Study on the effect of Ziziphora clinopodioides essential oil and methanolic pomegranate peel extract on physical, mechanical and antibacterial properties of edible chitosan film

In the recent years, numerous studies have been focused on the production and applying of biodegradable polymers due to concern regarding the environmental pollution caused by plastic packaging materials, and also increasing consumer’s interest for improvement of quality and appearance of food products. Therefore, the aim of the present study was to evaluate the effects of methanolic pomegranate peel extract (PPE) separately and in combination with Ziziphora clinopodioides essential oil (ZEO) on the physical, mechanical and antibacterial properties of chitosan film. The analysis of the chemical composition of Z. clinopodioides essential oil was conducted by means of gas chromatography with mass spectrometry (GC-MS). Physical and mechanical properties of the investigated films including thickness, tensile strength, elongation at break, water vapour permeability (WVP) and color were examined. Antibacterial property of the films was evaluated against Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli O157:H7 using disk diffusion method. According to the results of the present study, the best antibacterial property (inhibition zone between 5.5-6.1 mm), highest tensile strength (59.6 MPa), thickness (0.081 mm) and elongation at break (41.6%), lowest WVP (21.3 g mm/kPa h m2) and also lowest lightness (L*= 45.41) were observed for chitosan film incorporated with ZEO 1% PPE 1%. The chitosan film incorporated with ZEO and PPE have shown good antibacterial, physical and mechanical properties which can be barrier against bacterial and chemical contamination in food products.