The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Thomas Hofmann - One of the best experts on this subject based on the ideXlab platform.
-
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-...
-
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.
-
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.
-
Effect of Astringent Stimuli on Salivary Protein Interactions Elucidated by Complementary Proteomics Approaches.
Journal of Agricultural and Food Chemistry, 2017Co-Authors: Judith Delius, Guillaume Médard, Bernhard Kuster, Thomas HofmannAbstract:The interaction of Astringent substances with salivary proteins, which results in protein precipitation, is considered a key event in the molecular mechanism underlying the oral sensation of puckering astringency. As the chemical nature of orally active Astringents is diverse and the knowledge of their interactions with salivary proteins rather fragmentary, human whole saliva samples were incubated with suprathreshold and isointensity solutions of the Astringent polyphenol (−)-epigallocatechin gallate, the multivalent metal salt iron(III) sulfate, the amino-functionalized polysaccharide chitosan, and the basic protein lysozyme. After separation of the precipitated proteins, the proteins affected by the Astringents were identified and relatively quantified for the first time by complementary bottom-up and top-down mass spectrometry-based proteomics approaches. Major salivary target proteins, which may be involved in astringency perception, are reported here for each Astringent stimulus.
-
orosensory directed identification of Astringent mouthfeel and bitter tasting compounds in red wine
Journal of Agricultural and Food Chemistry, 2008Co-Authors: Jan Carlos Hufnagel, Thomas HofmannAbstract:Application of sequential solvent extraction, followed by HPLC combined with the taste dilution analysis, enabled the localization of the most intense velvety Astringent, drying, and puckering Astringent, as well as bitter-tasting, compounds in red wine, respectively. Isolation of the taste components involving gel adsorption chromatography, ultrafiltration, and synthesis revealed the identification of 26 sensory-active nonvolatiles, among which several hydroxybenzoic acids, hydroxycinnamic acids, flavon-3-ol glycosides, and dihydroflavon-3-ol rhamnosides as well as a structurally undefined polymeric fraction (>5 kDa) were identified as the key Astringent components. In contradiction to literature suggestions, flavan-3-ols were found to be not of major importance for astringency and bitter taste, respectively. Surprisingly, a series of hydroxybenzoic acid ethyl esters and hydroxycinnamic acid ethyl esters were identified as bitter compounds in wine. Taste qualities and taste threshold concentrations of th...
Erminio Monteleone - One of the best experts on this subject based on the ideXlab platform.
-
saliva characteristics and individual sensitivity to phenolic Astringent stimuli
Chemical Senses, 2009Co-Authors: Caterina Dinnella, Annamaria Recchia, Giovanna Fia, Mario Bertuccioli, Erminio MonteleoneAbstract:Astringency sensation is due to interactions between salivary proteins and phenols and is based on an increased-friction mechanism. Modifications to the profile of salivary proteins and their concentration could affect tannin/protein reactions and hence the intensity of perceived astringency. Salivary characteristics of 65 subjects were compared after abstention from phenol-containing food and immediately after ingestion of tannic acid. The effect of stimulation on saliva characteristics was expressed in terms of D value, computed as the arithmetic difference between values found in saliva samples from the 2 conditions. Based on D values, subjects were clustered in two groups. Cluster 1 (Cl1, 53 cases) was characterized by low D values thus indicating that the basal saliva condition was quickly restored in these subjects. Cluster 2 (Cl2) was composed of 12 subjects whose basal salivary condition was not quickly restored, particularly in terms of salivary protein concentration and profile and saliva haze-forming capacity. Sensory data showed that subjects capable of maintaining constant saliva characteristics were less sensitive to Astringent stimuli than subjects in which the same stimulations induced significant saliva modifications. The results suggest that a large proportion of the population are able to maintain their salivary protein concentration and simultaneously intercept and inactivate dietary tannins.
-
Temporary modification of salivary protein profile and individual responses to repeated phenolic Astringent stimuli
Chemical Senses, 2009Co-Authors: Caterina Dinnella, Annamaria Recchia, Hely Tuorila, Simone Vincenzi, Erminio MonteleoneAbstract:The extent of the change in salivary protein characteristics after repeated stimulations was shown to be correlated to differences in perceived astringency. Salivary characteristics of 77 subjects were compared after masticatory (S1) and taste/masticatory (S2) stimulations. The variations (S2 minus S1) of protein concentration and saliva haze-forming capacity (HFC) were used to define 3 subject groups: low responding (LR, n = 20), medium responding (MR, n = 37), and high responding (HR, n = 20). Salivary protein concentration did not change in LR subjects; decreased a little, but significantly, in MR subjects; and strongly decreased in HR subjects. After S2, HFC increased in LR subjects, slightly decreased in MR subjects, and strongly decreased in HR subjects. Salivary protein electrophoresis patterns for HR and LR subjects were analyzed. No significant modifications of glycosylated proline-rich proteins (PRPs), PRPs, and amylases and a slight decrease in cystatins and histatins were found when S2 and S1 samples were compared in LR subjects, whereas HR subjects showed a strong decrease in all the above proteins after S2. Significant modifications of mucins were not found. Tannic acid (TA, 3 g/L) astringency ratings after S1 from HR subjects were significantly higher than those from the other 2 groups, whereas no differences were found comparing LR and MR ratings. The "carryover" effect due to 4 sequential exposures to TA samples (1.4 g/L) was observed in both HR and MR groups, whereas no significant astringency rating variation was found in the LR group. The results support the inhibiting role of proteins with strong phenol-binding activity on astringency elicitation. Individual physiological variations of parotid gland functionality might account for differences in sensitivity to Astringent phenolic stimuli.
Gerald G Fuller - One of the best experts on this subject based on the ideXlab platform.
-
interaction of human whole saliva and Astringent dietary compounds investigated by interfacial shear rheology
Food Hydrocolloids, 2008Co-Authors: D Rossetti, Gleb E Yakubov, Jason R Stokes, Annmarie Williamson, Gerald G FullerAbstract:Human whole saliva (HWS) is a complex physiological secretion that performs a number of essential functions such as protection of oral health, lubrication of mouth tissues, as well as predigestion of food. In addition, saliva forms the perireceptor environment of the oral cavity and, by its interactions with food and beverages, influences the transduction of aroma, taste and tactile (mouthfeel) perceptions. We investigate and report the impact of addition of compounds commonly found in oral health and beverage products (sodium dodecyl sulphate (SDS), citric acid and tea polyphenols: epigallocatechin gallate (EGCG), epicatechin (EC), rutin) on the interfacial shear elasticity of HWS obtained from a single subject. The aim of this work is to probe the relationship between surface shear elasticity of saliva and the Astringent (puckering-like) mouthfeel arising from the consumption of products containing the investigated ingredients. Saliva proteins are extremely surface active and adsorb to the air-liquid interface to form a high-elastic "solid-like" surface film. Our findings show that the interfacial shear elasticity G of saliva is significantly reduced when mixed with citric acid, SDS or a tea polyphenol containing a galloyl ring in the molecule (EGCG). These results support the hypothesis that astringency arises from aggregation of salivary proteins, thereby reducing lubrication of oral tissues. Minor or no effect is observed from the interaction of saliva with EC or rutin. Furthermore, we investigate the possibility of using mucins as a simple model for saliva. Two selected mucins, tested at different concentrations and ionic strength, failed to mimic the elastic interfacial behaviour shown by saliva. (C) 2007 Elsevier Ltd. All rights reserved.
-
interaction of human whole saliva and Astringent dietary compounds investigated by interfacial shear rheology
Food Hydrocolloids, 2008Co-Authors: D Rossetti, Gleb E Yakubov, Jason R Stokes, Annmarie Williamson, Gerald G FullerAbstract:Human whole saliva (HWS) is a complex physiological secretion that performs a number of essential functions such as protection of oral health, lubrication of mouth tissues, as well as predigestion of food. In addition, saliva forms the perireceptor environment of the oral cavity and, by its interactions with food and beverages, influences the transduction of aroma, taste and tactile (mouthfeel) perceptions. We investigate and report the impact of addition of compounds commonly found in oral health and beverage products (sodium dodecyl sulphate (SDS), citric acid and tea polyphenols: epigallocatechin gallate (EGCG), epicatechin (EC), rutin) on the interfacial shear elasticity of HWS obtained from a single subject. The aim of this work is to probe the relationship between surface shear elasticity of saliva and the Astringent (puckering-like) mouthfeel arising from the consumption of products containing the investigated ingredients. Saliva proteins are extremely surface active and adsorb to the air-liquid interface to form a high-elastic "solid-like" surface film. Our findings show that the interfacial shear elasticity G of saliva is significantly reduced when mixed with citric acid, SDS or a tea polyphenol containing a galloyl ring in the molecule (EGCG). These results support the hypothesis that astringency arises from aggregation of salivary proteins, thereby reducing lubrication of oral tissues. Minor or no effect is observed from the interaction of saliva with EC or rutin. Furthermore, we investigate the possibility of using mucins as a simple model for saliva. Two selected mucins, tested at different concentrations and ionic strength, failed to mimic the elastic interfacial behaviour shown by saliva. (C) 2007 Elsevier Ltd. All rights reserved.
Michael N Clifford - One of the best experts on this subject based on the ideXlab platform.
-
evidence that salivary proteins are involved in astringency
Journal of Sensory Studies, 1998Co-Authors: S Kallithraka, J Bakker, Michael N CliffordAbstract:Proteins in saliva samples taken from twelve subjects immediately before and immediately after tasting Astringent solutions were analyzed by high performance liquid chromatography. Although considerable variation in both the qualitative and quantitative protein pattern was observed among individuals, three peaks appeared to be common to the majority of the chromatograms. The tasting of the Astringent solutions resulted in detectable changes in the protein profile of the saliva samples, observed in all the chromatograms examined, and attributed to the interactions of the saliva proteins with the Astringent phenolic compounds. The appearance of a major peak at 8 min after the tasting of the Astringent compounds common to most of the saliva chromatograms was attributed to the formation of soluble protein-phenol complexes.
Caterina Dinnella - One of the best experts on this subject based on the ideXlab platform.
-
saliva characteristics and individual sensitivity to phenolic Astringent stimuli
Chemical Senses, 2009Co-Authors: Caterina Dinnella, Annamaria Recchia, Giovanna Fia, Mario Bertuccioli, Erminio MonteleoneAbstract:Astringency sensation is due to interactions between salivary proteins and phenols and is based on an increased-friction mechanism. Modifications to the profile of salivary proteins and their concentration could affect tannin/protein reactions and hence the intensity of perceived astringency. Salivary characteristics of 65 subjects were compared after abstention from phenol-containing food and immediately after ingestion of tannic acid. The effect of stimulation on saliva characteristics was expressed in terms of D value, computed as the arithmetic difference between values found in saliva samples from the 2 conditions. Based on D values, subjects were clustered in two groups. Cluster 1 (Cl1, 53 cases) was characterized by low D values thus indicating that the basal saliva condition was quickly restored in these subjects. Cluster 2 (Cl2) was composed of 12 subjects whose basal salivary condition was not quickly restored, particularly in terms of salivary protein concentration and profile and saliva haze-forming capacity. Sensory data showed that subjects capable of maintaining constant saliva characteristics were less sensitive to Astringent stimuli than subjects in which the same stimulations induced significant saliva modifications. The results suggest that a large proportion of the population are able to maintain their salivary protein concentration and simultaneously intercept and inactivate dietary tannins.
-
Temporary modification of salivary protein profile and individual responses to repeated phenolic Astringent stimuli
Chemical Senses, 2009Co-Authors: Caterina Dinnella, Annamaria Recchia, Hely Tuorila, Simone Vincenzi, Erminio MonteleoneAbstract:The extent of the change in salivary protein characteristics after repeated stimulations was shown to be correlated to differences in perceived astringency. Salivary characteristics of 77 subjects were compared after masticatory (S1) and taste/masticatory (S2) stimulations. The variations (S2 minus S1) of protein concentration and saliva haze-forming capacity (HFC) were used to define 3 subject groups: low responding (LR, n = 20), medium responding (MR, n = 37), and high responding (HR, n = 20). Salivary protein concentration did not change in LR subjects; decreased a little, but significantly, in MR subjects; and strongly decreased in HR subjects. After S2, HFC increased in LR subjects, slightly decreased in MR subjects, and strongly decreased in HR subjects. Salivary protein electrophoresis patterns for HR and LR subjects were analyzed. No significant modifications of glycosylated proline-rich proteins (PRPs), PRPs, and amylases and a slight decrease in cystatins and histatins were found when S2 and S1 samples were compared in LR subjects, whereas HR subjects showed a strong decrease in all the above proteins after S2. Significant modifications of mucins were not found. Tannic acid (TA, 3 g/L) astringency ratings after S1 from HR subjects were significantly higher than those from the other 2 groups, whereas no differences were found comparing LR and MR ratings. The "carryover" effect due to 4 sequential exposures to TA samples (1.4 g/L) was observed in both HR and MR groups, whereas no significant astringency rating variation was found in the LR group. The results support the inhibiting role of proteins with strong phenol-binding activity on astringency elicitation. Individual physiological variations of parotid gland functionality might account for differences in sensitivity to Astringent phenolic stimuli.
