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Preparation and characterization of polyphenol-modified gelatin products

Taylor, M.M., Lee, J., Bumanlag, L.P., Latona, R.J., Brown, E.M., Liu, C.K.
The Journal of the American Leather Chemists Association. 2012 v.107 no.2 pp. 51
byproducts, gelatin, leather, mechanical properties, melting point, molecular weight, physical properties, plant extracts, polyphenols, product quality, tanning, tanning agents, tannins, vegetables
We have demonstrated the effectiveness of enzymatic and chemical modification of waste protein from leather, used alone or in combination with protein from the dairy industry, in preparation of fillers for leather treatment. We are continuing to build on these techniques to make products from sustainable resources that can enhance retanned leather. Vegetable tanning, utilizing polyphenols extracted from plant materials, is used primarily for production of heavy leathers for saddles, belts and shoe soles. Recently, the polyphenolic acids involved in vegetable tannage have been investigated extensively for their ability to modify gelatin. We explored whether gelatin, when modified using polyphenols, could give products with properties that might have application in leather processing. In our initial studies, before we investigated individual polyphenolic acids, we tested tannins, e.g. quebracho, to see if indeed these vegetable tannins themselves could be used in crosslinking. These studies demonstrated that gelatin could be modified, using quebracho, to make products that had varying physical properties such as high melting points and viscosities and that molecular weight determinations showed an extensive alteration in gelatin profile. These products were applied to blue stock as fillers and the resultant leather showed improved subjective properties and no significant differences in mechanical properties between treated and control samples. Thus a byproduct (gelatin) from leather-making process, modified with a common polyphenolic tanning agent (quebracho), can be employed to improve crust leather products in the retanning, coloring and fatliquoring process.