Antimicrobial Activity of Lactoperoxidase System Incorporated into Cross-Linked Alginate Films

In this study, the antimicrobial effect of lactoperoxidase (LPS) incorporated alginate films was investigated on Escherichia coli ( NRRL B-3008), Listeria innocua ( NRRL B-33314), and Pseudomonas fluorescens ( NRRL B-253) in presence of different concentrations of H2O2 (0.2, 0.4, and 0.8 mM) and KSCN ( 1, 2, and 4 mM). The incorporation of 70 nmol ABTS/min/cm(2) LPS into alginate films gave 0.66 to 0.85 nmol ABTS/min/cm(2) enzyme activity at 0.2 to 0.8 mM H2O2 concentration range. The antimicrobial activity of LPS system on target bacteria changed according to the concentrations of KSCN and H2O2. The growth of all tested bacteria was prevented for a 6-h period by applying LPS system in presence of 0.4 or 0.8 mM H2O2 and 4 mM KSCN. At 0.8 mM H2O2 and 4 mM KSCN, the LPS system also inhibited growth of L. innocua and P. fluorescens for a 24-h incubation period, whereas E. coli growth could not be inhibited for 24 h under these conditions. At 0.2 mM H2O2 and 1 to 4 mM KSCN, a considerable inhibitory effect was obtained only on P. fluorescens. The decreasing order of the resistance of studied bacteria to LPS system is as follows: E. coli, L. innocua, and P. fluorescens. The developed antimicrobial system has a good potential for use in meat, poultry, and seafood since alginate coatings are already used in these products. Further studies are needed to test the LPS incorporated edible films in real food systems.