An investigation of the role of fabrication process in the physicochemical properties of κ-carrageenan-based films incorporated with Zataria multiflora extract and nanoclay

In the present research, biodegradable κ- carrageenan (KC) nanocomposite film was prepared by incorporation nanoclay, 1–3% v/v of Zataria multiflora plant extract (ZME) and glycerol as a plasticizer via two different procedures. The nanocomposite films were characterized by their optical, microstructural, mechanical and thermal as well as antimicrobial properties against S. aureus, B.cereus, E.coli, and P. aeruginosa. The films fabricated by both procedures showed excellent UV protection with smooth surfaces with compact structural integrity. Furthermore, it was found that the step of plasticizer addition directly affects the mechanical properties of the final nanocomposite film. Particularly, the addition of glycerol before the nanoclay to carrageenan solution could enhance the tensile strength about 56 % while it resulted in 61 % lower elongation at break in the sample containing 3 % ZME, compared to the samples that were prepared by addition of glycerol after nanoclay. The antimicrobial properties of all nanocomposites presented good inhibitory against E. coli and P. aeruginosa. Generally, the addition of glycerol at the beginning of film-forming solution improved the UV barrier, microstructural, mechanical, thermal and antibacterial properties of the KC nanocomposite. The results suggest that the developed KC/ZME/nanoclay nanocomposite could be used as alternative active packaging in the food industry.