Effects of bleaching on characteristics and gelling property of gelatin from splendid squid (Loligo formosana) skin

Gelatins obtained from splendid squid (Loligo formosana) skin subjected to bleaching using hydrogen peroxide (H₂O₂) at various concentrations were characterised. Yield of gelatin increased with increasing H₂O₂ concentration used. Gelatin from skin bleached with higher H₂O₂ concentrations had the lower free amino group and carbonyl group contents than the control gelatin (without bleaching). Gelatins had α-chains with MW of 123-129 kDa as the major components. FTIR spectra of all gelatins revealed the significant loss of triple-helix. Gel strength of gelatin generally decreased as H₂O₂ concentrations increased. Varying pHs rendering net charge of zero (5.18-6.34) were found among samples, as determined by z-potential titration. Gelatin prepared from skin bleached with 2% H₂O₂ showed the highest L*, but lowest ΔE*-values, compared with others. H₂O₂ at higher concentrations yielded gelatin with increasing b*-value. Thus, the properties of gelatin were governed by bleaching process, particularly H₂O₂ concentration.