Abstract
The objective of this study was to evaluate antioxidant and metal chelating activities of leather protein hydrolysates (LPHs). The hydrolysates were produced from chrome-containing leather waste (CCLW) by alkaline hydrolysis (CaO or KOH) and enzymatic hydrolysis (Protease or trypsin). Degree of hydrolysis (DH), total amino acid content, amino acid composition, DPPH radical scavenging and iron and copper chelating activities of each hydrolysate were determined. Results showed that the highest DH percentage was recorded with LPH by CaO treatment (46.86%) and followed by KOH treatment (31.81%) then protease treatment (1.04%) and trypsin treatment (0.57%). The LPH obtained by CaO treatment contained the highest concentration of free amino acids (246.65 mg/g waste) and the highest Fe+2 chelating activity (85.54% at concentration 0.20 mg/ml) compared with the other treatments. The LPH obtained by enzymatic hydrolysis possessed the higher DPPH scavenging and Cu2+ chelating activities than LPH obtained by alkaline hydrolysis. It was concluded that the alkaline hydrolysis is a suitable and economically beneficial method to produce LPH. The LPH is an economic and natural source of amino acids and good antioxidant and metal chelating agents in plant and animal nutrition.