Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2012
Publication Date: 1/1/2013
Citation: Taylor, M.M., Lee, J.E., Bumanlag, L.P., Latona, R.J., Brown, E.M., Liu, C. 2013. Preparation and evaluation of tara-modified proteins. Journal of American Leather Chemists Association. 108(1):16-22.
Interpretive Summary: We have demonstrated that leather quality could be improved by using fillers produced from proteins from sustainable resources that have been either enzymatically or chemically modified. These proteins may come from the leather industry (gelatin) or from the dairy industry (whey protein concentrate). As we continue our research into use of sustainable resources, we are building on these and additional techniques to make products that could enhance finished leather. In a recent study we have used the vegetable tannin quebracho to modify gelatin and make fillers that when applied to leather gave products that had improved subjective and mechanical properties. In this ongoing study we used tara, a vegetable tannin extracted from the pods of a small tree grown in Peru. The advantage for using this compound to treat the proteins is that it gives a light colored product and it is a truly sustainable resource. We modified both gelatin and whey protein concentrate and found that the resulting physical properties of the products (gel strength, melting point and/or viscosity), would make them amenable to be used as fillers. Thus gelatin and WPC, byproducts from the leather and dairy industry, modified with tara, a commonly used tanning agent, exhibited characteristics which potentially enable them to be used as fillers in the leather making process.
Technical Abstract: Quebracho, a vegetable tannin, can be used to modify gelatin to produce a product that has been applied effectively as a filler in leather processing, as described in our previous report. In this ongoing study, another vegetable tannin tara is examined for its possible application in protein modification. The tara tanning substance is a gallotannin, comprised mainly of gallic acid, and is extracted from the pods of the small tara tree (caesalpinia spinosa); it is a native plant species of Peru. Advantages for using tara are that it not only gives an almost colorless product, which would be desirable in production of light colored leather, it imparts light-fastness to the resultant leather, but is a truly sustainable resource. We examined the possibility of using both tara and its main component, the polyphenolic gallic acid, as crosslinking agents for gelatin and whey protein concentrate (WPC). Protein modification parameters were developed, and the results of product characterization using physicochemical analyses, showed that products had improved physical properties and the molecular weight distribution indicated that the bands indicative of gelatin and whey had been altered suggesting higher molecular weight moieties. Thus, by-products from the leather and dairy industry, modified by using a sustainable resource, have the potential to be used in leather processing, specifically as fillers.