Investigation of the physical properties of gluten-based active film containing free and encapsulated Marjoram (Origanum majorana L.) essential oil and evaluation of its performance in the control of microbial spoilage in UF cheese and red meat

The aim of this research was to fabricate wheat gluten based active film containing free and encapsulated Marjoram essential oil (MEO). The MEO was encapsulated by lipid nanocarrier (nanoemulsion) and protein-based nanocarrier (Pickering emulsion by WPI) and used at the concentrations of 1, 3 and 5% in the formulation of gluten films. The free MEO was used at same concentrations. The physical properties of active films and also their performance in the control of microbial spoilage in the real food models including UF cheese and red meat during 9 days of storage were evaluated. The results indicated that the water vapor permeability (WVP) increasesd by increasing free MEO but the encapsulated MEO caused to significant decrease in the WVP values (p<0/05). The tensile strength, Young’s modulus and elongation to break of films decreased by adding free MEO but the encapsulated samples caused to improve the mechanical properties. Moreover, the results of the colony counting of E.coli and L. monocytogenes cultured on the surface of UF cheese and red meat wrapped with active films, indicated that for all samples, the microbial growth had increasing manner during storage and by increasing the concentration of MEO, the microbial count decreased significantly in comparison to the control sample (p<0.05). The encapsulation had no adverse effect on the antimicrobial activity of MEO. Generally, the results of this research indicated that loading of encapsulated MEO causes to improve the physical properties of active gluten film and is able to control the microbial growth in Ultra-refined cheese and meat.