The method of preparation was adapted from V.P Cyras et al. [12] and P.C Araujo-Farro et al. [13].
Native cassava starch or native tree cassava starch (5 g/100 g total film solution) was dispersed in distilled
water with the corresponding content of glycerol (30, 35, 40 and 45 wt% on starch dry basis) at room
temperature and stirred for 1 h on a magnetic stirrer (250 rpm). The mixture was then heated to (80 ± 1) °C
in a thermal bath under constant stirring for 15 min, the heating continued for another 15 min at 80°C. Then
the films were obtained by casting, pouring the hot suspension into rectangular moulds (12.4 x 18.4 cm2
bottom area). These moulds were left at room temperature for at least 4 h to allow bubbles to dissipate and
then dried in an oven with air circulation, at 30°C for 50 h. The dry films were removed from the moulds
and stored at controlled conditions (21°C and 63% of relative humidity) for at least 48 h before
measurements.