Physico‐Mechanical Properties of Starch‐Based Films Containing Naturally Derived Antimicrobial Agents

Abstract

Thermoplastic starch (TPS) films containing relatively low [0.75 ± 0.08% (w/w)], intermediate [1.08 ± 0.04% (w/w)] and high [3.20 ± 0.29% (w/w)] levels of the antimicrobial (AM) agents carvacrol, linalool and thymol were prepared, and their physico‐mechanical and optical properties were evaluated. Addition of these AM agents to TPS film reduced the tensile strength with increasing AM agent content, with a significant effect observed at the highest AM agent concentration. The Young's modulus and elongation at break increased with increasing AM agent concentration, especially at the highest formulation concentration of AM agent. Films having a low or intermediate formulation concentration of AM agent exhibited no significant effect on their water vapour permeability, transparency and thermal properties when compared to the control film. Although scanning electron microscope imaging suggested a significant and progressive change in the surface morphologies of the films with AM agent concentration, the overall effects on the tested properties were not significant. This suggests that the direct incorporation of AM agents into TPS films did not adversely affect the films, particularly at lower AM agent concentrations. Copyright © 2013 John Wiley & Sons, Ltd.