Development of a Degreasing Process for Paiche Skins (Arapaima gigas) for Tanning Preserving the Natural Pattern and Color

The utilization of Amazonian fish skins, like paiche, to obtain leather, has been gaining importance in Peru. The beauty of the pattern of this fish skin comes from its light beige color and the black strip that runs through its back. This research aimed to develop a degreasing process for the tanning of paiche skin, that allows to preserve its natural pattern and color in the finished leather. For this purpose, a mixture of degreasers, diesel oil, lipases, and surfactants was used. In tanned skins, physical-mechanical properties, such as tear strength, tensile strength, elongation percentage, and shrinkage temperature, were evaluated. The presence of fishy smell in tanned paiche skins was evaluated through an analysis of fat content, fatty acid profiles, and sensorial tests. Besides, wastewater of the process was characterized to determine BOD5, COD, TSS, oils, and greases, TPH, phenols, and pH. This wastewater was treated by a laboratory-scale system, based on sedimentation, sifting, and flocculation-coagulation. As a result, a degreasing process using 8% of diesel oil, 18% of surfactants and 1.2% of lipidic enzymes, applied in cycles before and after the pickling process, was established. This process allowed the conservation of pattern and color of skin and the reduction of polyunsaturated fatty acids that cause the fishy smell in the leather, which complied with physicalmechanical standards for making footwear, bags, and clothing. Thus, a reduction in the pollutant charge in wastewater was achieved to acceptable environmental levels.