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Tanins œnologiques : caractéristiques, propriétés et fonctionnalités. Impact sur la qualité des vins
No full textThe use of oenological tannins is a common practice worldwide in winemaking. However, up to date this use, is only authorized by the OIV to facilitate wines and must clarification. Nevertheless, oenological tannins are used for several reasons, explaining the existence of diverse tannins on the market. For all these reasons, OIV has begun few years ago to create a working group in order to conduct a large study on oenological tannins. Thus, the aim of this research was to carry out an exhaustive study to determine firstly the chemical composition and the richness in tannins of the oenological tannins. Secondly, their potential functionalities were studied, focusing on their antioxidant activity, their ability to stabilize and improve wine color and finally, their antioxidasic activity. Concerning chemical composition, the principal tannins monomers, dimers, trimers and tetramers were identified and quantified by HPLC-MS and LC-QTOF. The abundance in tannins was estimated by different methods: TPI, Bate-Smith, Methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The antioxidant capacity was measured 5 methods (ABTS, CUPRAC, DPPH, FRAP and ORAC) meanwhile the oxygen consumption was measured using a non-invasive method based on luminescence. Antioxidasic property, was achieved by measuring first the laccase activity in winemaking, then by determined inhibition type and finally by laccase characterization precipitation by electrophoresis SDS-PAGE. The oenological tannins ability to stabilize the color was determined by their bathochromic and hyperchromic effect and by the calculation of the copigmentation index. Their color stabilization effect was evaluated during several days, different ethanol content and pH level. The results confirm that oenological tannins and specifically, ellagitannins, really protect wine against oxidation either because they exert antioxidant capacity and/or they consume directly oxygen. Moreover, oenological tannins can improve and stabilize red wines color acting as copigments, with gallotannins being the most efficient ones. In addition, oenological tannins, particularly grapes tannins, can be a new tool to inhibit the laccases produced by B. cinerea. As a fruit of these results, the OIV resolutions OENO-TECHNO 17-612 and OENO-TECHNO 17-613, just accepted, proposed to include two new functionalities of tannins uses in musts and wines:•Contribute to the antioxidant protection of must and wine components•Promote the expression, stabilization and preservation of color.L'utilisation de tanins œnologiques en vinification relève d’une pratique courante, bien que ceux-ci ne soient à ce jour uniquement autorisés dans le but de faciliter la clarification des vins et des moûts par l’OIV. En revanche, les tanins œnologiques peuvent aussi être utilisés à d’autres fins, expliquant l’existence d’une grande variété sur le marché. En ce sens, l'OIV à créer il y a quelques années, un groupe de travail afin de conduire une vaste étude sur les tannins œnologiques. L’objectif de cette thèse était donc de mener une étude exhaustive afin de déterminer dans un premier temps leur composition chimique et leur richesse en tanins. Dans un second temps leurs potentielles fonctionnalités ont été étudiées, en mettant l'accent sur leur activité antioxydante, leur capacité à stabiliser la couleur des vins et, enfin, leur activité antioxidasique. Concernant, la composition chimique, les principaux monomères, dimères, trimères et tétramères des tanins ont été identifiés et quantifiés par HPLC-MS-UV et LC-QTOF. La richesse en tanins a été estimée par différentes méthodes : IPT, Bate-Smith, méthyl-cellulose, Folin-Ciocalteu, méthode officielle de l'OIV et phloroglucinolyse. La capacité antioxydante a été mesurée par 5 méthodes (ABTS, CUPRAC, DPPH, FRAP et ORAC), tandis que la consommation d'oxygène a été déterminée à l'aide d'une méthode non invasive basée sur la luminescence. La mesure de l’activité laccase, la détermination du type d’inhibition et la caractérisation des laccases par électrophorèse SDS-PAGE, ont permis d’évaluer les propriétés antioxidasique des tannins œnologiques. La capacité des tanins œnologiques à stabiliser la couleur a été déterminée par l’induction d’effet bathochrome et hyperchrome ainsi que par le calcul de l’indice de copigmentation. Cet effet a été évalué pendant plusieurs jours, à différentes concentrations d’ethanol et à différents pH. Les résultats obtenus confirment que les tanins œnologiques et plus particulièrement les ellagitannins protègent le vin de l'oxydation, de par leur pouvoir antioxydant et capacité à consommer directement l’oxygène. Les tanins œnologiques, et plus particulièrement les gallotannins, permettent de stabiliser la couleur des vins rouges, en jouant le rôle de copigments. Enfin, les tanins œnologiques, et en particulier les tanins du raisin, constituent un nouvel outil afin d’inhiber ou précipiter les laccases produites par B. cinerea. Fruit de ces résultats, les résolutions de l'OIV OENO-TECHNO 17-612 et OENO-TECHNO 17-613, récemment acceptées, proposent d'inclure deux nouvelles fonctionnalités d'utilisation des tanins dans les moûts et les vins :• Contribuer à la protection antioxydante des composants du moût et du vin• Promouvoir l'expression, la stabilisation et la préservation de la couleu
Oenological Tannins : characteristics, properties and functionalities. Impact on wine quality.
No full textL'utilisation de tanins œnologiques en vinification relève d’une pratique courante, bien que ceux-ci ne soient à ce jour uniquement autorisés dans le but de faciliter la clarification des vins et des moûts par l’OIV. En revanche, les tanins œnologiques peuvent aussi être utilisés à d’autres fins, expliquant l’existence d’une grande variété sur le marché. En ce sens, l'OIV à créer il y a quelques années, un groupe de travail afin de conduire une vaste étude sur les tannins œnologiques. L’objectif de cette thèse était donc de mener une étude exhaustive afin de déterminer dans un premier temps leur composition chimique et leur richesse en tanins. Dans un second temps leurs potentielles fonctionnalités ont été étudiées, en mettant l'accent sur leur activité antioxydante, leur capacité à stabiliser la couleur des vins et, enfin, leur activité antioxidasique. Concernant, la composition chimique, les principaux monomères, dimères, trimères et tétramères des tanins ont été identifiés et quantifiés par HPLC-MS-UV et LC-QTOF. La richesse en tanins a été estimée par différentes méthodes : IPT, Bate-Smith, méthyl-cellulose, Folin-Ciocalteu, méthode officielle de l'OIV et phloroglucinolyse. La capacité antioxydante a été mesurée par 5 méthodes (ABTS, CUPRAC, DPPH, FRAP et ORAC), tandis que la consommation d'oxygène a été déterminée à l'aide d'une méthode non invasive basée sur la luminescence. La mesure de l’activité laccase, la détermination du type d’inhibition et la caractérisation des laccases par électrophorèse SDS-PAGE, ont permis d’évaluer les propriétés antioxidasique des tannins œnologiques. La capacité des tanins œnologiques à stabiliser la couleur a été déterminée par l’induction d’effet bathochrome et hyperchrome ainsi que par le calcul de l’indice de copigmentation. Cet effet a été évalué pendant plusieurs jours, à différentes concentrations d’ethanol et à différents pH. Les résultats obtenus confirment que les tanins œnologiques et plus particulièrement les ellagitannins protègent le vin de l'oxydation, de par leur pouvoir antioxydant et capacité à consommer directement l’oxygène. Les tanins œnologiques, et plus particulièrement les gallotannins, permettent de stabiliser la couleur des vins rouges, en jouant le rôle de copigments. Enfin, les tanins œnologiques, et en particulier les tanins du raisin, constituent un nouvel outil afin d’inhiber ou précipiter les laccases produites par B. cinerea. Fruit de ces résultats, les résolutions de l'OIV OENO-TECHNO 17-612 et OENO-TECHNO 17-613, récemment acceptées, proposent d'inclure deux nouvelles fonctionnalités d'utilisation des tanins dans les moûts et les vins :• Contribuer à la protection antioxydante des composants du moût et du vin• Promouvoir l'expression, la stabilisation et la préservation de la couleurThe use of oenological tannins is a common practice worldwide in winemaking. However, up to date this use, is only authorized by the OIV to facilitate wines and must clarification. Nevertheless, oenological tannins are used for several reasons, explaining the existence of diverse tannins on the market. For all these reasons, OIV has begun few years ago to create a working group in order to conduct a large study on oenological tannins. Thus, the aim of this research was to carry out an exhaustive study to determine firstly the chemical composition and the richness in tannins of the oenological tannins. Secondly, their potential functionalities were studied, focusing on their antioxidant activity, their ability to stabilize and improve wine color and finally, their antioxidasic activity. Concerning chemical composition, the principal tannins monomers, dimers, trimers and tetramers were identified and quantified by HPLC-MS and LC-QTOF. The abundance in tannins was estimated by different methods: TPI, Bate-Smith, Methyl-cellulose, Folin-Ciocalteu, OIV official method and phloroglucinolisis. The antioxidant capacity was measured 5 methods (ABTS, CUPRAC, DPPH, FRAP and ORAC) meanwhile the oxygen consumption was measured using a non-invasive method based on luminescence. Antioxidasic property, was achieved by measuring first the laccase activity in winemaking, then by determined inhibition type and finally by laccase characterization precipitation by electrophoresis SDS-PAGE. The oenological tannins ability to stabilize the color was determined by their bathochromic and hyperchromic effect and by the calculation of the copigmentation index. Their color stabilization effect was evaluated during several days, different ethanol content and pH level. The results confirm that oenological tannins and specifically, ellagitannins, really protect wine against oxidation either because they exert antioxidant capacity and/or they consume directly oxygen. Moreover, oenological tannins can improve and stabilize red wines color acting as copigments, with gallotannins being the most efficient ones. In addition, oenological tannins, particularly grapes tannins, can be a new tool to inhibit the laccases produced by B. cinerea. As a fruit of these results, the OIV resolutions OENO-TECHNO 17-612 and OENO-TECHNO 17-613, just accepted, proposed to include two new functionalities of tannins uses in musts and wines:• Contribute to the antioxidant protection of must and wine components• Promote the expression, stabilization and preservation of color
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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