Effects of Herba Lophatheri extract on the physicochemical properties and biological activities of the chitosan film.

Active films based on chitosan incorporated Herba Lophatheri extract (HLE) with different concentrations were developed. Physicochemical properties of the chitosan films incorporated HLE, including density, opacity, moisture content, color, water solubility, swelling, water vapor permeability and oil resistance were measured. Biological activities of the films include antioxidant activity and antimicrobial properties, which were characterized in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity and Oxford cup method, respectively. The potential interactions between chitosan and HLE in the films were investigated by Attenuated total reflectance-Fourier transform infrared analysis and X-ray diffraction. The results indicated that the moisture content, water solubility, swelling degree, water vapor permeability and oil absorption rate of chitosan/HLE films decreased up to 14.81%, 38.97%, 48.03%, 69.23% and 80% in comparison with the control chitosan film. The DPPH free radical scavenging activity of chitosan/HLE films increased by nearly 3.5 folds, and the diameter of inhibitory zone of the chitosan/HLE films extract solution against Staphylococcus aureus and Escherichia coli increased 17.02% and 19.28%, respectively. Additionally, the incorporation of HLE caused interactions between chitosan and HLE and gave rise to the chitosan/HLE films more opacity, darker, redness and yellowness appearance. In summary, the addition of HLE enhanced the moisture and oil resistance, antioxidant activity which declined with time, and antimicrobial activity of the chitosan film, which were all desirable for food packaging.
(Copyright © 2019. Published by Elsevier B.V.)