Mechanical and barrier properties of edible chitosan films as affected by composition and storage

Oxygen permeability coefficients (OF), water vapor permeability coefficients (WVP), ethylene permeability coefficients (EP), tensile strength (TS) and percent elongation (%E) at break values were determined for chitosan films plasticized with glycerin at two concentrations (0.25 and 0.50 mL/g chitosan). Film samples were tested after 0, 2, 4, 8 and 12 wk of storage. After an initial drop in permeability during the first 2 wk of storage, mean OP (4.6x10(-5) cc/m . day . atm) and mean EP (2.3x10(-4) cc ./m . day . atm) remained constant while mean WVP (2.2x10(-1) g/m . day . atm) decreased with respect to storage time. TS values (15-30 MPa) decreased and %E values (25%-45%) increased with respect to storage time. The stability of OP and EP values with storage was not expected, while the change in mechanical properties was as expected.