Solutions with various proportions of starch, glycerol, agar, and
span 80 were processed into films by casting method (Wu et al.,
2009) and the compositions of the composite films are listed in
Table 2. The homogenous and clear film forming solution was prepared
by dispersing starch and additives in distilled water and was
heated gradually up to 70
±
5 ◦C with stirring and kept for 30 min.
The dissolved air from the solution was removed by degassing
under vacuum and 20 ml of the solution was transferred to 9 cm
internal diameter Petri dishes resting on a leveled surface for casting
and then the films were dried in a controlled temperature
chamber at 25 ◦C for 48 h. The films were carefully separated from
the Petri dishes and equilibrated at 25 ◦C, 58% relative humidity for
72 h prior to further analysis.