Antimicrobial Properties of Ethylene Vinyl Alcohol/Epsilon-Polylysine Films and Their Application in Surimi Preservation

Abstract

10 11Polymer films based on ethylene vinyl copolymers (EVOH) containing a 29% (EVOH29) and a 12 44% molar percentage of ethylene (EVOH44), and incorporating ε-polylysine (EPL) at 0, 1, 5 13 and 10% were successfully made by casting. The optical properties and the amount of EPL 14 released from the films to phosphate buffer at pH 7.5 were evaluated, films showing great 15 transparency and thoseEVOH29 copolymer releasing a greater amount of EPL. The 16 antimicrobial properties of the resulting films were tested in vitro against different foodborne 17 microorganisms and in vivo in surimi sticks. With regard to the antimicrobial capacity tested in 18 vitro in liquid medium at 37 °C and 4 °C against Listeria monocytogenes and Escherichia coli 19 over a period of 72 h, films showed a considerable growth inhibitory effect against both 20 pathogens, more notably against L. monocytogenes, and being EVOH29 more effective than 21 EVOH44 films. At 37 ºC total growth inhibition was observed for EVOH 29 films incorporating 22 10% EPL against both microorganisms whereas the copolymer EVOH 44 did show total 23 inhibition against L. monocytogenes and the growth of E. coli was reduced by 6.64 log units. At 24 4 ºC no film was able to inhibit completely bacterial growth. Scanning electron microscopy 25 micrographs showed corrugated cell surfaces with blisters and bubbles, and collapse of the cells 26 appearing shorter and more compact after treatment with EPL. Finally, the films were 27 successfully used to increase the shelf life of surimi sticks. The results show the films developed 28 have great potential for active food packaging applications.

Inhibitor‐Assisted High‐Pressure Inactivation of Bacteria in Skim Milk

“…HHP can inactivate L. monocytogenes by causing morphological changes in its internal and external cellular structures and through cell wall rupture and membrane damage (Huang and others ). Muriel‐Galet and others () observed that ε‐PL affected the membrane via electrostatic adsorption and caused cell collapse. In this study, SEM analysis revealed the characteristics underlying the efficient inactivation of L. monocytogenes by the combined treatment.…”

Antimicrobial Activity of ε-Poly-l-lysine after Forming a Water-Insoluble Complex with an Anionic Surfactant

“…ε-PL is a naturally occurring nylon-like polymer showing antimicrobial activities, but is not a plastic-friendly polymer, because the addition of a large amount of ε-PL to plastics induced a phase separation or color change even in hydrophilic plastics. , As mentioned earlier, the PL n + /BEHS – -complex is soluble in organic solvents. This chemical property would enable the complex to be miscible in commodity hydrophobic plastics such as PP.…”

The inhibition mechanism of ϵ‐polylysine against Bacillus cereus emerging in surimi gel during refrigerated storage

“…Currently, the main directions for research on microbial control in surimi products include thermal sterilization, chemical bacteriostasis, and physical bacteriostasis . The combination of various methods such as basic amino acids coupled with microwave irradiation can also be used to achieve better antibacterial effects.…”