Antimicrobial food packaging film based on the release of LAE from EVOH.
The aim of this work was to develop antimicrobial films for active packaging applications containing the natural antimicrobial compound LAE (lauramide arginine ethyl ester) in EVOH copolymers with different mol % ethylene contents (i.e. EVOH-29 and EVOH-44). EVOH-29 and EVOH-44 films were made by casting and incorporating 0.25%, 1%, 5%, and 10% LAE in the film forming solution (w/w with respect to polymer weight). Previously, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of LAE against Listeria monocytogenes, Escherichia coli, and Salmonella enterica were determined by a microdilution assay. The antimicrobial activity of the resulting films was tested in vitro against these microorganisms in liquid culture media. The activity of the films was also evaluated over time. The results showed that films containing 5% and 10% LAE produced total growth inhibition and viable counts decreased with 0.25% and 1% LAE. Finally, the effectiveness of the films was tested by applying them to an infant formula milk inoculated with L. monocytogenes and S. enterica and stored for 6 days at 4°C. The application of films with LAE to infant formula milk inoculated with L. monocytogenes reduced at the end of storage period about 4 log in case of 10% LAE and with S. enterica reduced 3.74 log and 3.95 log with EVOH 29 5% and 10%, respectively, and EVOH-44 5% and 10% LAE reduced 1 log and 3.27 log, respectively, at the end of storage. The antimicrobial capacity of EVOH-29 films was greater than that of EVOH-44 films in all the cases tested. In general, the films were more effective in inhibiting the growth of L. monocytogenes than S. enterica, this inhibition being more acute at the end of the storage time.
Instituto de Agroquímica y Tecnología de los Alimentos, CSIC, Paterna, Valencia, Spain.
Virginia
V
Muriel-Galet
Gracia
G
López-Carballo
Rafael
R
Gavara
Pilar
P
Hernández-Muñoz
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology; D001120:Arginine / Q000031:analogs & derivatives / Q000737:chemistry; D015169:Colony Count, Microbial; D005516:Food Microbiology; D018857:Food Packaging / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007223:Infant; D041943:Infant Formula; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development*; D008826:Microbial Sensitivity Tests; D011145:Polyvinyls / Q000737:chemistry; D019779:Salmonella enterica / Q000187:drug effects / Q000254:growth & development*
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D011145:Polyvinyls; C020320:ethylene-vinyl alcohol copolymer; C031371:N(alpha)-lauroylarginine ethyl ester; D001120:Arginine