Assessment of the change in the conformation and content of collagen of the goat skin due to different unhairing process

Abstract

Recently, more attention has paid to the reduction of environmental pollution due to leather processing, the beamhouse step especially unhairing part has been named as the one which contribute high pollutants in the total industrial waste. Therefore, different types of unhairing have been studied intending to reduce waste produced by unhairing step, however, no more findings on the influence of those alternatives to the collagen of the skin which determine the features of the leather. This study explores the impacts of those unhairing alternatives to the collagen of the skin. The shrinkage temperature values were lower as compared to that of raw skin sample, where oxidative unhaired skin, shows high difference (50.5⁰C) from raw skin sample which was 64.9⁰C. There were no significant differences in the hydroxyproline concentration between unhairing, this was due to triple helix structure of the collagen which make it more stable and not easily destroyed by unhairing chemicals.  FT-IR results shows the differences in intensity (percentage) for side chain of collagen, where raw sample was 99.67%, oxidative was 90.83% while for conventional, hair saves and painting were 97.38%, 97.93% and 96.02% respectively. The stretching of N-H bond and bending for C-N bond for amide II, displays vibrations with wavenumber of 1519.20cm^-1 for oxidative unhaired wet blue, as compared to other unhaired wet blue and raw skin sample which reads at 1539.20cm^-1. The small differences in strength of the leather produced were associated with the change in the side chain intensity and conformation of collagen. The strength properties of the leather do not depend only on the concentration of the collagen but also on the proper packing of the collagen structures. The disturbance occurs to the hierarchical network of the collagen was reflected in the physical properties of the leather.