor ,response deterioration ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,Membrane Potentials ,Contact angle ,chemistry.chemical_compound ,Hydrolysis ,Adsorption ,Adipate ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,Phosphoric acid ,chemistry.chemical_classification ,Chromatography ,Chemistry ,010401 analytical chemistry ,Plasticizer ,Polymer ,021001 nanoscience & nanotechnology ,Lipids ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Membrane ,Chemical engineering ,Taste ,0210 nano-technology - Abstract
This paper reports the improvement of a bitterness sensor based on a lipid polymer membrane consisting of phosphoric acid di-n-decyl ester (PADE) as a lipid and bis(1-butylpentyl) adipate (BBPA) and tributyl o-acetylcitrate (TBAC) as plasticizers. Although the commercialized bitterness sensor (BT0) has high sensitivity and selectivity to the bitterness of medicines, the sensor response gradually decreases to almost zero after two years at room temperature and humidity in a laboratory. To reveal the reason for the deterioration of the response, we investigated sensor membranes by measuring the membrane potential, contact angle, and adsorption amount, as well as by performing gas chromatography-mass spectrometry (GC-MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS). We found that the change in the surface charge density caused by the hydrolysis of TBAC led to the deterioration of the response. The acidic environment generated by PADE promoted TBAC hydrolysis. Finally, we succeeded in fabricating a new membrane for sensing the bitterness of medicines with higher durability and sensitivity by adjusting the proportions of the lipid and plasticizers.
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- 2017
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18. From Idea Generation to Development of Taste Sensor
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Kiyoshi Toko
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Cognitive science ,Taste ,Chemistry ,Mechanical Engineering ,Electrical and Electronic Engineering ,Ideation - Published
- 2015
19. Development of sweetness sensor with selectivity to negatively charged high-potency sweeteners
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Yusuke Tahara, Hirotaka Okazaki, Masato Yasuura, Hidekazu Ikezaki, and Kiyoshi Toko
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Taste ,Chromatography ,Electronic tongue ,Sodium ,digestive, oral, and skin physiology ,Potentiometric titration ,Metals and Alloys ,Acesulfame potassium ,food and beverages ,chemistry.chemical_element ,Umami ,Sweetness ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Membrane ,chemistry ,Materials Chemistry ,Food science ,Electrical and Electronic Engineering ,Instrumentation - Abstract
Objective taste evaluation has been much in demand in the food, beverage and pharmaceutical industries. A taste-sensing system, which is an electronic tongue with “global selectivity,” is one of the methods used for objective taste evaluation. A taste sensor electrode responds to only one of the basic tastes (saltiness, sourness, sweetness, bitterness and umami) as a change in membrane potential caused by interactions with tastants. Sweet substances are compounds with diverse chemical structures and sizes. Since the taste-sensing system is a potentiometric measurement system using a change in membrane potential, three types of sweetness sensors are required, one for sweeteners with each type of electric charge (uncharged, positively charged and negatively charged). A sweetness sensor for uncharged sweeteners has been developed. Therefore, negatively charged sweeteners, such as saccharine sodium and acesulfame potassium, were chosen as the target substances in this study. We investigated the responses of various sensor membranes using a lipid and nine kinds of plasticizers to each basic taste sample. Furthermore, not only the selectivity of the membranes but also the concentration dependence of their response to sweeteners was investigated. As a result, one of the developed sensors showed responses of over 20 mV to 5 mM saccharine sodium and 10 mM acesulfame potassium in CPA value measurement (CPA: change in membrane potential caused by adsorption). On the other hand, the sensor also showed nearly zero responses to other basic taste samples. In addition, saltiness was the only interfering taste, and the responses to target substances in relative value measurement were over 140 mV. The developed sweetness sensor had high selectivity and concentration-dependent responses. Hence, we concluded that the sensor is suitable for use as a sweetness sensor for high-potency sweeteners with a negative electric charge.
- Published
- 2014
20. [Sensors for Measuring Taste and Smell]
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Kiyoshi, Toko
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Smell ,Olfactory Cortex ,Taste ,Brain ,Humans ,Robotics ,Sensitivity and Specificity - Abstract
Gustatory and olfactory senses receive chemical substances at the biological membranes of taste and olfactory cells, respectively. The present review article describes electronic tongue (taste sensor) and electronic nose (odor sensor) developed based on biomimetic technology. A taste sensor is now commercially sold and utilized in pharmaceutical and food companies across the world. An electronic nose with high sensitivity was also commercialized in Japan. These sensors provide novel methods for analyzing chemical substances instead of using conventional tools.
- Published
- 2017
21. Development of sweetness sensor for high-potency sweeteners using lipid polymer membrane
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Kiyoshi Toko, Xiao Wu, Yusuke Tahara, Masaaki Habara, Hidekazu Ikezaki, Tomohiro Hattori, and Rui Yatabe
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chemistry.chemical_compound ,Taste ,Membrane ,Chromatography ,chemistry ,Sodium ,Potassium ,Plasticizer ,Acesulfame potassium ,Synthetic membrane ,chemistry.chemical_element ,Sweetness - Abstract
High-potency sweeteners are applied to low-calorie diets and bitterness-masking ingredients in pharmaceutical products. We have studied taste sensors with lipid polymer membranes based on potentiometric measurement system for high-potency sweeteners. However, the sensor also responds to astringency substances because of hydrophobic characteristics of the lipid polymer membrane. In this study, we developed a new taste sensor using a lipid polymer membrane for saccharin sodium and acesulfame potassium as negatively charged high-potency sweeteners. We optimized the quantities and types of lipids and plasticizers for the fabrication of the sensor with high selectivity and sensitivity. We succeeded in the fabrication of the new sensor, the output of which could be suppressed under −5 mV for astringency substances. Moreover, the sensor has a good sensitivity and selectivity for saccharin sodium and acesulfame potassium.
- Published
- 2017
22. Fabrication of taste sensor for education
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Yusuke Tahara, Xiao Wu, Kiyoshi Toko, and Hisao Kuriyaki
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Taste ,Fabrication ,Taste quality ,Trioctylmethylammonium chloride ,Chemistry ,Science teaching ,Science class ,Teflon membrane ,Nanotechnology - Abstract
In order to solve the unconcern to usefulness of learning science among high school students in Japan, we developed a simple fabricated taste sensor with sensitivity and selectivity to each taste quality, which can be applied in science class. A commercialized Teflon membrane was used as the polymer membrane holding lipids. In addition, a non-adhesive method is considered to combine the membrane and the sensor electrode using a plastic cap which is easily accessible. The taste sensor for education fabricated in this way showed a good selectivity and sensitivity. By adjusting the composition of trioctylmethylammonium chloride (TOMA) and phosphoric acid di(2-ethylhexyl) ester (PAEE) included in lipid solution, we improved the selectivity of this simple taste sensor to saltiness and sourness. To verify this taste sensor as a useful science teaching material for science class, we applied this taste sensor into a science class for university students. By comparing the results between the sensory test and the s...
- Published
- 2017
23. Examination of Amount of Astringent Substances Adsorbed Onto Lipid/Polymer Membrane Used in Taste Sensor
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Daichi Hara, Yusuke Tahara, Takuro Fukagawa, Kiyoshi Toko, and Masato Yasuura
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chemistry.chemical_classification ,Taste ,Membrane ,Adsorption ,Astringent ,chemistry ,Organic chemistry ,Polymer ,Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics - Published
- 2014
24. Development of a Sweetness Sensor for Aspartame, a Positively Charged High-Potency Sweetener
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Yusuke Tahara, Masato Yasuura, Hidekazu Ikezaki, and Kiyoshi Toko
- Subjects
Taste ,High selectivity ,Synthetic membrane ,Biosensing Techniques ,sweetness sensor ,lcsh:Chemical technology ,Biochemistry ,Article ,aspartame ,Analytical Chemistry ,Membrane Potentials ,taste sensor ,high-potency sweetener ,lipid/polymer membrane ,chemistry.chemical_compound ,Sensory tests ,Plasticizers ,Negative charge ,lcsh:TP1-1185 ,Food science ,Electrical and Electronic Engineering ,Instrumentation ,Electrodes ,Chromatography ,Aspartame ,Chemistry ,digestive, oral, and skin physiology ,food and beverages ,Esters ,Sweetness ,Lipids ,Atomic and Molecular Physics, and Optics ,Membrane ,Sweetening Agents ,Adsorption - Abstract
Taste evaluation technology has been developed by several methods, such as sensory tests, electronic tongues and a taste sensor based on lipid/polymer membranes. In particular, the taste sensor can individually quantify five basic tastes without multivariate analysis. However, it has proven difficult to develop a sweetness sensor, because sweeteners are classified into three types according to the electric charges in an aqueous solution; that is, no charge, negative charge and positive charge. Using membrane potential measurements, the taste-sensing system needs three types of sensor membrane for each electric charge type of sweetener. Since the commercially available sweetness sensor was only intended for uncharged sweeteners, a sweetness sensor for positively charged high-potency sweeteners such as aspartame was developed in this study. Using a lipid and plasticizers, we fabricated various lipid/polymer membranes for the sweetness sensor to identify the suitable components of the sensor membranes. As a result, one of the developed sensors showed responses of more than 20 mV to 10 mM aspartame and less than 5 mV to any other taste. The responses of the sensor depended on the concentration of aspartame. These results suggested that the developed sweetness sensor had high sensitivity to and high selectivity for aspartame.
- Published
- 2014
25. Taste and Other Sensors
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Chemistry ,Food science ,Electrical and Electronic Engineering - Published
- 2014
26. Taste sensor using strongly hydrophobic membranes to measure hydrophobic substances
- Author
-
Kiyoshi Toko, Yusuke Tahara, Rixin Wang, Rui Yatabe, Xiao Wu, and Ke Ji
- Subjects
Absorption (pharmacology) ,Taste ,Chromatography ,Chemistry ,Monosodium glutamate ,010401 analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Hydrophobe ,chemistry.chemical_compound ,Adsorption ,Membrane ,Pulmonary surfactant ,Sodium dodecyl sulfate ,0210 nano-technology - Abstract
A taste sensor using a lipid/polymer membrane, i.e., an electronic tongue with global selectivity, has been developed for objective evaluation of the taste of foods and beverages. Moreover, the taste sensor has been also contributing to safety of foods, e.g., the sensor membrane with strong hydrophobicity was used to detect sodium dodecyl sulfate (SDS), a negatively charged surfactant, which was generally added into the pesticide because of its strongly melting effect. An immersion process in monosodium glutamate (MSG) solution, called “MSG preconditioning” was needed to obtain the change in membrane electric potential caused by adsorption (CPA) for sensor membrane before measurement. However, what happened to sensor membrane during MSG preconditioning is unclear. In this paper, we examined the relationship between the CPA value and the period of MSG preconditioning. The amount of adsorbed SDS and MSG was measured to figure out whether the CPA value is related to the amount of adsorption. As a result, with the precondition process progressed, the CPA values showed concentration dependence on SDS concentration, and increased to a peak by preconditioning for one day then decreased to a stable state after that. The amount of adsorbed SDS depended on the SDS concentration but did not change with the increasing of preconditioning time. In conclusion, we revealed that the most suitable time of MSG preconditioning for the membrane for SDS was one day. The CPA value was affected by both the surface charge density and the amount of absorption.
- Published
- 2016
27. Development of Taste and Odor Sensing Technologies together with Sensors and Materials
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Communication ,Odor ,Computer science ,business.industry ,General Materials Science ,business ,Instrumentation - Published
- 2018
28. A Quantitative Method for Acesulfame K Using the Taste Sensor.
- Author
-
Yuanchang Liu, Xiao Wu, Yusuke Tahara, Hidekazu Ikezaki, and Kiyoshi Toko
- Subjects
SWEETNESS (Taste) ,ACESULFAME-K ,POLYMERIC membranes ,NONLINEAR regression ,QUANTITATIVE research ,TASTE - Abstract
We have developed a method to quantify the sweetness of negatively charged high-potency sweeteners coexisting with other taste substances. This kind of sweetness sensor uses lipid polymer membranes as the taste-sensing part. Two types of outputs have been defined in the measurement of the taste sensor: one is the relative value and the other is the CPA (the change in membrane potential caused by adsorption) value. The CPA value shows a good selectivity for high-potency sweeteners. On the other hand, the relative value is several times higher than the CPA value, but the relative value is influenced by salty substances. In order to obtain both high sensitivity and selectivity, we established a model for predicting the concentration of sweeteners with a nonlinear regression analysis method using the relative values of both the sweetness sensor and the saltiness sensor. The analysis results showed good correlations with the estimated concentration of acesulfame potassium coexisting with salty substances, as represented by R² = 0.99. This model can correspond well to the prediction of acesulfame K in a concentration of 0.2–0.7 mM, which is commonly used in food and beverages. The results obtained in this paper suggest that this method is useful for the evaluation of acesulfame K using the taste sensors. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
29. Electronic Tongues–A Review
- Author
-
Kiyoshi Toko and Yusuke Tahara
- Subjects
Taste ,medicine.anatomical_structure ,Human–computer interaction ,Taste receptor ,Tongue ,Computer science ,Electronic tongue ,medicine ,Nanotechnology ,Electrical and Electronic Engineering ,Instrumentation - Abstract
Sensing technologies for objective evaluation such as the discrimination and quantification of tastes have been developed since around 1990, before the discovery of taste receptors. Electronic tongues aim to discriminate and analyze foods and beverages and are well known as sensing technologies that greatly contribute to quality management. A taste sensor, i.e., an electronic tongue with global selectivity, is developed to realize a sensor that responds to taste chemical substances and can be used to quantify the type of taste focusing on the fact that humans discriminate the taste of foods and beverages on the tongue with the five basic tastes. In this paper, we focus on the taste sensor and describe its sensing principle, its difference from general electronic tongues that do not aim to quantify tastes, examples of its use, and the recent trend of research of electronic tongues.
- Published
- 2013
30. Quantification of tastes of amino acids using taste sensors
- Author
-
Yoshikazu Kobayashi, Yusuke Tahara, Masato Yasuura, Kiyoshi Toko, Hiroki Akitomi, and Hidekazu Ikezaki
- Subjects
chemistry.chemical_classification ,Taste ,Arginine ,Metals and Alloys ,food and beverages ,Sweetness ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amino acid ,Simple linear regression analysis ,stomatognathic system ,chemistry ,Materials Chemistry ,Food science ,Electrical and Electronic Engineering ,Instrumentation ,psychological phenomena and processes - Abstract
In this study, we quantified the tastes of branched-chain amino acids (BCAAs) and demonstrated the bitterness suppression effect using taste sensors that can selectively evaluate two basic taste qualities. Bitterness and sweetness sensors with a lipid/polymer membrane were used to quantity bitterness and sweetness of amino acids, respectively. Simple linear regression analysis revealed that the response values obtained from the corresponding taste sensor (bitterness, sweetness) and the scores obtained in the sensory test showed a strong correlation, demonstrating that the intensity of bitterness and sweetness of amino acids can be estimated. Moreover, a significant decrease in the response value of the bitterness sensor was observed when l -arginine ( l -Arg) was added to bitter amino acids, indicating that the bitterness suppression effect perceivable by humans can be demonstrated.
- Published
- 2013
31. Taste Sensor
- Author
-
Yoshikazu Kobayashi, Yusuke Tahara, Masaaki Habara, Kiyoshi Toko, and Hidekazu Ikezaki
- Subjects
Communication ,Taste ,Chemistry ,business.industry ,Electronic tongue ,010401 analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,business ,Selectivity ,01 natural sciences ,0104 chemical sciences - Published
- 2016
32. Evaluation of Water Quality Using Taste Sensor
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Chemistry ,Water quality ,Food science - Published
- 2016
33. 1A. Basic Principles of Taste Sensor
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Communication ,Computer science ,business.industry ,business - Published
- 2016
34. Database of Taste and Marketing
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Business ,Marketing - Published
- 2016
35. Evaluating the Reduced Hydrophobic Taste Sensor Response of Dipeptides by Theasinensin A by Using NMR and Quantum Mechanical Analyses
- Author
-
Yuji Miyata, Takashi Tanaka, Toshiro Matsui, Jian Guo, Yusuke Tahara, Kazunari Tanaka, Xiao Wu, Naoto Hirasaki, and Kiyoshi Toko
- Subjects
Models, Molecular ,Magnetic Resonance Spectroscopy ,Indoles ,Physiology ,Lipid Bilayers ,Analytical chemistry ,lcsh:Medicine ,Social Sciences ,Biosensing Techniques ,Spectrum analysis techniques ,01 natural sciences ,Physical Chemistry ,Catechin ,Diffusion ,Heterocyclic Compounds ,Medicine and Health Sciences ,Psychology ,lcsh:Science ,Membrane potential ,Multidisciplinary ,Chemistry ,Organic Compounds ,Physics ,Absorption Spectroscopy ,04 agricultural and veterinary sciences ,Nuclear magnetic resonance spectroscopy ,Dipeptides ,040401 food science ,Sensory Systems ,Partition coefficient ,Solutions ,Electrophysiology ,Membrane ,Taste ,Physical Sciences ,Thermodynamics ,Sensory Perception ,Protons ,Hydrophobic and Hydrophilic Interactions ,Protein Binding ,Research Article ,Surface Chemistry ,Absorption spectroscopy ,Membrane Potential ,0404 agricultural biotechnology ,NMR spectroscopy ,Phenols ,Humans ,Benzopyrans ,Spectroscopy ,Nuclear Physics ,Nucleons ,Chemical shift ,010401 analytical chemistry ,lcsh:R ,Organic Chemistry ,Chemical Compounds ,Resonance ,Biology and Life Sciences ,0104 chemical sciences ,Research and analysis methods ,Artificial Membranes ,Quantum Theory ,lcsh:Q ,Neuroscience - Abstract
The current study demonstrated that theasinensin A (TSA) had a potential to form the complex with hydrophobic Trp-containing dipeptides, and to reduce their membrane potential by artificial-lipid membrane taste sensor. At a 1:3 molar ratio of the 6 Trp-containing dipeptides together with TSA, we observed a significant chemical shift of the protons of the dipeptides (Δδ) to a high magnetic field, when analyzed using 1H-nuclear-magnetic resonance (NMR) spectroscopy. The Δδ values were correlated with the hydrophobicity (log P) of the dipeptides and significant correlations were obtained (P = 0.022, R2 = 0.77); e.g., Trp-Leu with the highest log P value of 1.623 among the tested dipeptides showed the highest Δδ value of 0.105 ppm for the H7 proton of Trp-Leu, while less chemical shifts were observed in theasinensin B and epigallocatechin-3-O-gallate. Diffusion-ordered NMR spectroscopy revealed that the diffusion coefficient of 3 mM of Trp-Leu (7.6 × 10−11 m2/s) at a pulse field gradient in the range 0.05–0.3 T/m decreased in the presence of 3 mM TSA (6.6 × 10−11 m2/s), suggesting that Trp-Leu forms a complex with TSA. Quantum mechanical calculations and rotating frame nuclear Overhauser effect-NMR spectroscopy provided configuration information on the geometry of the complex that Trp-Leu formed with TSA (1:1 complex) with a ΔG energy of –8.7 kJ/mol. A sensor analysis using artificial-lipid membranes demonstrated that the changes in membrane potential of 1 mM Trp-Leu (21.8 ± 1.3 mV) and Leu-Trp (5.3 ± 0.9 mV) were significantly (P < 0.001) reduced by 1 mM TSA (Trp-Leu, 13.1 ± 2.4 mV; Leu-Trp, 3.5 ± 0.5 mV; TSA alone, 0.2 ± 0.01 mV), indicating the effective suppression of hydrophobicity of dipeptides by TSA-formed complex.
- Published
- 2016
36. Beer Analysis Using an Electronic Tongue
- Author
-
Kiyoshi Toko and Yusuke Tahara
- Subjects
Taste ,Tongue map ,Chemistry ,Electronic tongue ,food and beverages ,Gustatory system ,Food science - Abstract
A taste sensor is an electronic tongue with global selectivity, which means the characteristics to decompose a chemical substance into taste qualities and to quantify each of them. It comprises several kinds of electrodes, on which a lipid/polymer membrane is pasted, and can discriminate, identify, and quantify the taste of foods or medicines. It is now commercialized, and has been applied to many kinds of foods and medicines. The composition of the membrane is designed by considering the membrane electric charge density and the hydrophobicity on the basis of physicochemical properties of taste substances. The taste is evaluated using the linear transformation of sensor output, and it provides a “scale of taste.” The obtained taste pattern for beer is constructed from five axes of five basic taste qualities. A taste map expressed by 2 axes of bitterness and sourness is obtained for 40 brands of beer. These results enable us to discuss and compare taste characteristics of beer.
- Published
- 2016
37. Advanced Taste Sensors Based on Artificial Lipids with Global Selectivity to Basic Taste Qualities and High Correlation to Sensory Scores
- Author
-
Kiyoshi Toko, Ronggang Chen, Yoshinobu Naito, Yoshikazu Kobayashi, Masaaki Habara, and Hidekazu Ikezazki
- Subjects
Taste ,Sensory system ,Umami ,Biosensing Techniques ,Review ,lcsh:Chemical technology ,Biochemistry ,Analytical Chemistry ,global selectivity ,Correlation ,Beverages ,Humans ,lcsh:TP1-1185 ,Food science ,Electrical and Electronic Engineering ,Fat Substitutes ,Instrumentation ,artificial lipid ,high correlation to human sensory score ,Chemistry ,business.industry ,Pattern recognition ,CPA value ,Atomic and Molecular Physics, and Optics ,Multivariate Analysis ,Artificial intelligence ,Neural Networks, Computer ,taste sensor ,business - Abstract
Effective R&D and strict quality control of a broad range of foods, beverages, and pharmaceutical products require objective taste evaluation. Advanced taste sensors using artificial-lipid membranes have been developed based on concepts of global selectivity and high correlation with human sensory score. These sensors respond similarly to similar basic tastes, which they quantify with high correlations to sensory score. Using these unique properties, these sensors can quantify the basic tastes of saltiness, sourness, bitterness, umami, astringency and richness without multivariate analysis or artificial neural networks. This review describes all aspects of these taste sensors based on artificial lipid, ranging from the response principle and optimal design methods to applications in the food, beverage, and pharmaceutical markets.
- Published
- 2010
38. Sensitivity-improvement of taste sensor by change of lipid concentration in membrane
- Author
-
Shu Ezaki, Satoru Iiyama, and Kiyoshi Toko
- Subjects
Detection limit ,Membrane potential ,Taste ,Chromatography ,Chemistry ,Metals and Alloys ,Condensed Matter Physics ,Dioctyl phosphate ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Dilution ,chemistry.chemical_compound ,Adsorption ,Membrane ,Materials Chemistry ,Ammonium chloride ,Electrical and Electronic Engineering ,Instrumentation - Abstract
Taste sensor responds to different taste qualities by unique patterns of output signals. The sensor uses lipid membranes as recognition element of tastes. Food constituents affect the membrane potential of the sensor mainly with shielding effect and/or adsorption. However suitable concentration of lipid in membrane has not been studied up to now. In this paper, we changed the concentration of lipid dioctyl phosphate (C) and trioctylmethyl ammonium chloride (T) in membranes, and investigated the response of the sensor to taste substances. Dilution of lipid improved the detection limit of the sensor to adsorptive taste substances, whereas the detection limit to non-adsorptive taste substances did not remarkably changed.
- Published
- 2009
39. Development of Bitter Taste Sensor Using Ionic-Liquid/Polymer Membranes
- Author
-
Jinichi Toida, Nobuyuki Akutagawa, Hidekazu Ikezaki, Yoshihiko Amano, Yukihiko Arikawa, and Kiyoshi Toko
- Subjects
Taste ,Mechanical Engineering ,Denatonium ,Synthetic membrane ,Chloride ,Polyvinyl chloride ,chemistry.chemical_compound ,Membrane ,chemistry ,Hexafluorophosphate ,Ionic liquid ,medicine ,Organic chemistry ,Electrical and Electronic Engineering ,medicine.drug - Abstract
A taste sensor is composed of several kinds of lipid/polymer membranes as transducers which convert taste information to electric signal. Thus, the role of membranes is very important to detect various taste components. In this paper, we developed novel membranes which specifically respond to quinine that is typical bitter substances. These membranes were composed of hydrophobic ionic liquid such as N, N, N-trimethyl-N-propylammonium bis(trifluoromethansulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butylpyridinium hexafluorophosphate, a plasticizer, 2-nitrophenyl octyl ether and a polymer, polyvinyl chloride. In addition to quinine, they also showed response to both several kinds of alkaloids such as caffeine and strychnine, and non-alkaloid such as phenylthiocarbamide. The order of these responses was equal to that of the tongue glossopharyngeal nerve of flog. Furthermore, there were the other alkaloids which response to these membranes. Especially in these alkaloids, they showed high response to denatonium benzoate and berberin chloride which have a strong bitter taste.
- Published
- 2009
40. Analysis of a Lipid/Polymer Membrane for Bitterness Sensing with a Preconditioning Process
- Author
-
Hidekazu Ikezaki, Yusuke Tahara, Junpei Noda, Rui Yatabe, Yoshinobu Naito, and Kiyoshi Toko
- Subjects
Polymers ,Static Electricity ,Synthetic membrane ,Analytical chemistry ,Spectrometry, Mass, Secondary Ion ,GCIB-TOF-SIMS ,lcsh:Chemical technology ,Biochemistry ,Article ,Analytical Chemistry ,Contact angle ,lipid ,Sodium Glutamate ,Spectroscopy, Fourier Transform Infrared ,Zeta potential ,XPS ,surface ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Fourier transform infrared spectroscopy ,Amines ,Aftertaste ,Lipid bilayer ,Instrumentation ,Chemistry ,Photoelectron Spectroscopy ,Water ,Membranes, Artificial ,Lipids ,Atomic and Molecular Physics, and Optics ,Secondary ion mass spectrometry ,Membrane ,Chemical engineering ,FTIR ,Taste ,taste sensor - Abstract
It is possible to evaluate the taste of foods or medicines using a taste sensor. The taste sensor converts information on taste into an electrical signal using several lipid/polymer membranes. A lipid/polymer membrane for bitterness sensing can evaluate aftertaste after immersion in monosodium glutamate (MSG), which is called "preconditioning". However, we have not yet analyzed the change in the surface structure of the membrane as a result of preconditioning. Thus, we analyzed the change in the surface by performing contact angle and surface zeta potential measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photon spectroscopy (XPS) and gas cluster ion beam time-of-flight secondary ion mass spectrometry (GCIB-TOF-SIMS). After preconditioning, the concentrations of MSG and tetradodecylammonium bromide (TDAB), contained in the lipid membrane were found to be higher in the surface region than in the bulk region. The effect of preconditioning was revealed by the above analysis methods.
- Published
- 2015
41. Development of Taste Sensor
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Communication ,Chemistry ,business.industry ,business - Published
- 2006
42. Study of the relationship between taste sensor response and the amount of epigallocatechin gallate adsorbed onto a lipid-polymer membrane
- Author
-
Yusuke Tahara, Kiyoshi Toko, and Yuhei Harada
- Subjects
Taste ,epigallocatechin gallate ,Polymers ,lipid-polymer membrane ,Biosensing Techniques ,Epigallocatechin gallate ,lcsh:Chemical technology ,Biochemistry ,complex mixtures ,Catechin ,Article ,Analytical Chemistry ,chemistry.chemical_compound ,Adsorption ,Tannic acid ,Humans ,lcsh:TP1-1185 ,heterocyclic compounds ,Electrical and Electronic Engineering ,Aftertaste ,Instrumentation ,Membrane potential ,Chromatography ,food and beverages ,Membranes, Artificial ,CPA value ,Lipids ,Atomic and Molecular Physics, and Optics ,astringent substance ,Membrane ,chemistry ,cardiovascular system ,sense organs ,taste sensor - Abstract
A taste sensor using lipid-polymer membranes has been developed to evaluate the taste of foods, beverages and medicines. The response of the taste sensor, measured as a change in the membrane potential caused by adsorption (CPA), corresponds to the aftertaste felt by humans. The relationships between the CPA value and the amount of adsorbed taste substances, quinine and iso-α acid (bitterness), and tannic acid (astringency), have been studied so far. However, that of epigallocatechin gallate (EGCg) has not been clarified, although EGCg is abundantly present in green tea as one of its astringent substances. This study aimed at clarifying the response of the taste sensor to EGCg and its relationship with the amount of EGCg adsorbed onto lipid-polymer membranes. The lipid concentration dependence of the CPA value was similar to that of the amount of adsorbed EGCg, indicating a high correlation between the CPA value and the amount of adsorbed EGCg. The CPA value increased with increasing amount of adsorbed EGCg, however, the CPA value showed a tendency of leveling off when the amount of adsorbed EGCg further increased.
- Published
- 2014
43. Kansei Biosensor and IT Society
- Author
-
Kiyoshi Toko
- Subjects
Kansei ,Electric signal ,Taste ,stomatognathic system ,Chemistry ,Mechanical Engineering ,food and beverages ,Sensory system ,Food science ,Electrical and Electronic Engineering ,Sweetness ,Biosensor - Abstract
A taste sensor with global selectivity is composed of several kinds of lipid/polymer membranes for transforming information of taste substances into electric signal. The sensor output shows different patterns for chemical substances which have different taste qualities such as saltiness and sourness. Taste interactions such as suppression effect, which occurs between bitterness and sweetness, can be detected and quantified using the taste sensor. The taste and also smell of foodstuffs such as beer, coffee, mineral water, soup and milk can be discussed quantitatively. The taste sensor provides the objective scale for the human sensory expression. Multi-modal communication becomes possible using a taste/smell recognition microchip, which produces virtual taste. We are now standing at the beginning of a new age of communication using digitized taste.
- Published
- 2004
44. Biochemical Sensors : Mimicking Gustatory and Olfactory Senses
- Author
-
Kiyoshi Toko and Kiyoshi Toko
- Subjects
- Chemical senses, Taste, Taste--Molecular aspects, Biochemical engineering, Olfactory receptors, Olfactory sensors
- Abstract
This book is the first to comprehensively treat sensors for gustatory and olfactory senses. It will be highly useful to students and researchers in a wide variety of scientific fields and also to those in the fields of foods, perfumes, medicines and robotics as the sensor applications.
- Published
- 2013
45. Peculiar change in membrane potential of taste sensor caused by umami substances
- Author
-
Kiyoshi Toko, Hidehiko Kuga, Kenshi Hayashi, Satoru Iiyama, and Shu Ezaki
- Subjects
Membrane potential ,Taste ,Monosodium glutamate ,Metals and Alloys ,Umami ,Condensed Matter Physics ,Phosphate ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Membrane ,chemistry ,Biochemistry ,Materials Chemistry ,Electrical and Electronic Engineering ,Lipid bilayer ,Instrumentation - Abstract
Monosodium glutamate (MSG) induces a favorable taste, termed umami. The action of MSG on lipid membranes of a taste sensor was investigated. In general, food constituents monotonously increase the electric potential of the negatively charged membranes. Contrary to this, MSG decreases the potential at lower concentration and increases it at higher concentration, thus the effect of MSG on lipid membrane is biphasic. On the decrease of the membrane potential, a model was proposed in which the dissociated carboxyl group of MSG accelerates the dissociation of phosphate group of the membrane lipid.
- Published
- 2003
46. Discrimination of pungent-tasting substances using surface-polarity controlled sensor with indirect in situ modification
- Author
-
Myung Jong Ju, Kosuke Hayama, Kiyoshi Toko, and Kenshi Hayashi
- Subjects
Taste ,Aqueous solution ,Chromatography ,Chemistry ,Metals and Alloys ,Electrolyte ,Condensed Matter Physics ,Electrochemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Dielectric spectroscopy ,Adsorption ,Electrode ,Materials Chemistry ,Electrical and Electronic Engineering ,Instrumentation ,Electrode potential - Abstract
Taste qualities were studied using a method for detecting the change in interactions between an electrode surface and taste substances in aqueous solution. The present method to detect chemicals was categorized into impedance spectroscopy in electrochemistry. Taste substances affect the electrochemical impedance by adsorption to the electrode surface. Dependences of the impedance on the electrode potential showed different patterns for five basic taste substances with different taste qualities. Furthermore, the response profiles obtained for capsaicin, piperine and allyl isothiocyanate, which are natural pungent-taste substances and have strong hydrophobic groups, were discriminated from those for bitter taste substances using a new method detecting the change of electrode impedance by addition of the mediators of chemical interactions to the taste substances. Hydrophobic substances, which were difficult to discriminate using the electrochemical method, could be discriminated by a proposed method; hence, it was possible to detect wide range of chemical substances from hydrophilic electrolytes to various hydrophobic non-electrolytes.
- Published
- 2003
47. Sensing of Taste
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Mechanical Engineering ,Food science ,Electrical and Electronic Engineering ,Psychology - Published
- 2003
48. Relationship between the Amount of Bitter Substances Adsorbed onto Lipid/Polymer Membrane and the Electric Response of Taste Sensors
- Author
-
Yusuke Tahara, Daichi Hara, Masato Yasuura, Hidekazu Ikezaki, and Kiyoshi Toko
- Subjects
Conductometry ,Inorganic chemistry ,Lipid Bilayers ,Transducers ,Synthetic membrane ,electronic tongue ,lcsh:Chemical technology ,Biochemistry ,Article ,Analytical Chemistry ,Membrane Potentials ,global selectivity ,Hydrophobic effect ,Adsorption ,Biomimetics ,Humans ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Instrumentation ,adsorption amount ,Membrane potential ,chemistry.chemical_classification ,Chemistry ,Charge density ,Polymer ,Equipment Design ,taste sensor ,CPA measurement ,Atomic and Molecular Physics, and Optics ,Equipment Failure Analysis ,Membrane ,Taste ,Electric potential ,Acids - Abstract
The bitterness of bitter substances can be measured by the change in the membrane electric potential caused by adsorption (CPA) using a taste sensor (electronic tongue). In this study, we examined the relationship between the CPA value due to an acidic bitter substance and the amount of the bitter substance adsorbed onto lipid/polymer membranes, which contain different lipid contents, used in the taste sensor. We used iso-α-acid which is an acidic bitter substance found in several foods and beverages. The amount of adsorbed iso-α-acid, which was determined by spectroscopy, showed a maximum at the lipid concentration 0.1 wt % of the membrane, and the same phenomenon was observed for the CPA value. At the higher lipid concentration, however, the amount adsorbed decreased and then remained constant, while the CPA value decreased monotonically to zero. This constant adsorption amount was observed when the membrane potential in the reference solution did not change with increasing lipid concentration. The decrease in CPA value in spite of the constant adsorption amount is caused by a decrease in the sensitivity of the membrane as the surface charge density increases. The reason why the peaks appeared in both the CPA value and adsorption amount is based on the contradictory adsorption properties of iso-α-acid. The increasing charged lipid concentration of the membrane causes an increasing electrostatic attractive interaction between iso-α-acid and the membrane, but simultaneously causes a decreasing hydrophobic interaction that results in decreasing adsorption of iso-α-acid, which also has hydrophobic properties, onto the membrane. Estimates of the amount of adsorption suggest that iso-α-acid molecules are adsorbed onto both the surface and interior of the membrane.
- Published
- 2014
- Full Text
- View/download PDF
49. [Kansei biosensors to reproduce gustatory and olfactory senses]
- Author
-
Kiyoshi Toko
- Subjects
Pharmacology ,Olfactory system ,Taste ,Communication ,Electronic nose ,business.industry ,Chemistry ,Electronic tongue ,Pharmaceutical Science ,Umami ,Biosensing Techniques ,Surface Plasmon Resonance ,Smell ,Intelligent sensor ,Odor ,Humans ,Electronics ,Aftertaste ,business - Abstract
Anyone talks about the taste using different taste scale. Since how to feel the taste is different from one to other people, we sometimes lead to inconsistency when speaking about the taste of food. The present study aims at development of electronic tongue (taste sensor) and electronic nose (odor sensor). There are two important properties about the taste sensor. One, each sensor electrode (lipid/polymer membrane) is specific to each taste. Another is that the sensor can measure the aftertaste such as richness, which is the aftertaste of umami. In the case of, e.g., bitterness electrode (BT0), it responds well to bitter taste substances such as quinine, cetirizine, hydroxyzine and bromhexine. For other taste qualities, on the other hand, it shows no response. A taste sensor is now sold by Intelligent Sensor Technology, Inc., and utilized in pharmaceutical and food companies. An electronic nose to detect lingering scent is composed of surface plasmon resonance (SPR) sensor, which is a sensing device with high sensitivity, and antigen-antibody interaction. A self-assembled monolayer was constructed on the reception surface of SPR device. The experimental result on benzaldehyde, a typical peach flavor, shows the sensor sensitivity 4 ppb, which is superior to the human sensitivity of about 350 ppb. Our developed taste sensor and electronic nose play the role of gustatory and olfactory senses, respectively.
- Published
- 2014
50. Quantification of suppression of bitterness using an electronic tongue
- Author
-
Koichi Wada, Kiyoshi Toko, Sou Takagi, and Toshimitsu Ohki
- Subjects
Taste ,Chromatography ,Quinine ,Electronic tongue ,Phospholipid ,Tryptophan ,Pharmaceutical Science ,Sensory system ,Phosphatidic acid ,Bitter taste ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,Tongue ,Taste Threshold ,medicine ,Humans ,lipids (amino acids, peptides, and proteins) ,Computer Simulation ,Electronics ,Quantitative analysis (chemistry) ,Phospholipids - Abstract
Phospholipids, such as phosphatidic acid, suppress bitter taste without affecting other taste qualities. In the present study, we detected and quantified this suppression effect with an electronic tongue whose transducer is composed of several kinds of lipid/polymer membranes with different characteristics. We measured a phospholipid cocktail and various kinds of taste substances with five basic taste qualities. The responses to quinine hydrochloride and L-tryptophan, which have a bitter taste, were reduced as the phospholipid concentration was increased, and the responses to the other taste substances were not affected by the phospholipids, as with the human sensation test. Furthermore, the change of bitter intensity caused by phospholipid was quantified by principal component analysis and the tau scale, which expresses the relationship between taste intensity and taste substance concentration. The results are compared with those of the human sensory test and discussed.
- Published
- 2001
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