300 results on '"Kiyoshi Toko"'
Search Results
2. Prediction of dynamic allostery for the transmembrane domain of the sweet taste receptor subunit, TAS1R3
- Author
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Keisuke Sanematsu, Masato Yamamoto, Yuki Nagasato, Yuko Kawabata, Yu Watanabe, Shusuke Iwata, Shingo Takai, Kiyoshi Toko, Toshiro Matsui, Naohisa Wada, and Noriatsu Shigemura
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Medicine (miscellaneous) ,General Agricultural and Biological Sciences ,General Biochemistry, Genetics and Molecular Biology - Abstract
The sweet taste receptor plays an essential role as an energy sensor by detecting carbohydrates. However, the dynamic mechanisms of receptor activation remain unclear. Here, we describe the interactions between the transmembrane domain of the G protein-coupled sweet receptor subunit, TAS1R3, and allosteric modulators. Molecular dynamics simulations reproduced species-specific sensitivity to ligands. We found that a human-specific sweetener, cyclamate, interacted with the mouse receptor as a negative allosteric modulator. Agonist-induced allostery during receptor activation was found to destabilize the intracellular part of the receptor, which potentially interfaces with the Gα subunit, through ionic lock opening. A common human variant (R757C) of the TAS1R3 exhibited a reduced response to sweet taste, in support of our predictions. Furthermore, histidine residues in the binding site acted as pH-sensitive microswitches to modulate the sensitivity to saccharin. This study provides important insights that may facilitate the prediction of dynamic activation mechanisms for other G protein-coupled receptors.
- Published
- 2023
3. Odor recognition of deteriorated mineral oils using an odor-sensing array
- Author
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Yuanchang Liu, Sosuke Akagawa, Rui Yatabe, Takeshi Onodera, Nobuyuki Fujiwara, Hidekazu Takeda, and Kiyoshi Toko
- Abstract
The deterioration or oxidation of the mineral oil in transformers poses the risk of short circuits. Convenient and effective methods are expected to be developed. Carbon-based sensor arrays were used in this study to identify the quality variations of mineral oil for oil-filled transformers by odors. The sensitive layers of the odor-sensing system consisted of different types of GC stationary phase materials and carbon black (CB) mixtures. We made a targeted selection of GC materials by utilizing the polarities to make a sensor array based on the distinct components of mineral oil such as alkanes and xylenes by gas chromatography mass spectrometry (GC/MS) analysis. The response characteristics of the sensitive layers were used to recognize the mineral oil odors by machine learning. With laboratory air as the carrier gas, the system could distinguish mineral oil that has been in use for over 20 years from new mineral oil with an accuracy of about 93.8%. The identification accuracy achieved was about 60% for three different concentrations of unused mineral oil and the oxidized mineral oil created by the transformer’s leakage. When detecting the oxidized mineral oil with a concentration of more than 50%, the accuracy rate reached more than 80%. The odor-sensing system in this study will help inspect mineral oils in the transformer and make leakage judgments in a short time.
- Published
- 2022
4. Odor Sensor System Using Chemosensitive Resistor Array and Machine Learning
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Akio Oki, Masaya Nakatani, Rui Yatabe, Yosuke Hanai, Atsushi Shunori, Bartosz Wyszynski, Hiroaki Oka, Kiyoshi Toko, Atsuo Nakao, and Takashi Washio
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Sensor system ,Materials science ,business.industry ,010401 analytical chemistry ,Channel data ,Chip ,Machine learning ,computer.software_genre ,01 natural sciences ,Computer Science::Other ,0104 chemical sciences ,law.invention ,Software ,Odor ,Electrical resistance and conductance ,law ,Artificial intelligence ,Electrical and Electronic Engineering ,Resistor ,business ,Instrumentation ,computer - Abstract
In this study, we developed an odor sensor system using chemosensitive resistors, which outputted multichannel data. Mixtures of gas chromatography stationary materials (GC materials) and carbon black were used as the chemosensitive resistors. The interaction between the chemosensitive resistors and gas species shifted the electrical resistance of the resistors. Sixteen different chemosensitive resistors were fabricated on an odor sensor chip. In addition, a compact measurement instrument was fabricated. Sixteen channel data were obtained from the measurements of gas species using the instrument. The data were analyzed using machine learning algorithms available on Weka software. As a result, the sensor system successfully identified alcoholic beverages. Finally, we demonstrated the classification of restroom odor in a field test. The classification was successful with an accuracy of 97.9%.
- Published
- 2021
5. Visualization of Flavor of Sake Using Taste Sensor and Gas Chromatography-Mass Spectrometry
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Keiichi Mitani, Yoichiro Kanno, Shiho Shirota, Miyo Hirata, Takeshi Onodera, and Kiyoshi Toko
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Taste ,Chromatography ,Chemistry ,Mechanical Engineering ,Electrical and Electronic Engineering ,Gas chromatography–mass spectrometry ,Flavor ,Visualization - Published
- 2020
6. 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
7. 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
8. 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.
- Published
- 2022
9. Molecular Structure Underlying the Allosteric Mechanism of Caffeine Detection in Taste Sensor
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Hengwei Xu, Zeyu Zhao, Shunsuke Kimura, Takeshi Onodera, and Kiyoshi Toko
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lipid/polymer membrane ,allosteric mechanism ,caffeine detection ,taste sensor ,Physical and Theoretical Chemistry ,surface modification ,Analytical Chemistry - Abstract
The use of taste sensors with lipid/polymer membranes is one of the methods to evaluate taste. As previously reported, taste sensors can detect non-charged substances such as caffeine by modifying the lipid/polymer membranes with hydroxybenzoic acids (HBAs). The mechanism of caffeine detection by taste sensors was identified to be an allosteric one. Generally, the allosteric mechanism, defined as “regulation at distant sites”, is used to describe the regulation process for proteins. In this study, to improve the sensitivity of taste sensors to caffeine and its analogs using the allosteric mechanism, we used various modifiers of lipid/polymer membranes, and we detected caffeine using taste sensors with the modified membranes. The detection of the caffeine analogs theophylline and theobromine was also analyzed. The results of caffeine detection clarified that the molecular structure underlying the allosteric mechanism capable of effective caffeine detection involves both the carboxyl and hydroxyl groups, where the hydroxyl group can form intermolecular H bonds with caffeine. Furthermore, the taste sensors with a modifier, which has the molecular structure underlying the allosteric mechanism, showed high sensitivity to caffeine and caffeine analogs. The use of an allosteric mechanism may help improve the sensitivity of taste sensors to other non-charged pharmaceutical substances, such as dexamethasone and prednisolone, in the future.
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- 2023
10. Taste sensor with multiarray lipid/polymer membranes
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Xiao Wu and Kiyoshi Toko
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Spectroscopy ,Analytical Chemistry - Published
- 2023
11. 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
12. Development of artificial olfactory system
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Kiyoshi Toko
- Subjects
Olfactory system ,Biology ,Neuroscience - Published
- 2019
13. Objective and Subjective Evaluation of Flavor caused by Filter for Drink Extraction
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Yusuke Tahara, Kato Kazufumi, Obi Rumina, Rui Yatabe, Zhang Shiyu, Kiyoshi Toko, and Okamura Chie
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Computer science ,business.industry ,Filter (video) ,Mechanical Engineering ,Extraction (chemistry) ,Computer vision ,Artificial intelligence ,Electrical and Electronic Engineering ,business ,Flavor - Published
- 2019
14. Potentiometric electronic tongue using lipid/polymer membrane
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Kiyoshi Toko, Hidekazu Ikezaki, Yusuke Tahara, and Masaaki Habara
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chemistry.chemical_classification ,Membrane ,Chemistry ,Electronic tongue ,Inorganic chemistry ,Potentiometric titration ,Polymer - Published
- 2021
15. Visualization of Changes in Taste of Food during Chewing Process
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Kiyoshi Toko
- Subjects
General Materials Science ,Instrumentation - Published
- 2022
16. Detection of Catecholamine Metabolite in Urine Using Surface Plasmon Resonance Sensor
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Hideto Sonoda, Toshiro Matsui, Takuya Eda, Takeshi Onodera, and Kiyoshi Toko
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Chromatography ,Surface plasmon resonance sensor ,Chemistry ,Mechanical Engineering ,Catecholamine metabolite ,Urine ,Electrical and Electronic Engineering - Published
- 2019
17. Field-effect transistor array modified by a stationary phase to generate informative signal patterns for machine learning-assisted recognition of gas-phase chemicals
- Author
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Kiyoshi Toko, Akira Matsumoto, Akio Oki, Toshihiro Yoshizumi, Takashi Washio, Hiroaki Oka, Rui Yatabe, Yuji Miyahara, and Tatsuro Goda
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Materials science ,Process Chemistry and Technology ,Transistor ,Biomedical Engineering ,Energy Engineering and Power Technology ,Signal ,Industrial and Manufacturing Engineering ,law.invention ,Gas phase ,Chemistry (miscellaneous) ,law ,Stationary phase ,Materials Chemistry ,Electronic engineering ,Chemical Engineering (miscellaneous) ,Field-effect transistor ,Computational analysis ,Gas chromatography - Abstract
We propose an artificial intelligence-based chemical-sensing system integrating a porous gate field-effect transistor (PGFET) array modified by gas chromatography stationary phase materials and machine-learning techniques. The chemically sensitive PGFET array generates cross-reactive signals for computational analysis and shows potential for applications to compact intelligent sensing devices, including mobile electronic noses.
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- 2019
18. 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
19. Identification of the Principle of Taste Sensors to Detect Non-Charged Bitter Substances by 1H-NMR Measurement
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Misaki Ishida, Haruna Ide, Keishiro Arima, Zeyu Zhao, Toshiro Matsui, and Kiyoshi Toko
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hydroxybenzoic acid ,hydrogen bond ,allostery ,taste sensor ,Electrical and Electronic Engineering ,e-tongues ,Biochemistry ,Instrumentation ,NMR ,Atomic and Molecular Physics, and Optics ,caffeine ,Analytical Chemistry - 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 1H-nuclear magnetic resonance spectroscopy (NMR). By the 1H NMR detection, we confirmed that both the substances interact with each other. Furthermore, the nuclear Overhauser effect (NOE) of intermolecular spatial conformation in solution was measured, by which 2,6-dihydroxybenzoic acid (2,6-DHBA) preferably interacted with caffeine via the H-bonding and stacking configuration between aromatic rings. Identifying the binding form of 2,6-DHBA to caffeine was estimated to predict how the two substances interact.
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- 2022
20. Effects of Manufacturing Processing Conditions on Retronasal-Aroma Odorants from a Milk Coffee Drink
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Yuta Hirano, Michio Ikeda, Yasunori Sugawara, Hisakatsu Iwabuchi, Kazuhiro Miyaji, Yuriko Imayoshi, Takeshi Onodera, Masayuki Akiyama, and Kiyoshi Toko
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Coffee Flavor ,biology ,Chemistry ,010401 analytical chemistry ,Flavour ,food and beverages ,04 agricultural and veterinary sciences ,Sterilization (microbiology) ,biology.organism_classification ,040401 food science ,01 natural sciences ,0104 chemical sciences ,0404 agricultural biotechnology ,Milk products ,Odor ,Food science ,Aroma ,Food Science - 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
21. 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.
- Published
- 2019
22. Highly Selective Rational Design of Peptide-Based Surface Plasmon Resonance Sensor for Direct Determination of 2,4,6-trinitrotoluene (TNT) Explosive
- Author
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Mina Okochi, Jin Wang, Masayoshi Tanaka, Rui Yatabe, Kiyoshi Toko, Takeshi Onodera, Masaki Muto, and Yusuke Tahara
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chemistry.chemical_classification ,Chemistry ,010401 analytical chemistry ,Metals and Alloys ,Rational design ,Peptide ,02 engineering and technology ,Complementarity determining region ,musculoskeletal system ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Materials Chemistry ,Trinitrotoluene ,Amine gas treating ,Electrical and Electronic Engineering ,Surface plasmon resonance ,0210 nano-technology ,Instrumentation ,Peptide sequence ,Conjugate - Abstract
In this study, 2,4,6-trinitrotoluene (TNT) binding peptide was synthesized and screened for TNT specific detection using surface plasmon resonance (SPR) sensor. The TNT binding peptide was rational design and synthesized through amino acid sequence from complementarity determining region (CDR) in the anti-TNT monoclonal antibody, which was produced from hybridoma cell using TNP-KLH conjugate as antigen. Three TNT binding peptide sequences were obtained from the heavy chain of CDR1 named TNTHCDR1, TNTHCDR2 from CDR2 and TNTHCDR3 from CDR3 of anti-TNT antibody. Screening process of three candidate peptides were carried out by using the SPR sensor with direct determination, which the peptide was directly immobilized on the sensor chip CM7 surface through amine coupling reaction. The results demonstrated that peptide TNTHCDR3 was determined as TNT binding peptide and no non-specific binding was observed. The selectivity of TNT binding peptide TNTHCDR3 was also testified by six kinds of TNT analogues. The results indicated the specific binding between TNT and peptide TNTHCDR3.
- Published
- 2018
23. Effects of Processing Conditions During Manufacture on Retronasal-Aroma Compounds from a Milk Coffee Drink
- Author
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Kono Masaya, Kazuhiro Miyazi, Masayuki Akiyama, Yuta Hirano, Takeshi Onodera, Michio Ikeda, Yuriko Imayoshi, Hisakatsu Iwabuchi, and Kiyoshi Toko
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0106 biological sciences ,Coffee Flavor ,biology ,Chemistry ,Manufacturing process ,education ,Flavour ,Sterilized milk ,food and beverages ,04 agricultural and veterinary sciences ,Sterilization (microbiology) ,biology.organism_classification ,040401 food science ,01 natural sciences ,0404 agricultural biotechnology ,Milk products ,010608 biotechnology ,Food science ,Effluent ,Aroma ,Food Science - Abstract
To develop a ready‐to‐drink (RTD) milk coffee retaining the original coffee flavor, the effects of processing conditions during manufacture on retronasal‐arma (RA) compounds from the milk coffee were investigated by gas chromatography‐mass spectrometry using an RA simulator (RAS). Thirteen of 46 detected compounds in the RAS effluent (RAS compounds) decreased significantly following pH adjustment of coffee (from pH 5.1 to 6.8) and 5 compounds increased. RAS compounds from coffee tended to decrease through the pH adjustment and subsequent sterilization. Significantly higher amounts of 13 RAS compounds were released from the milk coffee produced using a blending‐after‐sterilization (BAS) process without the pH adjustment than from that using a blending‐before‐sterilization (BBS) process with the pH adjustment. In BAS‐processed milk coffee, significantly lower amounts of 8 high‐volatility compounds and 1H‐pyrrole were released from coffee containing infusion‐sterilized (INF) milk than from coffee containing plate‐sterilized (PLT) milk, whereas 3 low‐volatility compounds were released significantly more from coffee using PLT milk. Principal component analysis revealed that the effect of the manufacturing process (BAS, BBS, or homemade (blending unsterilized coffee without pH adjustment with sterilized milk)) on milk coffee volatiles was larger than that of the sterilization method (INF or PLT) for milk, and that the sterilization method could result in different RAS volatile characteristics in BAS and homemade processes. In conclusion, a BAS process was found to be superior to a BBS process for the manufacture of an RTD milk coffee that retains volatile characteristics similar to that of a homemade milk coffee. Ready‐to‐drink (RTD) milk coffee manufactured using the conventional blending‐before‐sterilization process does not retain its original coffee flavor due to pH adjustment of the coffee during the process. The new blending‐after‐sterilization (BAS) process enabled the production of RTD milk coffee whose volatiles are closer to that of homemade milk coffee, as demonstrated by the results of RAS‐GC‐MS analysis. The BAS process has already been applied to the manufacture of RTD milk coffees in Japan.
- Published
- 2018
24. Effect of Grain Size on the Response to Oxygen Gas of CuFeTe2 Ceramics
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Yuta Tokunaga, Masatoshi Kozaki, Kiyoshi Toko, and Hisao Kuriyaki
- Subjects
010302 applied physics ,Materials science ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Grain size ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Ceramic ,Electrical and Electronic Engineering ,Oxygen gas ,0210 nano-technology - Published
- 2017
25. Quantitative prediction of bitterness masking effect of high-potency sweeteners using taste sensor
- Author
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Yusuke Tahara, Tamami Haraguchi, Hidekazu Ikezaki, Miyako Yoshida, Rui Yatabe, Xiao Wu, Hideya Onitake, Takahiro Uchida, and Kiyoshi Toko
- Subjects
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.
- Published
- 2016
26. Development of a Sensor with a Lipid/Polymer Membrane Comprising Na
- Author
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Futa, Nakatani, Tomofumi, Ienaga, Xiao, Wu, Yusuke, Tahara, Hidekazu, Ikezaki, Hiroyuki, Sano, Yuki, Muto, Yuya, Kaneda, and Kiyoshi, Toko
- Subjects
ionophore ,saltiness sensor ,lipid/polymer membrane ,saltiness enhancement effect ,taste sensor ,Article - 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
27. Surfactant cleaning of lipid polymer membranes of bitterness sensor
- Author
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Hidekazu Ikezaki, Yapeng Yuan, Xiao Wu, Rui Yatabe, Kiyoshi Toko, and Yusuke Tahara
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Cleaning agent ,chemistry.chemical_classification ,High concentration ,Chemistry ,Synthetic membrane ,food and beverages ,Polymer ,Linear alkylbenzene sulfonate ,Membrane ,stomatognathic system ,Pulmonary surfactant ,Chemical engineering ,Selectivity ,psychological phenomena and processes - Abstract
The bitterness sensor with negatively charged lipid polymer membrane has been reported to perform high sensitivity and selectivity to bitterness of medicines. However, the conventional cleaning solution cannot completely remove residual substances after measuring high concentration bitter samples. Surfactant is an important cleaning agent used for membrane materials. This paper reported the effects of four kinds of surfactants in cleaning the lipid polymer membrane of the bitterness sensor. Among these surfactants, anionic surfactant linear alkylbenzene sulfonate (LAS) showed no detectable impact on membrane integrity and a good cleaning effect for the bitterness sensor.
- Published
- 2019
28. Multichannel Odor Sensor System using Chemosensitive Resistors and Machine Learning
- Author
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Takashi Washio, Yosuke Hanai, Atsuo Nakao, Atsushi Shunori, Masaya Nakatani, Bartosz Wyszynski, Kiyoshi Toko, Rui Yatabe, Hiroaki Oka, and Akio Oki
- Subjects
Sensor system ,Computer science ,business.industry ,Machine learning ,computer.software_genre ,Chip ,Chemical sensor ,law.invention ,Sensor array ,Odor ,Artificial olfaction ,law ,Artificial intelligence ,Resistor ,business ,computer - Abstract
In this study, we have fabricated multichannel odor sensor using chemosensitive resistors. The chemosensitive resistors were made from complex of carbon black and gas chromatography stationary materials (GC materials). The electrical resistance of the chemosensitive resistor changed by sensing gas species. We have fabricated an odor sensor chip, which had 16 types of chemosensitive resistors. In addition, we developed a measurement instrument with compact size. The odor sensor chip was embedded in the instrument to construct an odor sensor system. The sensor system outputted the data of 16 channels if sensing gas species. The data have been analyzed using machine learning algorithms that were available on software Weka. As a result, it was successful to identify alcohol beverages by sensing their odor using the sensor system.
- Published
- 2019
29. ISOEN 2019 Front Matter
- Author
-
Kiyoshi Toko
- Published
- 2019
30. Bitterness compounds in coffee brew measured by analytical instruments and taste sensing system
- Author
-
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
- Subjects
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
31. Detection of Capsaicinoids in Capsicum Fruit Using Surface Plasmon Resonance Immunosensor
- Author
-
Shengxi Tian, Takeshi Onodera, Rui Yatabe, and Kiyoshi Toko
- Subjects
business.industry ,Chemistry ,Mechanical Engineering ,010401 analytical chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,Surface plasmon resonance ,010402 general chemistry ,business ,01 natural sciences ,0104 chemical sciences - Published
- 2016
32. Taste and Odor Sensors
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Odor ,Chemistry ,Food science - Published
- 2016
33. A bioinspired peptide matrix for the detection of 2,4,6-trinitrotoluene (TNT)
- Author
-
Kiyoshi Toko, Takumi Komikawa, Kevin Critchley, Mina Okochi, Takeshi Onodera, Kentaro Yanai, Benjamin R. G. Johnson, Masayoshi Tanaka, and Stephen D. Evans
- Subjects
Surface Properties ,Aptamer ,Biomedical Engineering ,Biophysics ,Peptide ,02 engineering and technology ,Binding, Competitive ,01 natural sciences ,Matrix (chemical analysis) ,Molecular recognition ,Explosive Agents ,Limit of Detection ,Electrochemistry ,Explosive detection ,Molecule ,Amino Acid Sequence ,Cysteine ,Disulfides ,Surface plasmon resonance ,Solid-Phase Synthesis Techniques ,chemistry.chemical_classification ,Molecular Structure ,Chemistry ,010401 analytical chemistry ,Antibodies, Monoclonal ,Equipment Design ,General Medicine ,Surface Plasmon Resonance ,021001 nanoscience & nanotechnology ,Combinatorial chemistry ,0104 chemical sciences ,Thermodynamics ,ATP-Binding Cassette Transporters ,Paratope ,Peptides ,0210 nano-technology ,Aptamers, Peptide ,Trinitrotoluene ,Biotechnology - Abstract
A novel peptide-based three-dimensional probe called “peptide matrix,” inspired by the antibody paratope region, was fabricated on a surface plasmon resonance (SPR) sensor chip to enhance the sensitivity of detecting the explosive 2,4,6-trinitrotoluene (TNT). Although peptide aptamer is an attractive candidate for a molecular recognition probe because of its ease of synthesis and chemical stability, it still has difficulty in applying to highly sensitive (i.e. parts-per-billion (ppb) or sub-ppb level) detections. Thus, we developed the concept of peptide matrix structure, which is constructed by consecutive disulfide bond formation between a large number of peptide fragments. This robust three-dimensional structure displays multiple binding sites which can efficiently associate with each TNT molecule. The peptide matrix lowered the dissociation constant (KD) by two orders of magnitude compared to the linear peptide aptamer, estimating KD as 10.1 nM, which is the lowest concentration reported by using peptide-based TNT probe. Furthermore, the concentration limit of detection of peptide matrix modified SPR sensor was 0.62 ppb, and hence comparable to single-chain variable fragment (scFv)-based TNT sensors. To our knowledge, this is the first report demonstrating peptide matrix fabrication and its application for small explosive molecule detection. This peptide matrix-based approach, which has the advantage of simple synthesis and high sensitivity, will be applicable to many other small-molecule label-free detections.
- Published
- 2020
34. Quantification of bitterness of coffee in the presence of high-potency sweeteners using taste sensors
- Author
-
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
- Subjects
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
35. Development of a Sensor with a Lipid/Polymer Membrane Comprising Na+ Ionophores to Evaluate the Saltiness Enhancement Effect
- Author
-
Hiroyuki Sano, Kiyoshi Toko, Xiao Wu, Yusuke Tahara, Hidekazu Ikezaki, Futa Nakatani, Tomofumi Ienaga, Yuki Muto, and Yuya Kaneda
- Subjects
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
36. [Research of the Cancer-Odor]
- Author
-
Hideto, Sonoda, Eiji, Oki, Mitsuru, Tanaka, Toshiro, Matsui, Takeshi, Onodera, Kiyoshi, Toko, Yuji, Satoh, and Yoshihiko, Maehara
- Subjects
Smell ,Neoplasms ,Odorants ,Animals ,Humans ,Early Detection of Cancer - Abstract
Early detection and resection of cancer is the most effective in the treatment of solid cancer. Development of a new cancer detection method is expected to become a breakthrough to solve various problems for early detection. It has been reported that there is the specific odors of cancer by using bio olfaction such as dogs, and it has been recognized that there is the odors of cancer. Cancer cells acquire malignant traits as a result of metabolic changes originating from genetic mutation. The cancer specific odorous substances may be considered to be the end products of their metabolic changes. Omics researches such as genomics, proteomics, and metabolomics have been extensively performed to comprehensively analyze changes in DNA, RNA, protein, metabolism and its products specific to cancer for the purpose of developing a new cancer detection marker. It is thought that the research on the odor of cancer is also on the line of omics research. It is difficult to identify cancer-specific odorants buried in various environmental substances. However, it is expected that human will be able to acquire the technology, from the fact that they can be recognized by biological olfaction. We are continuing the research with the dream that identification of the odorous substances as a new cancer detection marker and sensor development for it will lead to the happiness of colleagues in the world.
- Published
- 2018
37. Effects of Manufacturing Processing Conditions on Retronasal-Aroma Odorants from a Milk Coffee Drink
- Author
-
Michio, Ikeda, Masayuki, Akiyama, Yuta, Hirano, Kazuhiro, Miyaji, Yasunori, Sugawara, Yuriko, Imayoshi, Hisakatsu, Iwabuchi, Takeshi, Onodera, and Kiyoshi, Toko
- Subjects
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
38. Laser-induced damage threshold test for interfacial analysis of lipid polymer membrane
- Author
-
Kiyoshi Toko, Yusuke Tahara, Masatoshi Kozaki, Satoshi Ikezawa, and Rui Yatabe
- Subjects
chemistry.chemical_classification ,Materials science ,Threshold test ,010401 analytical chemistry ,Synthetic membrane ,020206 networking & telecommunications ,02 engineering and technology ,Polymer ,Laser ,Polarization (waves) ,01 natural sciences ,0104 chemical sciences ,law.invention ,Membrane ,chemistry ,Chemical engineering ,law ,0202 electrical engineering, electronic engineering, information engineering ,Molecule ,Spectroscopy - Abstract
This paper describes a preliminary test for sum-frequency generation (SFG) spectroscopy analysis of lipid polymer membranes. The SFG technique is used to analyze surface and structural information of molecules at gas-solid, gas-liquid, liquid-solid interfaces. A specially designed SFG system, which allows to analyze orientational polarization of polymer molecules at interfaces between a lipid polymer membrane and liquid/gas/solid, is being developed in our laboratory. A laser-induced damage threshold test of lipid polymer membranes was conducted in an early stage of this work.
- Published
- 2017
39. Taste Sensor as a Science Teaching Material
- Author
-
Yusuke Tahara, Kiyoshi Toko, Xiao Wu, Hisao Kuriyaki, and Kazushi Kuwamoto
- Subjects
Engineering ,business.industry ,Mechanical Engineering ,Taste (sociology) ,media_common.quotation_subject ,Science teaching ,Electrical engineering ,Engineering ethics ,Electrical and Electronic Engineering ,business ,media_common - Published
- 2015
40. From Idea Generation to Development of Taste Sensor
- Author
-
Kiyoshi Toko
- Subjects
Cognitive science ,Taste ,Chemistry ,Mechanical Engineering ,Electrical and Electronic Engineering ,Ideation - Published
- 2015
41. Review of Development of Sweetness Sensor
- Author
-
Masato Yasuura and Kiyoshi Toko
- Subjects
World Wide Web ,Thesaurus (information retrieval) ,Engineering ,business.industry ,Mechanical Engineering ,Electrical and Electronic Engineering ,Sweetness ,business - Published
- 2015
42. Effects of Processing Conditions During Manufacture on Retronasal-Aroma Compounds from a Milk Coffee Drink
- Author
-
Michio, Ikeda, Masayuki, Akiyama, Yuta, Hirano, Kazuhiro, Miyazi, Masaya, Kono, Yuriko, Imayoshi, Hisakatsu, Iwabuchi, Takeshi, Onodera, and Kiyoshi, Toko
- Subjects
Flavoring Agents ,Volatile Organic Compounds ,Milk ,Japan ,Food Handling ,Odorants ,Animals ,Cattle ,Coffee ,Gas Chromatography-Mass Spectrometry - Abstract
To develop a ready-to-drink (RTD) milk coffee retaining the original coffee flavor, the effects of processing conditions during manufacture on retronasal-arma (RA) compounds from the milk coffee were investigated by gas chromatography-mass spectrometry using an RA simulator (RAS). Thirteen of 46 detected compounds in the RAS effluent (RAS compounds) decreased significantly following pH adjustment of coffee (from pH 5.1 to 6.8) and 5 compounds increased. RAS compounds from coffee tended to decrease through the pH adjustment and subsequent sterilization. Significantly higher amounts of 13 RAS compounds were released from the milk coffee produced using a blending-after-sterilization (BAS) process without the pH adjustment than from that using a blending-before-sterilization (BBS) process with the pH adjustment. In BAS-processed milk coffee, significantly lower amounts of 8 high-volatility compounds and 1H-pyrrole were released from coffee containing infusion-sterilized (INF) milk than from coffee containing plate-sterilized (PLT) milk, whereas 3 low-volatility compounds were released significantly more from coffee using PLT milk. Principal component analysis revealed that the effect of the manufacturing process (BAS, BBS, or homemade (blending unsterilized coffee without pH adjustment with sterilized milk)) on milk coffee volatiles was larger than that of the sterilization method (INF or PLT) for milk, and that the sterilization method could result in different RAS volatile characteristics in BAS and homemade processes. In conclusion, a BAS process was found to be superior to a BBS process for the manufacture of an RTD milk coffee that retains volatile characteristics similar to that of a homemade milk coffee.Ready-to-drink (RTD) milk coffee manufactured using the conventional blending-before-sterilization process does not retain its original coffee flavor due to pH adjustment of the coffee during the process. The new blending-after-sterilization (BAS) process enabled the production of RTD milk coffee whose volatiles are closer to that of homemade milk coffee, as demonstrated by the results of RAS-GC-MS analysis. The BAS process has already been applied to the manufacture of RTD milk coffees in Japan.
- Published
- 2017
43. [Sensors for Measuring Taste and Smell]
- Author
-
Kiyoshi, Toko
- Subjects
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
44. Development of sweetness sensor for high-potency sweeteners using lipid polymer membrane
- Author
-
Kiyoshi Toko, Xiao Wu, Yusuke Tahara, Masaaki Habara, Hidekazu Ikezaki, Tomohiro Hattori, and Rui Yatabe
- Subjects
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
45. Fabrication of taste sensor for education
- Author
-
Yusuke Tahara, Xiao Wu, Kiyoshi Toko, and Hisao Kuriyaki
- Subjects
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
46. Development of sweetness sensor with selectivity to negatively charged high-potency sweeteners
- Author
-
Yusuke Tahara, Hirotaka Okazaki, Masato Yasuura, Hidekazu Ikezaki, and Kiyoshi Toko
- Subjects
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
47. Examination of Amount of Astringent Substances Adsorbed Onto Lipid/Polymer Membrane Used in Taste Sensor
- Author
-
Daichi Hara, Yusuke Tahara, Takuro Fukagawa, Kiyoshi Toko, and Masato Yasuura
- Subjects
chemistry.chemical_classification ,Taste ,Membrane ,Adsorption ,Astringent ,chemistry ,Organic chemistry ,Polymer ,Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics - Published
- 2014
48. Coherent lateral-growth of Ge over insulating film by rapid-melting-crystallization
- Author
-
Masanobu Miyao, Masashi Kurosawa, Kiyoshi Toko, and Taizoh Sadoh
- Subjects
Coalescence (physics) ,Materials science ,Condensed matter physics ,Scanning electron microscope ,Metals and Alloys ,Surfaces and Interfaces ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,Crystallography ,Crystallinity ,law ,Transmission electron microscopy ,Lattice (order) ,Materials Chemistry ,Crystallization - Abstract
In rapid-melting-crystallization of network Ge-on-insulator (GOI), coalescence of growth-fronts inevitably occurs. To clarify crystallinity of the coalesced regions of two growth-fronts in GOI stripes, scanning electron microscopy and transmission electron microscopy analyses are performed. These analyses reveal that lattice planes of two growth-fronts coherently align without strains for short growth-distance (≤ 5 μm). The lattice planes at growth-fronts start to tilt gradually for growth-distance above 5 μm. For intermediate growth-distance (5–150 μm), slightly-tilting lattice-planes coherently align without generating any defects, where locally-distributed strains are induced in the coalesced regions. On the other hand, for long growth-distance (≥ 150 μm), grain-boundaries are generated in coalesced regions, and the locally-distributed strains are relaxed. The coherent lattice-alignment for growth-distance below 150 μm is attributed to atomic reordering in the coalesced regions, where coalescence occurs at high temperatures around the solidification point of Ge.
- Published
- 2014
49. Development of Taste Sensor as a Teaching Material Comprehending Science Subjects in High School
- Author
-
Yusuke Tahara, Masato Yasuura, Kiyoshi Toko, Kazushi Kuwamoto, Hisao Kuriyaki, and Hitoshi Arase
- Subjects
Engineering ,business.industry ,Taste (sociology) ,media_common.quotation_subject ,Mathematics education ,Electrical and Electronic Engineering ,business ,media_common - Published
- 2014
50. Taste and Other Sensors
- Author
-
Kiyoshi Toko
- Subjects
Taste ,Chemistry ,Food science ,Electrical and Electronic Engineering - Published
- 2014
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