The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Thomas Hofmann - One of the best experts on this subject based on the ideXlab platform.
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characterization of bitter and astringent off taste compounds in potato fibers
Journal of Agricultural and Food Chemistry, 2020Co-Authors: Tara Duggan, Corinna Dawid, Sebastian Baur, Thomas HofmannAbstract:Applying the Sensomics approach, a combination of acitivity guided fractionation and taste dilution analysis (TDA) followed by high-performance liquid chromatography tandem mass spectrometry (HPLC-...
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impact of oral astringent stimuli on surface charge and morphology of the protein rich pellicle at the tooth saliva interphase
Colloids and Surfaces B: Biointerfaces, 2019Co-Authors: Ralf Zimmermann, Judith Delius, Thomas Hofmann, Melanie Rehage, Jens Friedrichs, Susanne Stehl, Christian Hannig, Carsten Werner, Matthias HannigAbstract:Abstract The proteinaceous pellicle layer, which develops upon contact with saliva on the surface of teeth, is important for the formation of oral biofilms and for the protection of teeth from abrasion and chemically induced erosion. Astringent food ingredients comprising polyphenols, cationic macromolecules, and multivalent metal salts are known to interact with the pellicle. However, astringent-induced changes in the physicochemical properties of the tooth-saliva interphase are not yet completely understood. Here we provide comprehensive insights into interfacial charging, ultrastructure, thickness, and surface roughness of the pellicles formed on the model substrates silicon oxide (SiO2), Teflon® AF, and hydroxyapatite, as well as on bovine enamel before and after incubation with the astringents epigallocatechin gallate, tannic acid, iron(III) salt, lysozyme, and chitosan. Quartz crystal microbalance with dissipation monitoring demonstrated viscous behavior of untreated pellicles formed in vitro on the different materials. Electrokinetic (streaming current) measurements revealed that cationic astringents reverse the charge of native pellicles, whereas polyphenols did not change the charge under physiological pH condition. In addition, transmission electron microscopy and atomic force microscopy showed a concentration-dependent increase in average film thickness and pellicle surface roughness as induced by astringents. These multifaceted alterations of the salivary pellicle may come along with an increase in roughness perceived on the teeth, which is part of the complex sensations of oral astringency.
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label free quantitative 1h nmr spectroscopy to study low affinity ligand protein interactions in solution a contribution to the mechanism of polyphenol mediated astringency
PLOS ONE, 2017Co-Authors: Judith Delius, Oliver Frank, Thomas HofmannAbstract:Nuclear magnetic resonance (NMR) spectroscopy is well-established in assessing the binding affinity between low molecular weight ligands and proteins. However, conventional NMR-based binding assays are often limited to small proteins of high purity and may require elaborate isotopic labeling of one of the potential binding partners. As protein–polyphenol complexation is assumed to be a key event in polyphenol-mediated oral astringency, here we introduce a label-free, ligand-focused 1H NMR titration assay to estimate binding affinities and characterize soluble complex formation between proteins and low molecular weight polyphenols. The method makes use of the effects of NMR line broadening due to protein–ligand interactions and quantitation of the non-bound ligand at varying protein concentrations by quantitative 1H NMR spectroscopy (qHNMR) using electronic reference to access in vivo concentration (ERETIC 2). This technique is applied to assess the interaction kinetics of selected astringent tasting polyphenols and purified mucin, a major lubricating glycoprotein of human saliva, as well as human whole saliva. The protein affinity values (BC50) obtained are subsequently correlated with the intrinsic mouth-puckering, astringent oral sensation imparted by these compounds. The quantitative NMR method is further exploited to study the effect of carboxymethyl cellulose, a candidate “anti-astringent” protein binding antagonist, on the polyphenol–protein interaction. Consequently, the NMR approach presented here proves to be a versatile tool to study the interactions between proteins and low-affinity ligands in solution and may find promising applications in the discovery of bioactives.
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oral astringent stimuli alter the enamel pellicle s ultrastructure as revealed by electron microscopy
Journal of Dentistry, 2017Co-Authors: Melanie Rehage, Judith Delius, Thomas Hofmann, Matthias HannigAbstract:Abstract Objectives This electron microscopic study aimed at investigating effects of oral astringent stimuli on the enamel pellicle’s morphology. Methods Pellicles were formed in situ within 30 min on bovine enamel slabs, fixed to individuals’ upper jaw splints. The pellicle-coated specimens were immersed in vitro in seven diverse astringent solutions and subsequently analyzed by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, as well as transmission electron microscopy (TEM). Four biocompatible astringents, namely the polyphenol epigallocatechin gallate, the metal salt iron(III) sulfate, the basic protein lysozyme, and the aminopolysaccharide chitosan, were additionally applied in situ. After rinsing the oral cavity with these compounds, the pellicle’s ultrastructure was imaged by SEM and TEM, respectively. Untreated pellicle samples served as controls. Results Exposure to polyphenols and lysozyme induced particularly thicker and electron-denser pellicles in comparison to the control pellicle with similar characteristics in vitro and in situ. In contrast, acidic chitosan and metal salt solutions, respectively, revealed minor pellicle alterations. The incorporation of Fe and Al into the pellicles treated with the corresponding inorganic salts was verified by EDX analysis. Conclusions Astringent-induced pellicle modifications were for the first time visualized by TEM. The ultrastructural alterations of the dental pellicle may partly explain the tooth-roughening effect caused by oral astringent stimuli. Clinical significance Astringents might modify the pellicle’s protective properties against dental erosion, attrition, as well as bacterial adhesion, and by this means may influence tooth health. The findings may thus be particularly relevant for preventive dentistry.
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matrix calibrated lc ms ms quantitation and sensory evaluation of oak ellagitannins and their transformation products in red wines
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Timo D. Stark, Nadine Wollmann, Kerstin Wenker, Sofie Losch, Arne Glabasnia, Thomas HofmannAbstract:Aimed at investigating the concentrations and taste contribution of the oak-derived ellagitannins castalagin and vescalagin as well as their transformation products acutissimin A/B, epiacutissimin A/B, and β-1-O-ethylvescalagin in red wine, a highly sensitive and accurate quantification method was developed on the basis of LC-MS/MS-MRM analysis with matrix calibration. Method validation showed good recovery rates ranging from 102.4 ± 5.9% (vescalagin) to 113.7 ± 15.2% (epiacutissimin A). In oak-matured wines, castalagin was found as the predominant ellagitannin, followed by β-1-O-ethylvescalagin, whereas the flavano-C-ellagitannins (epi)acutissimin A/B were present in significantly lower amounts. In contrast to the high threshold concentration levels (600−1000 μmol/L) and the puckering astringent orosensation induced by flavan-3-ols, all of the ellagitannin derivatives were found to induce a smooth and velvety astringent oral sensation at rather low threshold concentrations ranging from 0.9 to 2.8 μmol/L....
Masahiko Yamada - One of the best experts on this subject based on the ideXlab platform.
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persimmon breeding in japan for pollination constant non astringent pcna type with marker assisted selection
Breeding Science, 2016Co-Authors: Akihiko Sato, Masahiko YamadaAbstract:Oriental persimmon (Diospyros kaki) originated in Eastern Asia, and many indigenous cultivars have been developed in China, Japan, and Korea. These cultivars are classified into four groups based on their natural astringency loss on the tree and seed formation: pollination-constant non-astringent (PCNA), pollination-variant non-astringent (PVNA), pollination-constant astringent (PCA), and pollination-variant astringent (PVA). PCNA is the most desirable type because the fruit can be eaten without any postharvest treatment; therefore, one of the goals of our persimmon breeding programs is to release superior PCNA cultivars. The PCNA genotype is recessive to the other three non-PCNA genotypes, and PCNA-type F1 offspring are obtained exclusively from crosses among PCNA genotypes. Moreover, the number of superior PCNA cross-parents have been limited. In the late 1980s, inbreeding depression became obvious, especially in terms of fruit size, tree vigor, and productivity. To mitigate the inbreeding, a backcross program using PCNA [(non-PCNA × PCNA) × PCNA] was started in 1990. This process, however, was inefficient because only 15% of the offspring were PCNA, and all offspring had to be grown to the fruiting stage. Therefore, molecular markers linked to the PCNA locus were developed for discriminating PCNA offspring. A molecular marker linked to Chinese PCNA has also been developed.
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relationships among asian persimmon cultivars astringent and non astringent types
Tree Genetics & Genomes, 2015Co-Authors: Dan E Parfitt, Keizo Yonemori, Chitose Honsho, Mitsunori Nozaka, Shinya Kanzaki, Akihiko Sato, Masahiko YamadaAbstract:A molecular marker analysis for Asian persimmon cultivar relationships and pollination status was conducted with 496 amplified fragment length polymorphism (AFLP) markers and 146 cultivars of Asian origin. Cultivars from China, Korea, and Japan were evaluated for marker composition and pollination status, which strongly influences fruit characteristics. Separation of Chinese, Korean, and Japanese cultivar groups and pollination type by neighbor-joining clustering, multidimensional scaling, and STRUCTURE was only weakly supported and not genetically significant. Significant differences for cultivar origin and pollination status were found for analysis of molecular variance (AMOVA), but most of the variation was among cultivars, not classification groups. All of the cultivar groups were genetically similar at the molecular level with most polymorphism due to individual cultivar differences.
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development of molecular markers linked to the allele associated with the non astringent trait of the chinese persimmon diospyros kaki thunb
Journal of The Japanese Society for Horticultural Science, 2011Co-Authors: Ayako Ikegami, Shinya Kanzaki, Akihiko Sato, Masahiko Yamada, Sai Eguchi, Akira Kitajima, Takashi Akagi, Keizo YonemoriAbstract:Persimmon cultivars are classified into four types depending on the nature of astringency loss of the fruit, namely pollination constant non-astringent (PCNA), pollination variant non-astringent (PVNA), pollination variant astringent (PVA), and pollination constant astringent (PCA). Among these four types, PCNA is the most important cultivar for persimmon breeding due to the stable loss of natural astringency on the tree. The trait of natural astringency loss is recessive in Japanese PCNA cultivars, while that in the Chinese PCNA cultivar, ‘Luo tian tian shi’, is dominant and the latter locus, termed CPCNA, is different from that in Japanese cultivars. In order to develop a molecular marker for the selection of the CPCNA-type cultivar, we performed amplified fragment length polymorphism (AFLP) in combination with bulked segregant analysis for F1 offspring derived from ‘Luo tian tian shi’, which was used as the maternal parent. A total of 384 primer combinations were tested, and three AFLP markers, namely EACT-MCCC-222 (RO1), EGGC-MCTC-309 (RO2), and EGCC-MCGA-105 (RO3), linked to the CPCNA dominant allele were obtained. Among these markers, EGGC/MCTC-309 (RO2) was converted into a sequence-characterized amplified region (SCAR) marker. PCR analysis using F1 offspring (n = 264) revealed that the relevance ratio of the SCAR marker was 94%. The polymorphism of the RO2 marker, which was strongly linked to the CPCNA dominant allele, was detected in only two Chinese PCNA cultivars, namely ‘Luo tian tian shi’ and ‘Tian bao gai’, among the Chinese, Korean, and Japanese cultivars tested. These results indicate that the RO2 marker contributes to marker-assisted selection for breeding programs of new PCNA cultivars having the CPCNA trait.
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molecular identification of 1 cys peroxiredoxin and anthocyanidin flavonol 3 o galactosyltransferase from proanthocyanidin rich young fruits of persimmon diospyros kaki thunb
Planta, 2009Co-Authors: Keizo Yonemori, Akihiko Sato, Masahiko Yamada, Ayako Ikegami, Akira Kitajima, Takashi Akagi, Daniel Potter, Kentaro InoueAbstract:Fruits of persimmon (Diospyros kaki Thunb.) accumulate large amounts of proanthocyanidins (PAs) in the early stages of development. Astringent (A)-type fruits remain rich in soluble PAs even after they reach full-mature stage, whereas non-astringent (NA)-type fruits lose these compounds before full maturation. As a first step to elucidate the mechanism of PA accumulation in this non-model species, we used suppression subtractive hybridization to identify transcripts accumulating differently in young fruits of A- and NA-type. Interestingly, only a few clones involved in PA biosynthesis were identified in A–NA libraries. Represented by multiple clones were those encoding a novel 1-Cys peroxiredoxin and a new member of family 1 glycosyltransferases. Quantitative RT-PCR analyses confirmed correlation of the amount of PAs and accumulation of transcripts encoding these proteins in young persimmon fruits. Furthermore, the new family 1 glycosyltransferase was produced in Escherichia coli and shown to efficiently catalyze galactosylation at 3-hydroxyl groups of several anthocyanidins and flavonols. These findings suggest a complex mechanism of PA accumulation in persimmon fruits.
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segregations of astringent progenies in the f1 populations derived from crosses between a chinese pollination constant nonastringent pcna luo tian tian shi and japanese pcna and pollination constant astringent pca cultivars of japanese origin
Hortscience, 2006Co-Authors: Ayako Ikegami, Keizo Yonemori, Akihiko Sato, Masahiko Yamada, Sai Eguchi, Nobuhito Mitani, Akira KitajimaAbstract:Pollination-constant and nonastringent (PCNA) is one of the most desirable traits in persimmons as this type of cultivar loses its astringency while still on the tree before harvest. Among Japanese PCNA cultivars, the trait is qualitatively inherited and recessive to pollination-constant, astringent (PCA), pollination-variant, nonastringent (PVNA), and pollination-variant, astringent (PVA) types. However, in a previous trial, both astringent and nonastringent types segregated in the F 1 population that resulted from a cross between a Chinese PCNA 'Luo Tian Tian Shi' and a Japanese PCNA cultivar. Because of the unusual segregation, in this study, we crossed another Japanese PCNA 'Okugosho' with 'Luo Tian Tian Shi' to confi rm the segregation of astringent types by measuring the tannin cell size and tannin concentration at harvest. Previously, we found that astringent types have larger tannin cells than PCNA-type. The F 1 hybrid progenies from the cross segregated into both PCNA and astringent-type individuals in approximately 1:1 ratio. Likewise, the F 1 population from the astringent-type 'Yotsumizo' and 'Iwasedo' × 'Luo Tian Tian Shi' were ascertained to contain both PCNA and astringent types, which indicates that the PCNA trait of 'Luo Tian Tian Shi' was dominant. Thus, this Chinese cultivar has the potential to become an important parental material for future breeding of PCNA persimmons. Persimmon (Diosypyros kaki Persimmon (Diosypyros kaki
Timo Stark - One of the best experts on this subject based on the ideXlab platform.
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application of a molecular sensory science approach to alkalized cocoa theobroma cacao structure determination and sensory activity of nonenzymatically c glycosylated flavan 3 ols
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Timo Stark, Thomas HofmannAbstract:Application of comparative taste dilution analyses on nonalkalized and alkalized cocoa powder revealed the detection of a velvety, smoothly astringent tasting fraction, which was predominantly present in the alkalized sample. LC-MS/MS analysis, 1D- and 2D-NMR, and CD spectroscopy as well as model alkalization reactions led to the unequivocal identification of the velvety, smoothly astringent molecules as a series of catechin- and epicatechin-C-glycopyranosides. Besides the previously reported (-)-epicatechin-8-C-beta-D-galactopyranoside, additional flavan-3-ol-C-glycosides, namely, (-)-epicatechin-8-C-beta-D-glucopyranoside, (-)-catechin-8-C-beta-D-glucopyranoside, (-)-catechin-6-C-beta-D-glucopyranoside, (-)-epicatechin-6-C-beta-D-glucopyranoside, (-)-catechin-8-C-beta-D-galactopyranoside, (-)-catechin-6-C-beta-D-galactopyranoside, (-)-catechin-6-C,8-C-beta-D-diglucopyranoside, (-)-epicatechin-6-C,8-C-beta-D-digalactopyranoside, (-)-catechin-6-C,8-C-beta-D-digalactopyranoside, and epicatechin-6-C,8-C-beta-D-diglucopyranoside, were identified for the first time in cocoa. Most surprisingly, these phenol glycoconjugates were demonstrated by model experiments to be formed via a novel nonenzymatic C-glycosylation of flavan-3-ols. Using the recently developed half-tongue test, human recognition thresholds for the astringent and mouth-drying oral sensation were determined to be between 1.1 and 99.5 micro mol/L (water) depending on the sugar and the intramolecular binding position as well as the aglycone.
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Molecular definition of the taste of roasted cocoa nibs (Theobroma cacao) by means of quantitative studies and sensory experiments
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Timo Stark, Sabine Bareuther, Thomas HofmannAbstract:Sensory-guided decomposition of roasted cocoa nibs revealed that, besides theobromine and caffeine, a series of bitter-tasting 2,5-diketopiperazines and flavan-3-ols were the key inducers of the bitter taste as well as the astringent mouthfeel imparted upon consumption of roasted cocoa. In addition, a number of polyphenol glycopyranosides as well as a series of N-phenylpropenoyl-l-amino acids have been identified as key astringent compounds of roasted cocoa. In the present investigation, a total of 84 putative taste compounds were quantified in roasted cocoa beans and then rated for the taste contribution on the basis of dose-over-threshold (DoT) factors to bridge the gap between pure structural chemistry and human taste perception. To verify these quantitative results, an aqueous taste reconstitute was prepared by blending aqueous solutions of the individual taste compounds in their "natural" concentrations. Sensory analyses revealed that the taste profile of this artificial cocktail was very close to the taste profile of an aqueous suspension of roasted cocoa nibs. To further narrow down the number of key taste compounds, finally, taste omission experiments and human dose/response functions were performed, demonstrating that the bitter-tasting alkaloids theobromine and caffeine, seven bitter-tasting diketopiperazines, seven bitter- and astringent-tasting flavan-3-ols, six puckering astringent N-phenylpropenoyl-l-amino acids, four velvety astringent flavonol glycosides, gamma-aminobutyric acid, beta-aminoisobutyric acid, and six organic acids are the key organoleptics of the roasted cocoa nibs.
Akihiko Sato - One of the best experts on this subject based on the ideXlab platform.
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persimmon breeding in japan for pollination constant non astringent pcna type with marker assisted selection
Breeding Science, 2016Co-Authors: Akihiko Sato, Masahiko YamadaAbstract:Oriental persimmon (Diospyros kaki) originated in Eastern Asia, and many indigenous cultivars have been developed in China, Japan, and Korea. These cultivars are classified into four groups based on their natural astringency loss on the tree and seed formation: pollination-constant non-astringent (PCNA), pollination-variant non-astringent (PVNA), pollination-constant astringent (PCA), and pollination-variant astringent (PVA). PCNA is the most desirable type because the fruit can be eaten without any postharvest treatment; therefore, one of the goals of our persimmon breeding programs is to release superior PCNA cultivars. The PCNA genotype is recessive to the other three non-PCNA genotypes, and PCNA-type F1 offspring are obtained exclusively from crosses among PCNA genotypes. Moreover, the number of superior PCNA cross-parents have been limited. In the late 1980s, inbreeding depression became obvious, especially in terms of fruit size, tree vigor, and productivity. To mitigate the inbreeding, a backcross program using PCNA [(non-PCNA × PCNA) × PCNA] was started in 1990. This process, however, was inefficient because only 15% of the offspring were PCNA, and all offspring had to be grown to the fruiting stage. Therefore, molecular markers linked to the PCNA locus were developed for discriminating PCNA offspring. A molecular marker linked to Chinese PCNA has also been developed.
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relationships among asian persimmon cultivars astringent and non astringent types
Tree Genetics & Genomes, 2015Co-Authors: Dan E Parfitt, Keizo Yonemori, Chitose Honsho, Mitsunori Nozaka, Shinya Kanzaki, Akihiko Sato, Masahiko YamadaAbstract:A molecular marker analysis for Asian persimmon cultivar relationships and pollination status was conducted with 496 amplified fragment length polymorphism (AFLP) markers and 146 cultivars of Asian origin. Cultivars from China, Korea, and Japan were evaluated for marker composition and pollination status, which strongly influences fruit characteristics. Separation of Chinese, Korean, and Japanese cultivar groups and pollination type by neighbor-joining clustering, multidimensional scaling, and STRUCTURE was only weakly supported and not genetically significant. Significant differences for cultivar origin and pollination status were found for analysis of molecular variance (AMOVA), but most of the variation was among cultivars, not classification groups. All of the cultivar groups were genetically similar at the molecular level with most polymorphism due to individual cultivar differences.
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development of molecular markers linked to the allele associated with the non astringent trait of the chinese persimmon diospyros kaki thunb
Journal of The Japanese Society for Horticultural Science, 2011Co-Authors: Ayako Ikegami, Shinya Kanzaki, Akihiko Sato, Masahiko Yamada, Sai Eguchi, Akira Kitajima, Takashi Akagi, Keizo YonemoriAbstract:Persimmon cultivars are classified into four types depending on the nature of astringency loss of the fruit, namely pollination constant non-astringent (PCNA), pollination variant non-astringent (PVNA), pollination variant astringent (PVA), and pollination constant astringent (PCA). Among these four types, PCNA is the most important cultivar for persimmon breeding due to the stable loss of natural astringency on the tree. The trait of natural astringency loss is recessive in Japanese PCNA cultivars, while that in the Chinese PCNA cultivar, ‘Luo tian tian shi’, is dominant and the latter locus, termed CPCNA, is different from that in Japanese cultivars. In order to develop a molecular marker for the selection of the CPCNA-type cultivar, we performed amplified fragment length polymorphism (AFLP) in combination with bulked segregant analysis for F1 offspring derived from ‘Luo tian tian shi’, which was used as the maternal parent. A total of 384 primer combinations were tested, and three AFLP markers, namely EACT-MCCC-222 (RO1), EGGC-MCTC-309 (RO2), and EGCC-MCGA-105 (RO3), linked to the CPCNA dominant allele were obtained. Among these markers, EGGC/MCTC-309 (RO2) was converted into a sequence-characterized amplified region (SCAR) marker. PCR analysis using F1 offspring (n = 264) revealed that the relevance ratio of the SCAR marker was 94%. The polymorphism of the RO2 marker, which was strongly linked to the CPCNA dominant allele, was detected in only two Chinese PCNA cultivars, namely ‘Luo tian tian shi’ and ‘Tian bao gai’, among the Chinese, Korean, and Japanese cultivars tested. These results indicate that the RO2 marker contributes to marker-assisted selection for breeding programs of new PCNA cultivars having the CPCNA trait.
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molecular identification of 1 cys peroxiredoxin and anthocyanidin flavonol 3 o galactosyltransferase from proanthocyanidin rich young fruits of persimmon diospyros kaki thunb
Planta, 2009Co-Authors: Keizo Yonemori, Akihiko Sato, Masahiko Yamada, Ayako Ikegami, Akira Kitajima, Takashi Akagi, Daniel Potter, Kentaro InoueAbstract:Fruits of persimmon (Diospyros kaki Thunb.) accumulate large amounts of proanthocyanidins (PAs) in the early stages of development. Astringent (A)-type fruits remain rich in soluble PAs even after they reach full-mature stage, whereas non-astringent (NA)-type fruits lose these compounds before full maturation. As a first step to elucidate the mechanism of PA accumulation in this non-model species, we used suppression subtractive hybridization to identify transcripts accumulating differently in young fruits of A- and NA-type. Interestingly, only a few clones involved in PA biosynthesis were identified in A–NA libraries. Represented by multiple clones were those encoding a novel 1-Cys peroxiredoxin and a new member of family 1 glycosyltransferases. Quantitative RT-PCR analyses confirmed correlation of the amount of PAs and accumulation of transcripts encoding these proteins in young persimmon fruits. Furthermore, the new family 1 glycosyltransferase was produced in Escherichia coli and shown to efficiently catalyze galactosylation at 3-hydroxyl groups of several anthocyanidins and flavonols. These findings suggest a complex mechanism of PA accumulation in persimmon fruits.
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segregations of astringent progenies in the f1 populations derived from crosses between a chinese pollination constant nonastringent pcna luo tian tian shi and japanese pcna and pollination constant astringent pca cultivars of japanese origin
Hortscience, 2006Co-Authors: Ayako Ikegami, Keizo Yonemori, Akihiko Sato, Masahiko Yamada, Sai Eguchi, Nobuhito Mitani, Akira KitajimaAbstract:Pollination-constant and nonastringent (PCNA) is one of the most desirable traits in persimmons as this type of cultivar loses its astringency while still on the tree before harvest. Among Japanese PCNA cultivars, the trait is qualitatively inherited and recessive to pollination-constant, astringent (PCA), pollination-variant, nonastringent (PVNA), and pollination-variant, astringent (PVA) types. However, in a previous trial, both astringent and nonastringent types segregated in the F 1 population that resulted from a cross between a Chinese PCNA 'Luo Tian Tian Shi' and a Japanese PCNA cultivar. Because of the unusual segregation, in this study, we crossed another Japanese PCNA 'Okugosho' with 'Luo Tian Tian Shi' to confi rm the segregation of astringent types by measuring the tannin cell size and tannin concentration at harvest. Previously, we found that astringent types have larger tannin cells than PCNA-type. The F 1 hybrid progenies from the cross segregated into both PCNA and astringent-type individuals in approximately 1:1 ratio. Likewise, the F 1 population from the astringent-type 'Yotsumizo' and 'Iwasedo' × 'Luo Tian Tian Shi' were ascertained to contain both PCNA and astringent types, which indicates that the PCNA trait of 'Luo Tian Tian Shi' was dominant. Thus, this Chinese cultivar has the potential to become an important parental material for future breeding of PCNA persimmons. Persimmon (Diosypyros kaki Persimmon (Diosypyros kaki
Hidekazu Ikezaki - One of the best experts on this subject based on the ideXlab platform.
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objective evaluation methods for the bitter and astringent taste intensities of black and oolong teas by a taste sensor
Food Research International, 2013Co-Authors: Nobuyuki Hayashi, Ronggang Chen, Tomomi Ujihara, Kazue Irie, Hidekazu IkezakiAbstract:Abstract In order to objectively indicate the bitter taste intensities of black and oolong teas on the basis of a permanent standard point, a taste sensor method was developed that calibrated the sensor outputs with standard solutions prepared with only pure chemicals. Ethyl gallate (EG) was used as the standard substance. The sensor outputs were converted into the bitter taste intensities using two EG solutions at different concentrations. The astringent taste intensities of these teas were evaluated by the similar method. In this case, (−)-epigallochatechin-3-O-gallate (EGCg) was used as the standard substance. These evaluation results by the taste sensor system showed a similar tendency as those by human gustatory sense. Relative standard deviations of the sensor results revealed that these evaluation methods possessed enough practical precisions. Two-dimensional mapping analysis of the bitter and astringent taste intensities showed that, as a whole, the taste intensities of the Indian and Sri Lankan black tea samples had a tendency to be stronger than those of the Chinese oolong tea samples under the sample preparation conditions in this study.
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β cyclodextrin surface plasmon resonance detection system for sensing bitter astringent taste intensity of green tea catechins
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Nobuyuki Hayashi, Ronggang Chen, Masamitsu Hiraoka, Tomomi Ujihara, Hidekazu IkezakiAbstract:To develop a methodology for creating a sensor with a receptor for specific taste substances, we focused on constructing a sensing system for the bitter-astringent taste intensity of green tea catechins: (-)-epigallocatechin-3-O-gallate (EGCg), (-)-epicatechin-3-O-gallate (ECg), (-)-epigallocatechin (EGC), and (-)-epicatechin (EC). (1)H NMR titration experiments revealed that beta-cyclodextrin was an adequate receptor for sensing the bitter-astringent taste intensity of catechins. A surface plasmon resonance (SPR) system immobilized beta-cyclodextrin indicated larger responses for the gallate-type catechins in comparison to the non-gallate-type catechins. These responses corresponded to the tendency of the bitter-astringent taste intensity of the catechins felt by humans. Furthermore, the SPR system detected the larger stability of the complex between the gallate-type catechins and beta-cyclodextrin, which was interpreted as the aftertaste produced in humans by the gallate-type catechins. These results demonstrate that the beta-cyclodextrin/SPR system can sense the bitter-astringent taste intensity of the green tea catechins similar to human gustation. The methodology presented in this study can be used as a basic strategy for developing taste sensors with specific receptor functions.