Summary
Abstract
All food processing surfaces are potential sites for biofilm formation of foodborne pathogens, which may result in increased virulence and better adaptation to survival in foods. This study was aimed to evaluate the effect of two antimicrobials, neutral electrolyzed water (NEW) and nisin, and their combination, on Listeria monocytogenes Scott A biofilms formed on glass and stainless steel surfaces. We also examined the effects of sub-lethal doses of NEW on listeriolysin O (LLO) activity from free and biofilm listerial cells. Coupons inoculated with L. monocytogenes cells were used to produce biofilms by incubation for four days at 37 C. An orthogonal experimental design with two replicates was used to test the effect of four factors on biofilm population. The factors were antimicrobial agents: NEW (65 ppm), nisin (6976 IU/per coupon), and their combination; temperature: 20 C and 37 C; contact time: 5, 10, 20 and 45 min; and type of material: glass or stainless steel. Antimicrobial compounds and exposure time significantly affected L. monocytogenes populations in biofilms from both surfaces. A bactericidal effect was shown by NEW on free listerial cells at 30 ppm for 0.5 min of exposure, regardless treatment temperature. Same effect was observed on listerial biofilms at 65 ppm or higher concentrations, after 10 min contact time. A sub-lethal concentration of NEW acting on listerial biofilms resulted in an increased LLO activity, while non-treated biofilms exhibited a reduced activity, but higher than that found for free cells. The use of NEW as a sanitizer may be effective in reducing bacterial contamination. In addition because of its safety, which would benefit the food industry and its environmental friendliness, NEW may be of significant use in the food industry.
Study details
- Published in: Food Control 24.1 (2012): 116-122
- Microbes studied: Listeria monocytogenes
Source
Source: Food Control 24.1 (2012): 116-122
Conditions tested
| Parameter | Value |
|---|---|
| Organisms | Listeria monocytogenes |
| Relevant sectors | Contact surfaces, Food Processing, Food safety |
| Publication | Food Control, 2012 |
Reading this responsibly
Published figures are obtained under controlled conditions, usually on clean surfaces or in defined matrices. Organic load, surface condition, temperature and application coverage all affect real-world performance. Use these numbers to design a protocol, then validate it on your own site with environmental swabbing.
Applying it
Concentrations in this range are within the adjustable output of every EcoloxTech commercial system, so implementing this protocol is a settings question rather than a procurement one. Where the claim needs to sit on a registered label, see HOCl-AS200, EPA Reg. No. 101112-1.