THERE IS INCREASING INTEREST IN EDIBLE FILMS AND COATINGS

The effects of acid (acetic, formic, lactic, propionic) concen-trations, plasticizer concentrations, and storage time (up to 9 wk) on mechanical properties, water vapor permeability, and oxygen permeability of solution-cast chitosan films were determined. Measured water vapor permeability coefficients ranged from 5.35 to 13.20 3 10-1g/m·day·atm. Oxygen per-meated coefficients ranged from 0.08 to 31.67 3 10-3 cc O2/ m·day·atm. Neither property was affected by storage time. Tensile strength (6.85–31.88 Mpa) also was not time depen-dent, but elongation (14–70%) decreased with storage time. Lactic acid solutions produced the lowest oxygen perme-ability values, formic acid the highest. Films formed with 7.5% lactic acid solutions had uniquely high values for elonga-tion at break