Tensile strength, elongation, Young’s modulus, puncture force,
and puncture deformation are the most commonly reported
responses to describe the mechanical properties of the edible films.
According to the ANOVA (Table 5), tensile strength was influenced
by the effects of glycerol concentration (X2), agar content (X3), span
80 concentrations (X4), and by interactions of the starch content
with glycerol concentration (X12), glycerol concentration with agar
content (X23), and with span 80 concentrations (X24). The quadratic
effects of all the variables influence the tensile strength of the
starch based films. The results showed (Fig. 3a) that higher content
of starch combined with agar induced the formation of films
with higher tensile strength. This is attributable to the formation
of inter-molecular hydrogen bonds between starch and agar and
also the compact structure of the films and it enhanced the tensile
strength directly. The interaction between the glycerol and span 80
(Fig. 3b) decreases the tensile strength at higher concentrations and
it is mainly due to more molecular mobility between the polysaccharide
chains and thus enhancing the initial plastic effect. Due
to the plasticizing effect, the free volume between the adjacent