Physical properties of edible emulsified films from pistachio oil cake globulin protein and stearic acid

Edible emulsified films were made from pistachio globulin protein (PGP) (6 g/100ml)، stearic fatty acid (SA) (2، 4 and 6% w/w protein)، glycerol (1g/1g of protein)، and emulsifier by emulsification method in order to improve water vapor permeability (WVP) and reduce water solubility of protein film. WVP of films reduced 38. 5 to 42% by fatty acid addition and water solubility decreased slightly، too. Effect of SA on the oxygen permeability (OP) of emulsified films was determined indirectly by oil peroxide value measurements. OP values of the emulsified films were lower than that of PGP film، but the differences were not significant (P>0. 05). Tensile strength (TS) and elongation at break (E) of PGP film were 9 Mega Pascal and 104%، respectively. TS and E of emulsified films were diminished 11 to 41% and 35 to 70%، respectively as a result of SA addition. Opacity of emulsified films (unfavorable sensory attribute) increased as function of SA concentration. Glass transition temperature (Tg) of films was measured by differential scanning calorimetry. Tg of PGP film was at 127. 19 °C and was not affected considerably by the SA addition.