Characteristics and gel properties of gelatin from goat skin as affected by pretreatments using sodium sulfate and hydrogen peroxide

BACKGROUND: Goat skin can be used as an alternative raw material for gelatin production, in which pretreatment conditions can determine the characteristics or properties of the resulting gelatin. The present study aimed to investigate the effect of pretreatment using sodium sulfate (Na₂SO₄) and hydrogen peroxide (H₂O₂) on properties of goat skin gelatin. RESULTS: Pretreatment of skin using Na₂SO₄ (0-1 mol L^-1) increased the yield of gelatin in a concentration-dependent manner. When skins with prior Na₂SO₄ treatment were bleached using H₂O₂ (0-2 mol L^-1), the resulting gelatin showed higher yield and gel strength than those without prior Na₂SO₄ treatment. All gelatins had α-chain as a major component, followed by β-chain. The degradation induced by H₂O₂ was lower in gelatin with prior Na₂SO₄ treatment. L* values increased with increasing H₂O₂ concentrations (P < 0.05) due to the bleaching effect of H₂O₂. With Na₂SO₄ and H₂O₂ pretreatments, gelatin gel had a finer and more ordered microstructure. Gelatin had an imino acid content of 217 residues/1000 residues with gelling and melting temperature of 22.49 and 32.28 °C, respectively. CONCLUSION: The optimal pretreatment conditions for gelatin extraction from goat skin included soaking the skin in 0.75 mol L^-1 NaOH, followed by treatment using 0.75 mol L^-1 Na₂SO₄ and subsequent bleaching with 2 mol L^-1 H₂O₂. This resulted in gelatin with superior quality to the untreated counterpart.