UV barrier or transparency properties of the filmswere evaluated by
measuring the transmittance of the films at 280 and 660 nm, and their
results were also shown in Table 1.
As observed by the naked eye, the
neat carrageenan filmwas highly transparent, and showed high transmittance
values at both visible and UV ranges (91 and 74.7%, respectively).
Both transmittance values of the films decreased significantly (p< 0.05)
after the formation of nanocomposite with clay mineral and AgNPs,
however, the degree of decrease in transmittance was dependent on
the type of nanofillers. Compared with the neat carrageenan film, the
transmittance of visible (T660 nm) and UV (T280 nm) light of the clay
mineral included composite film decreased by 38% and 61%, respectively,
however, those of the AgNPs included composite film decreased by 93%
and 98%, respectively. This is mainly due to the prevention of light
transmission by the nanoparticles dispersed in the polymer matrix
(Kanmani and Rhim, 2014b). The UV barrier property of packaging film
is desirable to prevent UV light driven reactions such as lipid oxidation,
discoloration, formation of off-flavor, and loss of nutrients of the packaged
food (Ramos et al., 2013).