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James A Kennedy - One of the best experts on this subject based on the ideXlab platform.
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red wine Tannin structure activity relationships during fermentation and maceration
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Ralph S Yacco, Aude A. Watrelot, James A KennedyAbstract:The correlation between Tannin structure and corresponding activity was investigated by measuring the thermodynamics of interaction between Tannins isolated from commercial red wine fermentations and a polystyrene divinylbenzene HPLC column. Must and/or wine samples were collected throughout fermentation/maceration from five Napa Valley wineries. By varying winery, fruit source, maceration time, and cap management practice, it was considered that a reasonably large variation in commercially relevant Tannin structure would result. Tannins were isolated from samples collected using low pressure chromatography and were then characterized by gel permeation chromatography and acid-catalyzed cleavage in the presence of excess phloroglucinol (phloroglucinolysis). Corresponding Tannin activity was determined using HPLC by measuring the thermodynamics of interaction between isolated Tannin and a polystyrene divinylbenzene HPLC column. This measurement approach was designed to determine the ability of Tannins to hy...
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wine and grape Tannin interactions with salivary proteins and their impact on astringency a review of current research
Molecules, 2011Co-Authors: Jacqui M. Mcrae, James A KennedyAbstract:Abstract: Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine Tannins with salivary proteins and the subsequent aggregation and precipitation of protein-Tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how Tannins impact the quality of the sensation, particularly with respect to Tannin structure. Ultimately, the understanding of how Tannin structure impacts astringency will allow the controlled manipulation of Tannins via such methods as micro-oxygenation or fining to improve the quality of wines. Keywords: astringency; condensed Tannin; salivary proteins; wine 1. Introduction Tannins, including grape-derived condensed Tannins (flavonoids) produce sensations of astringency in food and drink and form the ‘structure’ or ‘body’ of red wine. The term astringency refers to the drying and a puckering sensation in the mouth [1] and is a characteristic of red wine and its mouth-feel [2-5]. Wine Tannin quality is dependent on the maximum intensity of the mouth feel, total duration and time taken to reach maximum intensity [6], as well as the extent of mouth drying and mouth roughness [1,7,8]. The spectrum of subtle differences in astringency sensations was compiled as a ‘red wine
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Wine and grape Tannin interactions with salivary proteins and their impact on astringency: A review of current research
Molecules, 2011Co-Authors: Jacqui M. Mcrae, James A KennedyAbstract:Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine Tannins with salivary proteins and the subsequent aggregation and precipitation of protein-Tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how Tannins impact the quality of the sensation, particularly with respect to Tannin structure. Ultimately, the understanding of how Tannin structure impacts astringency will allow the controlled manipulation of Tannins via such methods as micro-oxygenation or fining to improve the quality of wines.
K Becker - One of the best experts on this subject based on the ideXlab platform.
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Tannins determined by various methods as predictors of methane production reduction potential of plants by an in vitro rumen fermentation system
Animal Feed Science and Technology, 2009Co-Authors: Anuraga Jayanegara, H P S Makkar, Norvsambuu Togtokhbayar, K BeckerAbstract:Relationships between chemical constituents, including values obtained with Tannin assays (i.e., total phenols, total Tannins, condensed Tannins and Tannin activity using a Tannin bioassay) for plant materials (n = 17), and methane production parameters at 24 h of incubation in the in vitro Hohenheim gas method were established. The methane production reduction potential (MRP) was calculated by assuming net methane concentration for the control hay as 100%. The MRP of Bergenia crassifolia leaves and roots, and Peltiphyllum peltatum leaves, was >40%. Amongst the chemical constituents, neutral detergent fibre had a high correlation (r = 0.86) with methane concentration. There was negative relationship between total phenol, total Tannins or Tannin activity and methane concentration. However, a positive relationship existed between these Tannin assays and the MRP, with r-values ranging from 0.54 to 0.79 (P<0.05). A very weak relationship (r = 0.09) occurred between condensed Tannins and MRP. Similar results to those with MRP were obtained with the percent increase in methane on addition of polyethylene glycol. The highest correlations, 0.79 and 0.92 (P<0.001), were between Tannin activity determined using the Tannin bioassay and the MRP, or the percent increase in methane on addition of polyethylene glycol, respectively, suggesting that this Tannin assay could be used to identify plants possessing antimethanogenic properties. Leaves of
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tropical browses contents of phenolic compounds in vitro gas production and stoichiometric relationship between short chain fatty acid and in vitro gas production
The Journal of Agricultural Science, 2002Co-Authors: G Getachew, Harinder P S Makkar, K BeckerAbstract:The contents of phenolic compounds, protein precipitation capacity (PPC) and in vitro gas production of tropical browse species were evaluated. The stoichiometric relationship between in vitro gas measured on incubation of Tannin-containing browses in buffered rumen fluid and calculated from short chain fatty acid (SCFA) production was investigated. Crude protein (CP) contents in the browses ranged from 54 to 300 g/kg dry matter (DM). Total phenol (TP), Tannins (T) and condensed Tannins (TP and T as tannic acid equivalent; CT, as leucocyanidin equivalent) ranged from 17–250, 7–214, and 0–260 g/kg DM respectively, and PPC from 0 to 1066 μg BSA precipitated/g DM. CP content of browses was negatively correlated with TP, T, CT and PPC. A significant correlation was observed between per cent change in gas production on addition of polyethylene glycol (PEG) and the contents of phenolics ( r = 0.76 for both TP and T). Addition of PEG to Tannin-containing browses increased in vitro gas production. PPC was significantly correlated with TP ( r = 0.87; P r = 0.83; P r = 0.41; P R 2 = 0.94; P in vitro gas production and that calculated from SCFA. The molar proportions of SCFA were not affected by the inclusion of PEG ( P >0.05). The relationship between in vitro gas measured on incubation of browse leaves and that calculated from SCFA allows prediction of SCFA from gas production.
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formation of complexes between polyvinyl pyrrolidones or polyethylene glycols and Tannins and their implication in gas production and true digestibility in in vitro techniques
British Journal of Nutrition, 1995Co-Authors: H P S Makkar, Michael Blummel, K BeckerAbstract:Various Tannin-complexing agents have been used to study the potential adverse effects of Tannins on rumen metabolism. Using a method based on turbidity formation, the binding of various Tannin-complexing agents (polyvinyl polypyrrolidone (PVPP), polyethylene glycol (PEG) of molecular weights 2000 to 35,000, and polyvinyl pyrrolidone (PVP) of molecular weight 10,000, 40,000 and 360,000) to Tannins (tannic acid, purified Tannins from quebracho (Aspidosperma quebracho) and leaves of trees and shrubs (Acioa barteri, Dichostachys cinerea, Guiera senegalensis, Piliostigma reticulatum)) was investigated at different pH values. The binding of all the Tannins with PVPP was highest at pH 3-4 and lowest at pH 7. For all the pH range (3-7) studied, the binding of PEG was higher than that of PVP. For all the Tannins except tannic acid, the binding to PVP was the same from pH 4.7 to 7. Similar results were observed for the PEG of molecular weight 6000 or higher for all the Tannins except quebracho Tannins for which the binding increased as the pH increased from 3 to 7. The binding with PEG 2000 decreased to a greater extent as the pH reached near neutral and for PEG 4000 this decrease was slightly lower. Addition of these Tannin-complexing agents to the in vitro gas system resulted in higher gas production from Tannin-rich feeds (increase varied from 0 to 135%). The PEG were the most effective followed by PVP and PVPP. The PEG 35,000 was least effective. The efficiency of other PEG was similar. The PEG 6000 was preferred to PEG 2000 or 4000 as its binding to Tannins was higher at near neutral pH values. The gas production increased with an increase in the amount of PEG 6000 up to 0.6 g/40 ml rumen-fluid-containing medium containing 0.5 g Tannin-rich feed, beyond which no increase was observed. The percentage increase in gas value at 24 h fermentation correlated significantly with Tannin values, the highest correlation (r 0.95) being with protein precipitation capacity of Tannins. The increase in gas production was associated with higher production of short-chain fatty acids with little change in their molar proportions, suggesting an increase in organic matter digestibility by inclusion of the PEG in Tannin-rich feeds. However, apparent and true digestibilities were lower on addition of the PEG, due to the presence of PEG-Tannin complexes in the residues. The use of this bioassay (percentage increase in gas production in the presence of PEG 6000) along with other Tannin assays would provide a better insight into the nutritional significance of Tannins.
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gravimetric determination of Tannins and their correlations with chemical and protein precipitation methods
Journal of the Science of Food and Agriculture, 1993Co-Authors: H P S Makkar, Michael Blummel, N K Borowy, K BeckerAbstract:Abstract. A method for gravimetric determination of Tannins based on binding with insoluble polyvinylpyrrolidone (PVP) is presented. The gravimetric method gives the absolute amount of Tannins and avoids problems of standards associated with spectrophotometric methods. The method was applied to nine browse and tree leaves. The values obtained correlate significantly with Tannins determined spectrophotometrically, protein precipitation capacities and protein precipitable phenotics. This method together with other Tannin assays will be useful in nutritional studies. The present study also demonstrates the different behaviour of tannic acids from different commercial sources towards PVP suggesting the presence of different moieties in tannic acids from different commercial sources and even among batches from the same source thereby affecting the results obtained using the spectrophotometric methods. Use of well-defined tannic acid as a standard in spectrophotometric methods is suggested which will allow meaningful comparison of values obtained from different laboratories.
Roderick I Mackie - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Mechanisms to Overcome Inhibitory Effects of Dietary Tannins
Microbial Ecology, 2005Co-Authors: Alexandra H Smith, Erwin Zoetendal, Roderick I MackieAbstract:High concentrations of Tannins in fodder plants inhibit gastrointestinal bacteria and reduce ruminant performance. Increasing the proportion of Tannin-resistant bacteria in the rumen protects ruminants from antinutritional effects. The reason for the protective effect is unclear, but could be elucidated if the mechanism(s) by which Tannins inhibit bacteria and the mechanisms of Tannin resistance were understood. A review of the literature indicates that the ability of Tannins to complex with polymers and minerals is the basis of the inhibitory effect on gastrointestinal bacteria. Mechanisms by which bacteria can overcome inhibition include Tannin modification/degradation, dissociation of Tannin–substrate complexes, Tannin inactivation by high-affinity binders, and membrane modification/repair and metal ion sequestration. Understanding the mechanism of action of Tannins and the mechanism(s) bacteria use to overcome the inhibitory effects will allow better management of the rumen ecosystem to reduce the antinutritional effects of Tannin-rich fodder plants and thereby improve ruminant production.
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effect of condensed Tannins on bacterial diversity and metabolic activity in the rat gastrointestinal tract
Applied and Environmental Microbiology, 2004Co-Authors: Alexandra H Smith, Roderick I MackieAbstract:The effect of dietary condensed Tannins (proanthocyanidins) on rat fecal bacterial populations was ascertained in order to determine whether the proportion on Tannin-resistant bacteria increased and if there was a change in the predominant bacterial populations. After 3 weeks of Tannin diets the proportion of Tannin-resistant bacteria increased significantly (P < 0.05) from 0.3% +/- 5.5% to 25.3% +/- 8.3% with a 0.7% Tannin diet and to 47.2% +/- 5.1% with a 2% Tannin diet. The proportion of Tannin-resistant bacteria returned to preexposure levels in the absence of dietary Tannins. A shift in bacterial populations was confirmed by molecular fingerprinting of fecal bacterial populations by denaturing gradient gel electrophoresis (DGGE). Posttreatment samples were generally still distinguishable from controls after 3.5 weeks. Sequence analysis of DGGE bands and characterization of Tannin-resistant isolates indicated that Tannins selected for Enterobacteriaceae and Bacteroides species. Dot blot quantification confirmed that these gram-negative bacterial groups predominated in the presence of dietary Tannins and that there was a corresponding decrease in the gram-positive Clostridium leptum group and other groups. Metabolic fingerprint patterns revealed that functional activities of culturable fecal bacteria were affected by the presence of Tannins. Condensed Tannins of Acacia angustissima altered fecal bacterial populations in the rat gastrointestinal tract, resulting in a shift in the predominant bacteria towards Tannin-resistant gram-negative Enterobacteriaceae and Bacteroides species.
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increasing the oxidative stress response allows escherichia coli to overcome inhibitory effects of condensed Tannins
Applied and Environmental Microbiology, 2003Co-Authors: Alexandra H Smith, James A Imlay, Roderick I MackieAbstract:Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of Tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed Tannins (proanthocyanidins). E. coli growth was inhibited by Tannins only when Tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was generated when they were added to aerobic media. The addition of exogenous catalase permitted growth in Tannin medium. E. coli mutants that lacked HPI, the major catalase, were especially sensitive to Tannins, while oxyR mutants that constitutively overexpress antioxidant enzymes were resistant. A Tannin-resistant mutant was isolated in which a promoter-region point mutation increased the level of HPI by 10-fold. Our results indicate that wattle condensed Tannins are toxic to E. coli in aerobic medium primarily because they generate H2O2. The oxidative stress response helps E. coli strains to overcome their inhibitory effect.
Jacqui M. Mcrae - One of the best experts on this subject based on the ideXlab platform.
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wine and grape Tannin interactions with salivary proteins and their impact on astringency a review of current research
Molecules, 2011Co-Authors: Jacqui M. Mcrae, James A KennedyAbstract:Abstract: Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine Tannins with salivary proteins and the subsequent aggregation and precipitation of protein-Tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how Tannins impact the quality of the sensation, particularly with respect to Tannin structure. Ultimately, the understanding of how Tannin structure impacts astringency will allow the controlled manipulation of Tannins via such methods as micro-oxygenation or fining to improve the quality of wines. Keywords: astringency; condensed Tannin; salivary proteins; wine 1. Introduction Tannins, including grape-derived condensed Tannins (flavonoids) produce sensations of astringency in food and drink and form the ‘structure’ or ‘body’ of red wine. The term astringency refers to the drying and a puckering sensation in the mouth [1] and is a characteristic of red wine and its mouth-feel [2-5]. Wine Tannin quality is dependent on the maximum intensity of the mouth feel, total duration and time taken to reach maximum intensity [6], as well as the extent of mouth drying and mouth roughness [1,7,8]. The spectrum of subtle differences in astringency sensations was compiled as a ‘red wine
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Wine and grape Tannin interactions with salivary proteins and their impact on astringency: A review of current research
Molecules, 2011Co-Authors: Jacqui M. Mcrae, James A KennedyAbstract:Astringency is an important characteristic of red wine quality. The sensation is generally thought to be produced by the interaction of wine Tannins with salivary proteins and the subsequent aggregation and precipitation of protein-Tannin complexes. The importance of wine astringency for marketability has led to a wealth of research on the causes of astringency and how Tannins impact the quality of the sensation, particularly with respect to Tannin structure. Ultimately, the understanding of how Tannin structure impacts astringency will allow the controlled manipulation of Tannins via such methods as micro-oxygenation or fining to improve the quality of wines.
Alexandra H Smith - One of the best experts on this subject based on the ideXlab platform.
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Bacterial Mechanisms to Overcome Inhibitory Effects of Dietary Tannins
Microbial Ecology, 2005Co-Authors: Alexandra H Smith, Erwin Zoetendal, Roderick I MackieAbstract:High concentrations of Tannins in fodder plants inhibit gastrointestinal bacteria and reduce ruminant performance. Increasing the proportion of Tannin-resistant bacteria in the rumen protects ruminants from antinutritional effects. The reason for the protective effect is unclear, but could be elucidated if the mechanism(s) by which Tannins inhibit bacteria and the mechanisms of Tannin resistance were understood. A review of the literature indicates that the ability of Tannins to complex with polymers and minerals is the basis of the inhibitory effect on gastrointestinal bacteria. Mechanisms by which bacteria can overcome inhibition include Tannin modification/degradation, dissociation of Tannin–substrate complexes, Tannin inactivation by high-affinity binders, and membrane modification/repair and metal ion sequestration. Understanding the mechanism of action of Tannins and the mechanism(s) bacteria use to overcome the inhibitory effects will allow better management of the rumen ecosystem to reduce the antinutritional effects of Tannin-rich fodder plants and thereby improve ruminant production.
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effect of condensed Tannins on bacterial diversity and metabolic activity in the rat gastrointestinal tract
Applied and Environmental Microbiology, 2004Co-Authors: Alexandra H Smith, Roderick I MackieAbstract:The effect of dietary condensed Tannins (proanthocyanidins) on rat fecal bacterial populations was ascertained in order to determine whether the proportion on Tannin-resistant bacteria increased and if there was a change in the predominant bacterial populations. After 3 weeks of Tannin diets the proportion of Tannin-resistant bacteria increased significantly (P < 0.05) from 0.3% +/- 5.5% to 25.3% +/- 8.3% with a 0.7% Tannin diet and to 47.2% +/- 5.1% with a 2% Tannin diet. The proportion of Tannin-resistant bacteria returned to preexposure levels in the absence of dietary Tannins. A shift in bacterial populations was confirmed by molecular fingerprinting of fecal bacterial populations by denaturing gradient gel electrophoresis (DGGE). Posttreatment samples were generally still distinguishable from controls after 3.5 weeks. Sequence analysis of DGGE bands and characterization of Tannin-resistant isolates indicated that Tannins selected for Enterobacteriaceae and Bacteroides species. Dot blot quantification confirmed that these gram-negative bacterial groups predominated in the presence of dietary Tannins and that there was a corresponding decrease in the gram-positive Clostridium leptum group and other groups. Metabolic fingerprint patterns revealed that functional activities of culturable fecal bacteria were affected by the presence of Tannins. Condensed Tannins of Acacia angustissima altered fecal bacterial populations in the rat gastrointestinal tract, resulting in a shift in the predominant bacteria towards Tannin-resistant gram-negative Enterobacteriaceae and Bacteroides species.
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increasing the oxidative stress response allows escherichia coli to overcome inhibitory effects of condensed Tannins
Applied and Environmental Microbiology, 2003Co-Authors: Alexandra H Smith, James A Imlay, Roderick I MackieAbstract:Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of Tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed Tannins (proanthocyanidins). E. coli growth was inhibited by Tannins only when Tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was generated when they were added to aerobic media. The addition of exogenous catalase permitted growth in Tannin medium. E. coli mutants that lacked HPI, the major catalase, were especially sensitive to Tannins, while oxyR mutants that constitutively overexpress antioxidant enzymes were resistant. A Tannin-resistant mutant was isolated in which a promoter-region point mutation increased the level of HPI by 10-fold. Our results indicate that wattle condensed Tannins are toxic to E. coli in aerobic medium primarily because they generate H2O2. The oxidative stress response helps E. coli strains to overcome their inhibitory effect.
