Physico-chemical and film forming properties of giant squid (Dosidicus gigas) gelatin

Giant squid (Dosidicus gigas) inner and outer tunics were subjected to hydrolysis with pepsin prior to gelatin extraction (G1 gelatin) by a mild-acid procedure. Furthermore, a second gelatin extraction (G2 gelatin) was done using the collagenous residues that remained from the first extraction. Pepsin allows the collagen solubilisation and the extraction yield to increase by yielding extracts high in α-chains. G1 exhibited good gel forming ability but G2 showed poor viscoelastic behaviour and low gel strength, in agreement with the results for the molecular weight distribution, which showed a considerably higher content of low molecular weight components. In spite of these differences, both G1 and G2 showed good filmogenic ability and similar properties were found including the absence of colour, opacity, low water vapour permeability and high puncture deformation. Nevertheless, films made from G1 had a higher puncture force than films made from G2 as a result of the different molecular weight distribution.