Genipin-Modified Gelatin: Preparation, Characterization, and Application as a Filler for Leather

Genipin, an iridoid compound extracted from gardenia fruits (Gardenia jasminoides Ellis) is a natural crosslinking agent. Because of its low cytotoxicity, genipin is increasingly used to replace both glutaraldehyde and formaldehyde as a crosslinker for proteins. Researchers have in recent years successfully demonstrated the effective use of genipin in the modification of gelatin, particularly for its use in biomedical products. We have recently reported the appropriate conditions (i.e., temperature, pH and concentration) necessary for reaction of genipin with powdered and intact hides. In this present study, we applied those reported conditions to gelatin. We investigated the crosslinking capability of genipin with gelatin to identify the parameters necessary to obtain products that could be used as fillers in leather processing. The crosslinked products should preferably possess physical properties that are compatible with the temperatures used during leather processing (28-50°C). We next applied the appropriate products to blue stock before we retanned, colored and fatliquored the hides. The properties and quality of the resultant leather were then evaluated. Using epi-fluorescent microscopy, we verified that the genipincrosslinked gelatin was uniformly distributed through the blue stock and was not removed during washing; furthermore, Scanning Electron Microscopy (SEM) showed that the fibers appeared to be coated with the product. The physical properties of the genipin/gelatin products, as well as mechanical properties and subjective evaluation of the treated, final crust leather, will be presented along with representative epifluorescent microscopy and SEM images. Based on these results, we propose that genipin-modified gelatin has the potential to provide an environmentally safe alternative to the more conventional post tanning processes.