Functional properties of starch-chitosan blend bionanocomposite films for food packaging: the influence of amylose-amylopectin ratios

The present study is focused on the influence of amylose and amylopectin ratio on crystallinity, water barrier, mechanical, morphological and anti-fungal properties of starch-based bionanocomposite films. The different sources of starch containing various proportion of amylose and amylopectin (high amylose corn starch, 70:30; corn starch, 28:72; wheat starch, 25:75; and potato starch, 20:80) has been incorporated with chitosan (CH) and nanoclay (Na-MMT). Amylose and amylopectin ratio has regulated the orientation of molecular structure in the starch-based films. Experimental results have revealed that the prepared bionanocomposite films that of CS/CH/nanoclay has exhibited higher crystallinity and molecular miscibility among corn starch, with chitosan and nanoclay were confirmed by XRD. CS/CH/nanoclay has exhibited lowest water vapor permeability and highest tensile strength due to molecular space present in corn starch. Fourier transform infrared spectroscopy has confirmed the shift of amine peak to a higher wavenumber indicating a stronger hydrogen bond between starch and chitosan. Finally, the best bionanocomposite films were tested for food packaging applications. Low-density polyethylene has exhibited fungal growth on 5th day when packed with bread slices at 25 °C and 59% RH whereas CS/CH/nanoclay bionanocomposite film did not show the same for at least 20 days. CS/CH/nanoclay film could potentially be useful for active packaging in extending shelf life; maintaining its quality and safety of food products thus substituting synthetic plastic packaging materials.