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

Abstract

This study aimed to compare the resistance of the Oryctolagus cuniculus L. (rabbit) and Oreochromis niloticus L. (Nile tilapia) skins, as well as to observe the design of the flower of these skins and the morphology of the dermis. Tilapia and rabbit skins were placed inside the same equipment (tannery machine) for the chromium salt tanning process. The flower design of the fish leather distinguishes it from the rabbit leather, the latter being constituted by the opening of the hair follicles and pores, while the fish leather is constituted by the presence of protective lamellae and insertion of the scales. The dermis of rabbit skin consists of thick bundles of collagen fibers arranged in all directions, which differs from the morphology observed in the dermis of fish skin. However, in the Nile tilapia skin dermis, overlapping and parallel layers of longitudinal collagen fiber bundles are observed, these layers are interspersed with fiber bundles crossing the sking surface (transversely), tying the fibers together and providing greater strength, which can be proven by the strength test. The fish leathers, despite having less thickness (1.0 mm), demonstrated significantly greater tensile strength (13.52 ± 1.86 N mm−2) and tear strength (53.85 ± 6.66 N mm−2) than rabbit leathers, that is, (8.98 ± 2.67 N mm−2) and (24.25 ± 4.34 N mm−2). However, rabbit leather demonstrated higher elasticity (109.97 ± 13.52%) compared to Nile tilapia leather (78.97 ± 8.40%). It can be concluded that although the rabbit leather is thicker due to the histological architecture of the dermis (thick bundles of collagen fibers arranged in all directions with no pattern of organization of collagen fibers), it shows less resistance than Nile tilapia leather, which demonstrates an organization of overlapping and parallel layers and intercalating collagen fiber bundles transversally to the surface, functioning as tendons for the swimming process. It is recommended to use a piece of fabric (lining) together with the fleshy side of the rabbit leather, to increase resistance when used in clothing and footwear, as these products require greater tensile strength. Thus, it minimizes this restriction for the use of rabbit leather in the aforementioned purposes.

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

“…For leather traction, despite the diagonal direction shown less resistance, the average value of leather traction was 12.29 N mm -2 . These resistance values are much lower than those of other leathers reported by Oliveira et al 27 Despite the greater thickness of paiche leather, Nile tilapia (22.17 N mm -2 ), cachara Pseudoplatystoma fasciatum (21.04 N mm -2 ) and salmon (18.21 N mm -2 ) leathers were more strength, and these leathers were 80.39, 71.20 and 48.17%, respectively, more strength than paiche leather.…”

“…Concerning leather elasticity, despite paiche leather shown greater elasticity in the transverse direction (86.20%), the average leather elasticity was 68.81%, a value higher than those reported by Matiucci et al, 58 for Nile tilapia (52.63%), pacu (72.50%) and tambaqui (66.69%) leathers, which was the closest to average elasticity value of paiche leather. However, leathers with greater elasticity were observed by Oliveira et al 27 These authors reported that Nile tilapia (108.43%) and salmon (111.00%) leathers showed a high elongation value resulting from action of fatliquoring, providing greater resistance and elongation (elasticity) in the leather, improving characteristics physicomechanical properties of this leather. In research by Franco et al 59 and Oliveira et al 27 the ratio of oil used by leather thickness was 9.33, while in this study with paiche, despite a higher percentage of oil used in the fatliquoring stage, when observed the ratio with leather thickness was much lower (4/13).…”

“…However, leathers with greater elasticity were observed by Oliveira et al 27 These authors reported that Nile tilapia (108.43%) and salmon (111.00%) leathers showed a high elongation value resulting from action of fatliquoring, providing greater resistance and elongation (elasticity) in the leather, improving characteristics physicomechanical properties of this leather. In research by Franco et al 59 and Oliveira et al 27 the ratio of oil used by leather thickness was 9.33, while in this study with paiche, despite a higher percentage of oil used in the fatliquoring stage, when observed the ratio with leather thickness was much lower (4/13). Therefore, the greater amount of oil fixed on leather as a function of its thickness, the better elasticity results.…”

“…Granulometry of fish flours is directly related to equipment used for crushing, the drying quality and reduction of fat in the raw material. However, it is known that the smaller the particle size, the greater and faster the absorption by body, 27 in addition to ease of inclusion in food products without its perception. In this paiche fillets, a total pf 19 amino acids were identified, of which 10 are essential, as well in spine and head flour.…”

“…To determine Mean Geometric Diameter (MGD), the method for determining the granulometry of ingredients for use in swine and poultry rations was used. 27 For colorimetry, luminosity (L) values were evaluated using a colorimeter (MINOLTA CR-10, Minolta Camera CO, Osaka, Japan), where L* defines luminosity (L*=0 black and L*=100 white), a* (redgreen component) and b* (yellow-blue component) by CIELAB color system. 28 Microbiological analyzes were performed for the most probable number (MPN) of coliforms at 35°C and 40°C, counts of Staphylococcus coagulase positive in CFU g -1 and of Salmonella spp., according to APHA.…”