In vitro antimicrobial effect of basil seed mucilage-chitosan films containing Ziziphora clinopodioides essential oil and MgO nanoparticles

Abstract

Objective(s): Edible films and coatings are becoming increasingly important in food preservation applications to maintain quality and extend shelf-life in perishable foods. The aim of this study was to investigate the effect of gamma irradiation at 0 and 5 KGy on in-vitro antimicrobial property of basil seed mucilage-chitosan films containing Ziziphora clinopodioides essential oil (ZEO) and MgO nanoparticles against Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, and Bacillus subtilis. Methods: The gamma irradiation doses for fabricated films were 0 and 5 kGy using a 60Co source with a dose rate of 4.18 kGy/h at the Atomic Energy Organization of Iran (Tehran, Iran). The antimicrobial property of basil seed mucilage-chitosan films were evaluated using agar disk diffusion and broth micro-dilution assays. Results: The main chemical composition of ZEO were found to be carvacrol (65.22%), thymol (19.51%), ɣ-terpinene (4.63%), and p-cymene (4.86%). The highest antimicrobial activity was found for film containing ZEO 2% + MgO nanoparticles 0.2% with inhibition zone and log DP of 5-7.9 mm and -1.76 - -3.33, respectively. S. aureus was the most sensitive bacteria for the prepared films with inhibition zone and log DP of 5.4-7.9 mm and -0.41 - -3.34, respectively. A smooth, compact, and homogeneous surface without grainy and porous structure was observed in the pure films. MgO nanoparticles and ZEO completely incorporated in the film matrices. Conclusion: According to our results, it may be recommended that basil seed mucilage-chitosan films containing ZEO and MgO nanoparticles can be used for increasing shelf-life of stored food commodities.