Aspectos morfológicos da pele e avaliação qualitativa do couro de pirarara (Phractocephalus hemioliopterus, Bloch & Schneider 1801) oriundo do estado do Amazonas

Abstract

Fishing in the Amazon is characterized by the richness of exploited species, the amount of fish caught and the dependence of the local population on this activity. Studies have shown that it is important to perform the histology of architecture of the collagen fibers of the fish dermis. The fish hides are considered an alternative in the search for new byproducts that contribute to sustainable development. This work had as objective a descriptive analysis of the skin and qualitative evaluation of the pirarara from the State of Amazonas. The analyzes were UFAM's Fish Technology Laboratory, of Technology at the INPA Fur Tanning Pilot Plant, Laboratory Optical and Electronic Microscopy Thematic - LTMOE / CPAAF / INPA and Laboratory of Studies in Leather and Environment (LACOURO-RS).The results of production for pirarara, landed at different locations in the state of Amazonas, between 2001 and 2012, were 3378 t. The proximate composition of fresh skin collected during the flood (2010) and dry (2011) respectively: Humidity: 61.20% and 58.43%; Proteins: 38.29% and 42.00%; Lipids: 1.36% and 3.9%. Ashes: 0.63% and 0.67%. In fresh skin it is observed a thin epidermis and just below, a superficial dermis with chromatophores containing abundant and very evident granules of Melanin The dorsal middle region, the superficial and deep dermis composed by arrangement of type I collagen fibers arranged longitudinally, transverse and vertical. In the anterior dorsal region (dry season) and final region dorsal (flood season) there is presence of compact fibers, not presenting evidence of difference between the seasons.In the anterior dorsal region in relation to body length (time of flood), it was observed that the fibers collagens are less compact and intact and are available in angles close to 45º along the skin, intersecting with others perpendicular lines and an interlace occurs, forming long and well oriented. In the retanning / greasing stage, fibers and fibrils are observed well-individualized and spaced collagens, providing flexibility and softness to the leather. Vegetable tanning was a satisfactory result. At average thickness of the leather used for the tests of resistance to traction and stretching and for progressive tearing were 1.54 and 1.57mm. For traction and elongation, the tear strength was lower in the period of (55.63 N / mm) compared to drought (69.86 N / mm) and the maximum force was lower in the flood (80.20 N) compared to the drought (97.17 N). Only the force maximum tear - longitudinal (76.63 N) and transverse (83.77 N) - differed significantly. The comparison of flood and drought periods showed significant difference in the cuts - 19.73 and 20.09 N / mm2 for maximum tension; 62.19 and 63.30 N / mm for tear - for the senses longitudinal and transverse, respectively. As for stretching, the largest resistance was transverse (40.62%) in relation to the longitudinal (33.29%).