Film forming ability of gelatins from splendid squid (Loligo formosana) skin bleached with hydrogen peroxide

Properties of gelatin films from splendid squid (Loligo formosana) skin bleached with hydrogen peroxide (H₂O₂) at various concentrations (0-8% w/v) were investigated. Tensile strength (TS) and water vapour permeability (WVP) of films decreased, but elongation at break (EAB) increased (p < 0.05) as the concentration of H₂O₂ increased. Among all films, that prepared from gelatin with 2% H ₂O₂ bleaching showed the lowest ΔE ^*-value (total colour difference), which was concomitant with the highest L^*-value (lightness). Generally, higher concentration of H₂O₂ resulted in increased b ^*-value (yellowness) of resulting films. Electrophoretic study revealed that α-chains of gelatin in films became lowered with increasing H₂O₂ concentrations used for bleaching. Thermogravimetric analysis indicated that heat susceptibility and weight loss of different films varied with H₂O₂ concentrations. Rougher surface was obtained in gelatin films prepared from skin bleached with H₂O ₂ concentrations above 4%. Thus, the concentrations of H ₂O₂ used for bleaching of squid skin prior to gelatin extraction directly affected the properties of corresponding gelatin films.