Physicochemical properties of biodegradable edible films developed from sago starch: effects of phycocyanin, nano-ZnO, and a combination of experiments and theory.

Sago starch films with incorporation of phycocyanin (PC) (0.2, 0.4, 0.6, 0.8, and 1.0 %, w/w) and phycocyanin (1.0 %) with zinc oxide nanoparticles (ZNP) (0.01 %, v/w) were investigated in this study. Their physicochemical properties were characterized using UV-Visible, x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) spectra, and thermogravimetric analysis (TGA). The thickness of the films increased from 0.13 to 0.15 mm when films incorporated PC and PC ZNPs. Incorporation of PC into the sago starch matrix decreased tensile strength (0.67), increased elongation at break (44.72), increased moisture content (16.54), and increased water solubility (33.39). Incorporation of PC ZNPs increased TS (2.18 MPa) and decreased EAB (24.90 %), reduced moisture content (12.80 %), and decreased water solubility (24.45 %). The findings also showed that adding PC enhanced the film's thermal stability. The Gaussian 09 program was used to optimize the structure of each studied compound at the wb97xd/6-311G(d) level of the density functional theory (DFT), FTIR, XRD, and TGA confirmed the interactions between phycocyanin and Sago. Sago starch films incorporated with PC and PCZNPs show potential application for active packaging in food industries.