The gelatin–Ch film forming solutions were prepared by mixing a 6%, 4% and 2% fish-skin gelatin solution with a 1.5% solution of Ch, in a proportion of 1:1 (v/v), to obtain a film-forming solution with different proportions, respectively (solutions 80G:20Ch, 70G:30Ch and 60G:40Ch). All mixtures were warmed and stirred at 45 _C for 30 min to obtain a good blend. Glycerol (0.3 g/g gelatin or Ch or gelatin plus Ch) was added as a plasticiser and solutions were again warmed and stirred at 45 _C for 15 min. The filmogenic solutions were degassed under vacuum for 15 min to remove air bubbles. Then, aliquots of 50 g of film-forming solutions were poured in polystyrene petri dishes (14 cm of diameter) and dried at ambient temperature (23–25 _C) for 72 h to yield a uniform thickness of 90 lm ฑ 12 in all cases except the 0G:100Ch formulations, which was 80 lm ฑ 7 thick. Thickness of films was determined using a micrometer (Mitutoyo Manufacturing Co. Ltd., Tokyo, Japan) to the nearest 0.001 mm at 9 random positions around the film, and average values were used in calculations. Films were conditioned at 25 _C and a relative humidity (RH) of 50 ฑ 4% RH for 48 h for further analysis.