Suitability of Fish Skins for Making Leather: The Case of Salmo salar and Lates niloticus

Abstract

Fibre structure, selected chemical and physical properties of Salmo salar (Linnaeus, 1758) and Lates niloticus (Linnaeus, 1758) skins and leathers were studied in order to establish the leathers’ suitability in the manufacture of leather products. Microscopic examination revealed that fibres run as parallel sheets in both longitudinal and transverse sections of the fish body; this arrangement is considered to contribute to the increased strength of fish leather despite being thin.  The skins’ collagen content was found to be 61.2% and 72.0% for S. salar and L. niloticus respectively implying their suitability for leather making as this is in the same range as the conventional raw materials used in the leather industry. Due to the poor hydrothermal stability of raw fish skins, the degreasing was carried on wet blue leathers. The grease content was reduced from 23.7% and 13.0% to 5.9% and 5.5% for S. salar and L. niloticus respectively. The chromic oxide content was found to be 2.98% and 2.37% for S. salar and L. niloticus respectively. Shrinkage temperature was measured using DSC and Shrinkage temperature equipment and there was a strong positive correlation between the two approaches; r2 = 0.98. The shrinkage temperature of raw skins was 43.73oC and 60.71oC while that of wet blue leathers was 77.24oC and 88.75oC for S. salar and L. niloticus respectively. The average tensile strength was 14.13 N/mm2 and 21.63 N/mm2 whereas the single-edge tear strength was 21.68 N and 132.20 N for S. salar and L. niloticus respectively. The leathers were generally well stabilized and meet the requirements for various end uses.