Release of cinnamon essential oil from polysaccharide bilayer films and its use for microbial growth inhibition in chilled shrimps

Active biodegradable bilayer films based on agar and sodium alginate were developed by the incorporation of cinnamon essential oil in the upper layer. The release of both cinnamaldehyde and eugenol from the agar and alginate bilayer films into water at 4 degrees C and 20 degrees C did not increase significantly from 9 h onwards, and consequently increasing values of antioxidant activity measured by ferric reducing ability and radical scavenging capacity were observed until 9 h in both cases. Agar bilayer films showed an antimicrobial activity approximately 1.4-fold higher than the alginate bilayer films, although both of them were effective against all the microorganisms tested in this study, especially against Photobacterium phosphoreum. Both agar and alginate bilayer films allowed to reduce significantly the microbial growth, including the pathogenic bacteria Listeria monocytogenes, in peeled shrimps during the chilled storage without a negative impact on the organoleptic properties. (C) 2014 Elsevier Ltd. All rights reserved.