Unveiling the physicochemical properties of natural Citrus aurantifolia crosslinked tapioca starch/nanocellulose bionanocomposites

Abstract

Bionanocomposites from low cost and non-scarce resource tapioca starch (TS)-based film were synthesized for food packaging applications. Two types of crosslinkers, namely Citrus aurantifolia, also known as lime juice (LJ), and a commercialized citric acid (CA), were used one at a time with glycerol via solvent casting for comparison purposes. Varying amounts of nanocellulose (NC) extracted from oil palm empty fruit bunches (OPEFB) were added as the reinforcing filler via acid hydrolysis. Structural, tensile, physical properties and water vapor permeability characterizations were carried out. Crosslinking between TS and LJ through esterification were validated through the Fourier transform infrared spectroscopy, degree of substitution and degree of di-esterification results. Ten parts per hundred parts of starch (phs) of LJ enhanced the flexibility of TS bionanocomposite as its break elongation of 106% was the highest, while NC (1 phs) increased its tensile strength with the highest value of 13.5 MPa. Crosslinkers did not considerably affect the optical property of TS bionanocomposites but the addition of NC reduced its transparency. TS bionanocomposite films with both LJ and NC have lower water vapor permeability (WVP). The WVP of LJ-crosslinked TS film with 1 phs NC reduced about 55%, compared to neat TS film. This outcome showed that LJ is usable in starch crosslinking as the results obtained were comparable to those of the commercialized citric acid. The developed LJ-crosslinked TS bionanocomposites with enhanced tensile properties and water resistance could be used as food packaging, especially for dry food.