Synergistic effect of chitooligosaccharides and lysozyme for meat preservation

The objective of this study was to enhance the antibacterial spectrum of lysozyme with the use of chitooligosaccharides (COS) produced by radiation treatment of chitosan. Exposure of chitosan solution to gamma radiation led to formation of oligosaccharides of different molecular weights. COS with molecular weight of 8.3 kDa were found to exhibit highest antioxidant potential in free radical scavenging assay but antibacterial activity decreased with decrease in molecular weight. Combination of COS and lysozyme was more effective against Gram-negative bacteria than when used alone. This clearly indicated the synergistic effect of the two antibacterial agents added together. When tested in meat model system, the combination treatment resulted in complete elimination of Escherichia coli, Pseudomonas fluorescens and Bacillus cereus and reduced the load of Staphylococcus aureus cells in packed inoculum and storage studies. The shelf life of minced meat containing COS-lysozyme mixture was extended up to 15 days at chilled temperatures. (C) 2008 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.