MECHANICAL AND BARRIER PROPERTIES OF EDIBLE CHITOSAN FILMS AS AFFECTED BY COMPOSITION AND STORAGE

Oxygen permeability coefficients (OF), water vapor permeability coeffi cients (WVP), ethylene permeability coefficients (EP), tensile strengt h (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 fi rst 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 (2.2 x10(-1) g/m . day . atm) decreased with respect to storage time. TS va lues (15-30 MPa) decreased and %E values (25%-45%) increased with resp ect to storage time. The stability of OP and EP values with storage wa s not expected, while the change in mechanical properties was as expec ted.