Investigations on determination of antioxidant properties of certain plant products and their effects on the prevention of CR(VI) and formaldehyde formation in leather

The effectiveness of antioxidant materials on the prevention of free radical formation is well known. The tannins as phenolic materials are also known to have antioxidant properties, however, the antioxidant effectiveness shows variation regarding to the type and structure of tannins. In leather manufacturing direct use of Cr(VI) and formaldehyde is forbidden, however, there is always a risk of conversion of Cr(III) to Cr(VI) and formation of free formaldehyde subsequent to the manufacturing. Free radicals usually play an important role of formation of these toxic substances in leather. In the present study, Valonea and Henna was selected as tannin and their antioxidant capacities were determined by FRAP and TEAC/ABTS methods. Furthermore, these vegetable tannins were used in leather processes and their effect on prevention of Cr(VI) and free formaldehyde formation was examined.