Evaluation of leather obtained from Cachama Negra fish skin (Colossoma macropomum) using tannins extracted from pseudostem of banana (Musa paradisiaca)

Abstract

Tannins are phenolic compounds of great economic and ecological interest, with various uses among which are natural tanning of skins, which help to minimize the environmental impact caused by the indiscriminate use of chromium. For this reason, in this research, it was proposed to extract, quantify and evaluate tanning effect of tannins on the skin of fish of the species cachama (Colossoma macropomum), extracted from the sap of the pseudostem of banana (Musa paradisiaca) in a state of senescence. For this, extractions were made with different concentrations of solvent Sap/Ethanol/Water varying its temperature (4 and 30 °C) with the purpose of finding the best ratio of solvents to optimize extraction of tannins. It was found that the optimal tannins extraction temperature of the pseudostem was at 4 °C with a ratio 1:1 Sap/Ethanol. The extract obtained was analyzed by a qualitative test to show the presence of condensed tannins in the pseudostem in a state of senescence. The quantification of tannins was performed by UV-Vis spectrophotometry analysis using Folin Ciocalteu method at a measurement of 280 nm, obtaining a maximum concentration of 12,27 g/L equivalent to gallic acid (EAG). The process of tanning in cachama fish skin (Colossoma macropomum) was performed, where physical-mechanical properties of the leather obtained were determined as tensile strength (26,3 MPa), elongation percentage (91,2 %), tear resistance (58,6 N), shrinkage temperature (62 °C), distension (13,72 mm) and breakage (53,16 daN), comparing the quality of tanning with vegetable tannin extracts of the pseudostem with industrial tanning with chromium (wet blue). It was found that the pseudostem extract can be a potential substitute to chromium salts, allowing tannery processes with similar properties and with less environmental impact.