Preparation and investigation of Withania Somnifera extracts on physicochemical, antimicrobial, and mechanical properties of edible films based on sago starch

Abstract

Nowadays, extensive investigations have been conducted on developing novel biopolymers from biodegradable sources. In the current study, the active packaging film based on sago starchcontainingvarying concentrations (1, 1.5 and 2 MIC) of Withania SomniferaL. extract were produced. The Minimal Inhibitory Concentration (MIC) and Minimal Bactericide Concentration (MBC) of extract were measured. Physicochemical (such as thickness, water absorption capacity (WAC), water solubility (WS), water vapor permeability, Oxygen Permeability (OP) and contact angle (CA)), mechanical (tensile strength, elongation to break and modulus of elasticity) and antioxidant properties of the films were evaluated. The antibacterial activity of the films also was tested against two common food-borne pathogens (Escherichia coli, and Staphylococcus aureus) by the disc diffusion method. The results showed that increasing concentrations of Withania SomniferaL. extract have a significant effect (p <0.05) to increase the amount of thickness, WS, water vapor permeability, OP, and CA, but was not effective on WAC.Withania SomniferaL. extract increased the absorption of color in the visible region, which in turn led to an increasing of the parameters a * (index color tends toward green) and b * (index color tends towards yellow) but reduced L * .An increase in Withania SomniferaL. extract content resulted in a plasticizing effect, reducing the tensile strength and Young's modulus but a concurrent increase in elongation at break. Sago films containing higher percentagesof Withania SomniferaL. extract were effective against all two tested bacterial strains, and these effects were more significant in the case of the gram-positive bacteria. Sago film containing extractshowed a good DPPH radical scavenging activity. These results suggest that the developed sago films containingWithania SomniferaL. extract could be used in various food packaging applications.