Evaluation of Polymers Prepared from Gelatin and Casein or Whey as Potential Fillers

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

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2006
Publication Date: 4/1/2007
Citation: Taylor, M.M., Marmer, W.N., Brown, E.M. 2007. Evaluation of Polymers Prepared from Gelatin and Casein or Whey as Potential Fillers. Journal of American Leather Chemists Association. 102(4):111-120.

Interpretive Summary: Leather fillers, which fill the hide to give a more uniform product, typically are made from petroleum-derived materials. In response to increasing demand for biobased products, we had demonstrated that a commercially available enzyme could be reacted with gelatin (a byproduct of leather production) and with casein or whey (byproducts of the dairy industry) to give biopolymers with unique properties. Based on our understanding of these reactions, we now have prepared products from a mixture of these proteins, characterized them with respect to their degree of polymerization and applied them to tanned leather for evaluation. We added a fluorescent label to the proteins before polymerization; this label can be seen in the treated leather with an appropriately equipped microscope. It was shown that these mixed polymerized proteins were evenly distributed throughout the hide and, more importantly, were not removed during the washing steps. Thus, we have added value to these waste products from various agricultural sources by making products that potentially can be used in the leather-making process.

Technical Abstract: We recently demonstrated that fillers could be formed inside leather when gelatins alone or mixed proteins, such as gelatin and casein or gelatin and whey, were added to wet blue that had been pretreated with microbial transglutaminase. To monitor these reactions, we had added fluorescently labeled proteins to stock solutions and examined the resultant filled leather using a microscope equipped with an epi-fluorescent attachment. In this present study, based on our understanding of the effect that enzyme modification will have on physical properties of crosslinked proteins, we polymerized potential filler products prior to their addition to the wet blue. We characterized the products with respect to their physical properties and molecular weight distribution (degree of polymerization). These products were applied to wet blue and evaluated, again using fluorescent labels to monitor their filling capability. It was shown that the proteins were evenly distributed throughout the hide and, more importantly, were not removed during the washing steps. Micrographs showing the location of fillers using fluorescent labels are presented.