ALCA abstracts for centenary conference

5 March 2004

ke decorin, dermatan sulfate, chondroitinsulfate and hyaluronic acid to name the most important ones. Besides those mainly proteolytic components the hide fat and lipids are by far the single biggest mass contributor next to collagen itself . In leather processing the steps until tanning mainly deal with the removal and / or modification of theses components. This has a direct impact on important leather characteristsics . One of them is the useable area of leather or better the size of the so called flanks or outer parts of a hide which often lead to downgrading. Important parameters and technologies are discussed which have a positive impact on useable area of leather by still maintaining other quality characteristics like softness , grain aspect and uniformity of the coloring. Mechanisms and Benefits of Upgrading Technologies in Finishing Loyd J. Burcham, Ph.D. TFL - New Castle Plant TFL USA/Canada, Inc. Upgrading of leather crusts that have been damaged by hide defects such as tick bites, scars, and other imperfections remains a high priority in leather finishing that enables manufacturers to improve the overall quality of their finished leather. The present study examines a series of upgrading technologies, including reverse roll-coating, hand stuccoes, and others, and compares these methods to traditional non-upgraded base/top systems. Both full-grain and corrected-grain crust are studied. As a first objective, the comparative benefits of the various systems will be determined using physical testing, visual appearance, and other performance measures. The second objective of this study is to analyze the tested and untested leathers using analytical techniques such as SEM and optical microscopy, thermal analysis, FTIR, and other methods in order to assess the finish coating morphologies and damage mechanisms associated with failures. Finally, recommendations will be made based on these results to identify the best conditions for use of the upgrading technologies investigated. An Approach to Negate Quality Problems in the Beamhouse Authors: Dr. Thomas Feigel and Mr Martin Heise TRUMPLER GmbH & Co. KG, Worms, Germany The authors offer some 'proved-in-practice' hints how some of the most typical quality problems that could be related to the beamhouse might be avoided or at least reduced in the production from green to blue. They try to give a survey over these problems, offering possible solutions that are based on experience in production. The major problems which will be discussed are veininess, abrasion, fold marks, drawn grain and residual hair. Immunochemical Estimation of the Decorin Core-Protein Content of Preparations of Bovine Decorin by Samuel M. Mozersky, Renee J. Wildermuth and William N. Marmer USDA, ARS, Eastern Regional Research Center, Wyndmoor, PA An indirect sandwich ELISA procedure has been developed for estimation of the decorin core-protein content of preparations of bovine decorin. A mouse anti-bovine decorin antibody is used as the capture antibody, and a rabbit anti-bovine decorin antibody as the detecting antibody. Goat anti-rabbit immunoglobulin G (IgG) labeled with horseradish peroxidase is used to react with the detecting antibody. The peroxidase substrate ortho-phenylenediamine (OPD), when exposed to the (bound) enzyme in the presence of peroxide, yields a soluble product with an absorbance maximum (in acidic medium) at 492 nm. The absorbance of the solution at this wavelength thus reflects the amount of decorin core-protein in the decorin preparation that is recognized by both the capture antibody and the detecting antibody. Approach to a Tanning Mechanism: Study of the Interaction of Aluminum Sulfate with Collagen by Eleanor M. Brown and Robert L. Dudley USDA, ARS, Eastern Regional Research Center, Wyndmoor, PA The production of leather from animal hides or skins is accomplished through the use of tanning agents that stabilize the collagen matrix. The molecular characteristics of tanning agents are quite varied, and led to the expectation that leathers produced with different tanning agents would have fundamentally different structures. Current proposals suggest that the structural similarities between leathers produced with different tanning agents are likely to be greater than the differences. The goal of this work is to contribute to the elucidation of a general mechanism for tanning. Although complex salts of Cr(III) are currently the most effective tanning agents, salts of other metals, including aluminum, have been used either alone or in combination with vegetable tannins or other organic chemicals. In the present study, the interaction of aluminum sulfate with collagen is investigated. In a model system, using soluble collagen, 13C NMR spectroscopy showed that Al(III) formed a complex with carboxyl groups on collagen. 27Al NMR revealed the formation of a second sphere complex between collagen and aluminum. The effects of Al(III) binding on the thermal stability of collagen were studied by circular dichroism spectroscopy of soluble complexes and differential scanning calorimetry of insoluble complexes. Comparison of Al(III)-collagen interactions with Cr(III)-collagen interactions is expected to provide insight into a more generalized mechanism for tanning. Glutaraldehyde-Tanned Leather Treated with Tocopherols by Cheng Kung Liu, Nicholas P. Latona and Joseph Lee USDA, ARS, Eastern Regional Research Center, Wyndmoor, PA Non-chrome-tanned (chrome-free) leather has gradually gained commercial importance, particularly for automobile upholstery applications. UV and heat resistance are very important qualities for automobile applications. We have made efforts to develop an environmentally friendly finishing process that will improve the UV- and heat resistance of automobile upholstery leather. Tocopherols are potent free radical scavengers and highly protective agents for collagen fibers against UV damage. We previously reported the application of tocopherols to the grain layer in order to improve the durability of chrome-tanned leather. The current study is focusing on non-chrome-tanned leather made with a glutaraldehyde-tanning process. We conducted experiments applying tocopherols to the grain layer of leather. We also studied the addition of tocopherols to the fatliquoring drums. The treated samples were exposed in a Fadeometer and then evaluated for the efficacy of UV- and heat resistance as well as the mechanical properties. Data showed that leather coated with tocopherols resulted in significant improvement in tensile strength retention and color fading resistance against UV-radiation and heat. The leather fatliquored with tocopherols, however, did not show a similar improvement. Rapid Oxidative Dehairing: Recycling of the Dehairing Reagents by Robert L. Dudley and William N. Marmer USDA, ARS, Eastern Regional Research Center, Wyndmoor, PA There is continuing interest by the packing industry in the use of rapid dehairing as a pathogen reduction step. Any such procedure must not compromise the quality of the resulting hides. We have been developing sulfide-free, oxidative processes for rapid dehairing. Recycling of the oxidative dehairing mixture is required for the protocol to be a commercially viable option. In lab-scale experiments using a peroxide/cyanate system, we successfully recycled our dehairing agent 5 to 7 times. A number of factors eventually affected the agent's efficacy. NaOH, KOCN, and H2O2 were consumed and solubilized protein began to interfere as a buffer, dropping the pH below 13 after 7 to 9 recycles. The hydrogen peroxide concentration dramatically dropped during the first three cycles of the dehairing solution and then remained at a constant but still effective concentration of 1-2 ppm. The protein concentration was dependent upon the length of the hair, but generally after three cycles the concentration was approximately 24 to 40 g/L. Removal of the insoluble hair (roughly 60% of the protein in the waste stream) did not affect the efficacy of the dehairing solution, but somewhat higher H2O2 concentrations (>10 ppm) could be maintained when the solids were removed. A Comparison Of Chemical, Physical And Enzymatic Cross-Linking Of Bovine Type I Collagen Fibrils Andrew Lastowka, Gennaro J. Maffia, Department of Chemical Engineering, Widener University, Chester, PA 19013, Eleanor M. Brown, USDA, ARS, Eastern Regional Research Center, Wyndmoor, PA 19038 Collagen fibrils are recovered from bovine corium by aggressive ball milling in dilute solutions. This is the initial step in the formation of collagen dispersions, which are used in environmental remediation and biotechnology. In this project, ball milled bovine type I collagen was treated with glutaraldehyde, dehydrothermal drying and microbial transglutaminase to promote inter- and intra-molecular cross-linked fibrils. Each sample was subjected to free amine analysis, SDS-PAGE and enzymatic degradation to determine extent of reaction, molecular weight distribution, and toughness of material. Results are presented showing the differences between the different methods of cross- linking.

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