Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/30/2003
Publication Date: 4/1/2004
Citation: Taylor, M.M., Marmer, W.N., Brown, E.M. 2004. Molecular weight distribution and functional properties of enzymatically modified commercial and experimental gelatins. Journal of American Leather Chemists Association. 99(3):129-141. Interpretive Summary: In recent years there has been much interest in the use of products from renewable resources in the production of goods traditionally made from petroleum. When hides and skins are processed into leather, a high percentage of the original substrate becomes waste, and a substantial amount of this waste can be converted into gelatin. The gelatin, when modified, has the potential for recycling into useful products. In earlier research we had shown that gelatin can be altered with an environmentally safe enzyme to give products with higher value added properties such as stronger gels that do not melt at room temperature and films that are stronger than those made from untreated gelatin. However, in this present study we targeted these modified gelatins at different mass for their adhesive, foaming and water absorption functional properties; this required a better understanding of the reaction that was taking place and this was accomplished by examining the mass distribution of the products. We found that, depending on the amount of enzyme added to the gelatin and the quality of the gelatin itself, the mass increased with a subsequent improvement not only in physical properties such as temperature tolerance and gel strength but also in functional properties. Thus, the developed enzyme treatment could increase the economical values of low quality gelatins. As an added benefit to the tanning industry, these modified gelatin products have applications as coatings or fillers that could be used in processing of hides and skins.
Technical Abstract: Prior research from this laboratory has demonstrated that commercial gelatins can be modified with a microbial transglutaminase with a resulting effect on their physical properties. The gels isolated from those treatments had improved physical properties and films prepared from these modified products had superior mechanical properties. In this present study we modified commercial gelatins and experimental gelatin products isolated from chromium-containing tannery waste and examined the functional properties as well as their molecular weight distributions. On increasing the enzyme concentration, the gelatins become highly polymerized, some to such high molecular weight that the moieties will either not go into the SDS-PAGE gel or, because of their insolubility, cannot even be applied to the gel. Physical, foaming, adhesive and water absorption properties of enzymatically-modified gelatins were improved. The extent of modification of the resulting products was demonstrated by the molecular weight distribution studies and these correlated with changes in physical and functional properties. A particular advantage to using this enzymatic modification was the improvement in physical properties imparted to low quality gelatins. The modified protein has applications in a wide range of products, including adhesives, cosmetics, films, encapsulating agents, fertilizers, and--of significance to the leather industry--as coatings or fillers.