Characterisation of gelatin–fatty acid emulsion films based on blue shark (Prionace glauca) skin gelatin

Incorporation of fatty acids (stearic and oleic) into edible films based on blue shark (Prionace glauca) skin gelatin was investigated to modify properties such as water vapour barrier and flexibility due to their hydrophobicity and plasticizing effect, respectively. Addition of stearic acid from 0% to 100% of protein concentration in the film-forming solution considerably decreased water vapour permeability of gelatin–fatty acid emulsion films compared to addition of oleic acid at the same fatty acid concentration. Increasing concentrations of both fatty acids decreased tensile strength, but increased elongation at break due to their plasticizing effect. At the same concentration, oleic acid gave a greater plasticizing effect than did stearic acid. On the other hand, transparency of the gelatin–stearic acid emulsion film was lower than that of the gelatin–oleic acid emulsion film. Faster stirring speed of homogenisation improved properties of only the gelatin–stearic acid emulsion film.