Collagen and polyphenols : new relationship and new outcomes. Part 1. Flavonoid reactions for new tanning processes / Anthony D. Covington in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 9 (09/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 9 (09/2005) . - p. 325-335 Titre : Collagen and polyphenols : new relationship and new outcomes. Part 1. Flavonoid reactions for new tanning processes Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; L. Song, Auteur ; T. H. Lilley, Auteur Année de publication : 2005 Article en page(s) : p. 325-335 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The process of vegetable tanning is hindered by the astringency of the tannins, which affects the development of their use as organic tanning agents for modern purposes. The use of non tans, either from natural sources such as green tea or by degrading tannins into non tannins, avoids the problem of hindered penetration through pelt due to the high reactivity of the polyphenols. Both tannins and non tannins are capable of engaging in combination tannage with aldehydic agents, to confer high hydrothermal stability to collagen. The use of prodelphinidin or prorobinetinidin polyphenols, characterized by the presence of a pyrogallol B-ring, is preferred in this context. Also, the use of non tannins provides a practical route to modem organic tanning. En ligne : https://drive.google.com/file/d/15iPRhEGaqXGcbGEUN68FWrIxyzBvussz/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4054 [article]

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Collagen and polyphenols : new relationships and new outcomes. Part 2. Phenolic reactions for simultaneous tanning and coloring / Anthony D. Covington in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 9 (09/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 9 (09/2005) . - p. 336-343 Titre : Collagen and polyphenols : new relationships and new outcomes. Part 2. Phenolic reactions for simultaneous tanning and coloring Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; Ono Suparno, Auteur ; T. H. Lilley, Auteur ; C. S. Evans, Auteur Année de publication : 2005 Article en page(s) : p. 336-343 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Polyphenols are the basic building blocks of natural skin and hair pigments: they can be polymerised to create versions of natural black, brown and orange melanins. These reactions can be catalysed by laccase: not only dothey create colour, but also, if they are conducted in the presence of collagen, the resulting pigment is bound to the leather in a covalent tanning manner. Therefore, the leather becomes coloured by a lightfast pigment, which is firmly fixed. It has not proved possible to create a pure black, but earth shades from green to brown/black are easily produced. It appears to be a feature of this type of stabilising mechanism for collagen, the creation of a polyphenol matrix around the triple helix, that it has the added benefit of actually strengthening the leather. Since every traditional process step effectively weakens collagen, especially tanning, this is the first chemical reaction that has been shown to reverse that effect. En ligne : https://drive.google.com/file/d/1Sex4BZgd7gbc5qBoke0HQi9MOb0bDntG/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4055 [article]

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