Biodegradable Packaging Films From Modified Barnyard Millet Starch: Influence of Ultrasound and Gamma Irradiation on Physicochemical, Functional, and Mechanical Properties

ABSTRACT In this study, ultrasonication (US) and gamma irradiation (GS) modified barnyard millet starch was employed for the development of biodegradable packaging films. The obtained films were characterized for moisture, solubility, water activity, optical properties, permeability characteristics, mechanical strength, surface morphology, thermal properties, and soil biodegradability test. The moisture, solubility, and water activity of modified starch films decrease after modification suggested a reduction in hydroxyl group in modified films and less ability to retain water, which enhances the structural and physical strength of biodegradable films. The variation in color ( L *) was observed, and transparency values were enhanced after modification. The highest transparency values (94.29%–94.68%) were observed for US‐starch modified films (UF) associated with enhanced film homogeneity. The water vapor permeability reduces after modification, and the lowest was observed in UF films, suggesting that US produces denser and uniform film structure by breaking up starch clusters and removing imperfections. Similarly, tensile strength enhances after modification, and highest was observed for UF film (1.31 MPa). SEM micrographs show modified films have a smoother and more homogeneous surface and better thermal stability than native films. The soil biodegradability test shows all films completely degrade within a span of 25–30 days, indicating their strong potential as sustainable biodegradable packaging materials.