Tanned leather of the paiche Arapaima gigas Schinz, 1822 (Arapaimidae) with extracts of vegetable origin to replace chromium salts

Abstract

With the intensification of fish farming, the amount of residues also increased. One of the by-products generated is leather. However, several factors influence its quality, among them, the types of tanning used. Paiche (Arapaima gigas) is the largest freshwater fish in the world, and therefore has great potential in the use of leather, in addition to being one of the most cultivated fish in the Rondônia state. The aimed was to evaluate the physicomechanical resistance, histological and morphological aspects in different directions of the fibers of the paiche to evaluate the tanning with chromium oxide and vegetable tannin. Paiches with an average weight of 12.0 kg were used, skins were made and tanned using chromium and vegetable tannin as techniques. After tanning, 20 specimens were removed in longitudinal, transverse and diagonal directions to the fish body, to determine resistance in dynamometer and leather for histological analysis, scanning electron microscopy and physical-chemical analysis. The average thickness of the specimens of the leathers ranged 1.79mm to 2.82mm, in addition, there was no interaction between the type of tanning agent and the directions obtained for strength, traction and elongation. Regarding the progressive tearing test, there was also no interaction effect. However, the defined factors had relevant differences for the maximum and average amount applied, and the leathers tanned with vegetable tannin expanded to larger dimensions 110.19 and 85.52 N. According to the images obtained by histology and scanning microscopy, they presented that in the longitudinal and transverse direction the collagen fibers are presented in layers parallel to the leather surface and in the diagonal direction the interlacing is more intense, that is, in addition to the overlapping layers intercalated thinner, close to the surface, fiber bundles can also be seen crossing each other. It is concluded that leathers tanned with vegetable tannin have less resistance than leathers tanned with chromium salts for traction to rupture and greater resistance to tear.

Characterization and Strength Quality of the Oryctolagus cuniculus Leather Compared to Oreochromis niloticus Leather

“…When addressing the tanning technique, it may refer to any of the stages of the process or chemicals used, as well as their concentration. Among the products, the use of chromium salts provides a lower thickness compared to those tanned with vegetable tannin [8,22], and the use of liming agents, as they are responsible for opening and eliminating the interfibrillar material, also reduces the thickness of the leather [23]. e purging step interferes directly with the thickness of the leather, because in this step the proteolytic enzymes act on undesirable proteins, to promote better opening and help penetration of other chemicals, thus reducing thickness [9].…”

“…Rabbit skin is a by-product that can be processed with or without hair to obtain, after a tanning process, a raw material with high softness, elasticity, and beauty, for its softness to the touch and with an extremely delicate flower design (surface of the skin without hair) [6,7]. After the tanning process, the leather is transformed into a beautiful product when well-handled during rearing and slaughter and can be directed to the different tanning techniques, and the two results, with or without hair, are excellent in terms of final raw material, differentiating in the aspect of its applicability in clothing, mainly in the article [8]. However, these leathers are currently being discarded or underutilized due to the lack of proper tanning techniques, and preservation and storage systems [1,4].…”

Yield and chemical composition in Arapaima gigas fillets, reuse of by-products for flour make and quality of vegetable tannin-tanned leathers

“…52 These high values are due to type of fatty acids contained in feed that the fish receives, especially from freshwater, where there is a greater amount of omega 6. 53 In contrast to what was discussed above, Cavali et al 17,36 report that the western population has a very high omega 6 /omega 3 ratio, reaching 20-30/1. According to these authors, this high ratio is related to multiplicity of vegetable oils available and currently consumed by this population, as they are rich in omega 6.…”

“…15 However, paiche is a species that needs a year of cultivation to reach slaughter weight, that is, for commercialization, with good management and feeding. 17 Although, Nile tilapia reaches the ideal weight for slaughter in 3 to 4 months with a weight of 600 to 800g. 20 However, the high yield of the paiche fillet did not exceed the yield found for the same species, from extractive fishing or capture from natural environment, which obtained 57% of meat yield.…”

“…They are superimposed layers of collagen fibers intertwined with each other that provide the highest resistance of the leather when subjected to vegetable tannin tanning. 17 According to Souza et al 19 and Vilhena et al 18 the way in which the fibers are arranged in the histological architecture of the skin is possible to determine greater resistance of the leathers. The thickness varies according to species, habits, and part of animal body.…”