Development and characterization of cuttlefish (Sepia officinalis) skin gelatin-protein isolate blend films

In the present study, cuttlefish skin gelatin (CSG) and protein isolate (CSPI) blend films were prepared and their physicochemical and antioxidant properties were characterized. CSG (4%, w/v) was blended with CSPI (3%, w/v) at different ratios and 15% of glycerol (w/w, plasticizer/polymer dry matter). Results showed that increasing of CSPI content induced lower lightness but higher redness, yellowness and color difference values compared to CSG film. In addition, CSPI film had the lowest tensile strength (TS) and elongation at break (EAB) values. The FTIR spectra of blend films showed a shift in the position of peaks related to the amide-I group, suggesting that they were involved in the interaction between the biopolymers. The structural properties evaluated by DSC showed a total miscibility between both polymers. This result was also confirmed by the SEM study, revealing a compact and homogenous structure in the blend films. Moreover, the water contact angle decreased in blend films, especially for those having higher proportion of CSPI. The antioxidant activity of films was markedly favored by the CSPI incorporation. Therefore, CSPI addition into gelatin matrix allowed to improve the blend films properties, mainly governed by the CSG/CSPI ratio.