Abstract:
The global demand for eco-friendly food packaging solutions is on the rise. Bioplastics
from natural resources have been explored widely as sustainable food packaging with an
increasing focus towards seaweed-based bioplastics. Polymer characterization is an
important aspect to enhance the performance of bioplastics. Therefore, the aims of the
present study were, to characterize Kappaphycus alvarezii seaweed-based bioplastics
plasticized with glycerol (three different concentrations), to determine the functional
properties and to evaluate the applicability of the synthesized bioplastic for food
packaging. Material characterizations were performed using FTIR-ATR spectroscopy,
XRD, TGA, UV-Vis spectrophotometry, colorimetry and tensile testing. Water vapor
permeability (WVP) was determined using the wet cup method at 33%, 75% and 84%
relative humidity (RH) conditions. Water solubility was evaluated using the method
described by Fakhoury et al. Applicability of the developed bioplastic films and the
coating solution was investigated on selected fresh fruits. Fresh-cut watermelon pieces
were wrapped with films and L*, a*, b* values, TSS and visual aspects at ambient
conditions were monitored for three days. Bananas (variety: Cavendish) with a ripening
index of 5 were coated with film forming solutions and weigh loss %, firmness, TSS and
peel browning were monitored for six days. FTIR spectra revealed the presence of
chlorophyll a, carotenoids, phaeophytin; C-C 3,6-anhydrogalactose, and D-galactose-4-
sulfate; C-O 3,6-anhydrogalactose, and D-galactose-4-sulfate; C-O, C=O and C-C
stretching of pyranose ring; S=O bond of the sulfate ester groups; -CH3 stretching and -
OH stretching vibration. X-ray diffractograms revealed the amorphous nature of the
polymer matrix. All three types of bioplastics exhibited a type 04 TGA curve indicating
the multiple stage decomposition of polymer. The bioplastic films showed acceptable
transparency and whiteness index. WVP of the films was found to be affected by the
glycerol content and the RH. Tensile stress showed a decreasing pattern with increasing
glycerol content. Water solubility ranged from 50.23% to 66.78% when increasing
glycerol concentration from 10% to 20%. The 10% glycerol added film was identified as
the most effective film type except for the transparency. Case hardening was observed in
unwrapped watermelon within one day of storage and there was a significant effect
(P<0.05) on flesh color after wrapping by the film. 20% glycerol added coating solution
was identified as the most effective in decreasing the surface moisture removal and
reduction of peel browning of bananas.
