Effect of Fillers Prepared from Enzymatically Modified Proteins on Mechanical Properties of Leather

Authors: Taylor, Maryann; Marmer, William; Brown, Eleanor - Ellie

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2007
Publication Date: 4/1/2008
Citation: Taylor, M.M., Marmer, W.N., Brown, E.M. 2008. Effect of Fillers Prepared from Enzymatically Modified Proteins on Mechanical Properties of Leather. Journal of American Leather Chemists Association. 103(4):128-137.

Interpretive Summary: The utilization of products from renewable resources, particularly those from waste proteins, has produced significant interest recently, particularly as substitutes for goods that were traditionally made from petroleum feedstuffs. Fillers, used by the leather industry to treat hides in order to give the leather more body, are examples of products that have been made from these conventional feedstuffs. As an alternative to these increasingly expensive products, we proposed and then demonstrated in previously reported research, that gelatin (a byproduct of leather production) alone or in combination with casein or whey (byproducts of the dairy industry), when reacted with a commercially available food grade enzyme, could give products that indeed filled the leather. In this present study, we scaled-up the processes, applied the products to tanned hides and then finished the hides by retanning, coloring, and adding fatliquor to make them soft. We then looked at the mechanical properties of the leather, such as how strong it was, and determined whether the added fillers changed these properties. We also subjectively evaluated the leather with respect, for example, to softness and appearance. We found, when comparing the treated leather to untreated control samples, that the mechanical properties were not adversely affected and, with respect to the subjective properties, the filled samples were improved over the untreated control samples. As a result, we have shown not only the potential of making fillers for leather from these renewable resources, but also have added value to these waste proteins.

Technical Abstract: In an environment where petroleum feedstuffs are becoming increasingly too expensive for a good cost-effective return, utilization of renewable resources makes economic sense, particularly when these substrates are waste proteins. We have thus proposed the application of enzymatically modified waste proteins from the leather (gelatin) and dairy (casein and whey) industries as fillers in leather production. In previously reported research, we prepared different combinations of these waste proteins, enzymatically modified them, characterized the products and applied them to blue stock using fluorescently labeled proteins to determine how they were distributed in the hide and more importantly not removed by washing. From the data acquired in these previous experiments, we identified potential filling materials. We now have treated various areas in the hide (butt, belly, and neck) with the products, retanned, colored and fatliquored the treated pieces, evaluated them with respect to subjective properties against controls, and finally determined mechanical properties. The results from these tests show that the mechanical properties were not significantly affected by the treatment and subjective properties, e.g., handle, fullness, break and color, were improved over the controls. Fillers thus have the potential to be economically produced from sustainable resources as an alternative to more expensive and increasingly limited conventional products.