Submitted to: American Leather Chemists Association Meeting
Publication Type: Proceedings
Publication Acceptance Date: 5/5/2007
Publication Date: 6/20/2007
Citation: Marmer, W.N., Dudley, R.L. 2007. Oxidative dehairing: To relime or not to relime. In: Proceedings of International Union of Leather Technologists and Chemists Societies and American Leather Chemists Association Conference, June 20-24, 2007, Washington, D.C. 2007 CDROM. Interpretive Summary:
Technical Abstract: Reliming serves several purposes and traditionally immediately follows the removal of hair (liming/dehairing; 2% sodium sulfide, 2% lime, and 1% sodium carbonate are used at ERRC). Reliming lowers the pH of the hide and opens up the collagen fibers, allowing the uptake of both calcium and water. The opening up of the collagen fibers also aids in the removal of non-collagenous proteins and any residual sulfide. The oxidative protocols that we have developed for the tannery usually use 4% sodium hydroxide. This concentration of base is sufficient to open the collagen fiber and there is an uptake of water by the hide during the dehairing process. Is this opening up of the fiber during dehairing sufficient for the removal of the non-collagenous proteins? We have extracted proteins from cattle hide using each of these four solutions: 2% lime, 0.1 and 0.01% NaOH and 4 M guanidine. All four mixtures extracted bovalbumin, bovine d2bdu (a bovine allergen) and bovallergin NID. Additional proteins were extracted; they were all bovine serum albumins; no other non-collagenous proteins were isolated. From the limited data we conclude that hides oxidatively dehaired do not require a relime step.