Although the contour plots on tensile properties may suggest
some slight plasticizing effects of citric acid (decreasing strength
and modulus, and increasing elongation), those effects were not significant
by themselves (Table 2). However, it is important to consider
that the citric acid content for each run was based on pectin,
and not on total solids of the films. So, in films with higher pomegranate
juice contents, the absolute citric acid contents (in dry matter)
were obviously decreased, and so were its effects, by dilution. The
graphs in Fig. 2 were then plotted to indicate the individual effects
of citric acid (on a dry film basis instead of on a pectin basis) on tensile
properties and WVP. A noticeable and different behavior was
then observed, indicating that higher citric acid contents decreased
elongation, increased tensile strength and modulus, and decreased
WVP, suggesting a possible crosslinking effect.