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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.
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.
Elza Fani Castrovidaurre - One of the best experts on this subject based on the ideXlab platform.
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comparison of the performance of ultrafiltration and nanofiltration membranes for recovery and recycle of Tannins in the leather industry
Journal of Cleaner Production, 2016Co-Authors: Estela Maria Romerodondiz, Jorge Emilio Almazan, Veronica B Rajal, Elza Fani CastrovidaurreAbstract:Abstract The tanning industries are characterized by generating large volumes of wastewater. The largest volume of effluents comes from the tanning stage and has a high concentration of Tannins and a low ratio tannin/non-tannin (T/NT). Membrane processes are appropriate technologies for treating these effluents. The aim of this study was to evaluate the performance of polymeric membranes in the treatment of exhausted vegetable tannin liquor from a tanning industry for its reuse. Different ultrafiltration (UF) and nanofiltration (NF) membranes were tested. Permeate flux decline, fouling resistances, fouling index, rejection for tannin (T) and non-tannin (NT) and increasing of the T/NT ratio in the retentate stream were evaluated. NF membranes had better characteristics than those of UF. The MPF-34 membrane showed the best separation properties with an increasing of the T/NT ratio from 1.68 to 1.80, for a volume reduction factor of 1.04. DK presented the best permeation properties and the lowest fouling, with an average permeate flux of 17.17 L/(m 2 h) and a fouling index ( I f ) of 27.3%. The results were promising, so this clean technology could be implemented to minimize the negative environmental impact caused by tanning industry.
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removal of vegetable Tannins to recover water in the leather industry by ultrafiltration polymeric membranes
Chemical Engineering Research & Design, 2015Co-Authors: Estela Maria Romerodondiz, Jorge Emilio Almazan, Veronica B Rajal, Elza Fani CastrovidaurreAbstract:Abstract The leather tanning industry consumes large amounts of water and produces, consequently, significant volumes of wastewater with high concentration of chemicals and organic matter. One of the main chemicals present in effluents is the vegetable tannin, which causes a severe environmental impact. With the aim of predicting the performance in chemicals separation of two ultrafiltration (UF) polymeric membranes (OT050 and GR60PP) for potential use in the purification of the waste stream of vegetable tanning liquors, a synthetic wastewater was prepared. Trials were carried out at laboratory scale using a flat cell with an effective area of 0.004 m 2 . The effect of transmembrane pressure in the permeate flux was studied. Flux decline, fouling resistance and fouling index of the membranes were analyzed. The efficiency of different membranes was assessed using the rejection coefficient for Tannins, non-Tannins and total solids. Analysis of the wastewater treated by UF showed 83% of tannin retention and a recovery of the water flux after cleaning the membrane GR60PP with water of 41–45%. The rejection coefficient observed for the GR60PP membrane was higher than for the OT050. There are no previous studies related to the removal of vegetable Tannins in exhausted vegetable tanning bath by using UF polymeric membranes. This study sets a precedent because the results obtained are very promising regarding permeate flux and rejection observed.
Remigio Lopezsolis - One of the best experts on this subject based on the ideXlab platform.
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interactions of enological Tannins with the protein fraction of saliva and astringency perception are affected by ph
Lwt - Food Science and Technology, 2012Co-Authors: Elias Obrequeslier, Alvaro Penaneira, Remigio LopezsolisAbstract:Abstract The effects of pH on both tannin-induced astringency and tannin–salivary protein interactions were investigated. A trained sensory panel evaluated astringency perception. Tannin–salivary protein interactions were assessed in vitro by examining the effects of either a condensed enological tannin or an hydrolyzable enological tannin on two physicochemical properties of the protein fraction of saliva, namely, its mode of diffusion on cellulose membranes and its precipitation. Comparative assays mimicking the degree of dilution experienced by saliva during a tasting assay were performed at pH 3.5 and pH 7.0. Results indicated that both enological Tannins were perceived as clearly more astringent at pH 3.5 compared with pH 7.0. In addition, the effects of Tannins on protein diffusion and protein precipitation were markedly exacerbated at pH 3.5.
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enhancement of both salivary protein enological tannin interactions and astringency perception by ethanol
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Elias Obrequeslier, Alvaro Penaneira, Remigio LopezsolisAbstract:Red wine astringency has been associated with interactions of Tannins with salivary proteins. Tannins are active protein precipitants. Not much evidence exists demonstrating contribution of other wine components to astringency. We aimed to investigate an eventual role of ethanol both in astringency and salivary protein−enological tannin interactions. A trained sensory panel scored perceived astringency. Salivary protein−tannin interactions were assessed by observing both tannin-dependent changes in salivary protein diffusion on cellulose membranes and tannin-induced salivary protein precipitation. Proanthocyanidins and galloTannins in aqueous and hydroalcoholic solutions were assayed. A biphasic mode of diffusion on cellulose membranes displayed by salivary proteins was unaffected after dilution with water or enological concentrations of ethanol. At those concentrations ethanol was not astringent. In aqueous solution, Tannins provoked both restriction of salivary protein diffusion, protein precipitation, ...
Eckhard Weidner - One of the best experts on this subject based on the ideXlab platform.
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screening of european medicinal herbs on their tannin content new potential tanning agents for the leather industry
Industrial Crops and Products, 2017Co-Authors: M Maier, Manfred Renner, Annaluisa Oelbermann, Eckhard WeidnerAbstract:Abstract This work addresses European medicinal herbs as possible resources for vegetable Tannins and their usage in leather production but also for further applications such as in the food, pharmaceutical or chemical industry. A detailed review of literature was conducted to identify herbs with promising tannin contents. 47 European medicinal herbs were identified for further analysis. Two plants from Rosaceae ( Potentilla erecta and Geum urbanum ) and one from Ericaceae ( Arctostaphylus uva-ursi ) show the highest tannin contents between 15 w% and 30 w% in literature. To verify the data from literature the identified 47 herbs were extracted and analyzed on their tannin content per plant by the radial diffusion method. 16 plants interfered with the radial diffusion method. Maximum tannin content per plant of 11,6 w% and maximum tannin content per dried extract of 38,4°w% were analyzed for Rubi fruticosus . For six plants of the sixteen plants it was possible to confirm the tannin contents from literature ( Alchemilla vulgaris, Acrtostaphylus uva-ursi, Fragaria, Potentilla anserine, Potentilla erecta and Rubi fruticosus ). For the remaining seven plants, lower tannin contents were obtained than listed in literature ( Geum urbanum, Melissa officinalis, Mentha piperita, Origanum vulgare, Rubi idaei, Salicis folium and Vaccinium vitis-idaea ). In the end, those six plants were evaluated on their theoretical availability in Germany as resource for new tanning agents. Fragaria, Alchemilla vulgaris and Rubi fruticosus showed the highest potential for application in leather production and for further applications. Highest amount of vegetable tannin extracts – up to 1900 kg/ha was estimated for Alchemilla vulgaris .
