Antibacterial activity of plasma-treated polypropylene membrane functionalized with living Carnobacterium divergens in cold-smoked salmon

Abstract

In recent years, bacteriocins produced by lactic acid bacteria (LAB) have shown great potential for food safety preservation, especially for ready-to-eat products. In this study, bio-protective membrane was made from plasma-treated polypropylene film and functionalized with Carnobacterium divergens V41 (bacteriocin-producing strain) for the purpose of inhibiting Listeria monocytogenes growth in culture media and cold-smoked salmon (CSS) at refrigerated temperatures. In semi solid Brain Heart Infusion (BHI) agar, bio-protective plastic membrane led to a 3-Log reduction in L. monocytogenes count compared to the control, after 14 days of aerobic incubation at 8 °C. In vacuum-packed CSS, L. monocytogenes growth was inhibited by bio-protective plastic membrane after 7 days of storage at 4 °C and 21 days at 8 °C. Antilisterial activity of plastic membrane was even better than C. divergens cells added in CSS by direct spraying. Stability test has shown that bio-protective plastic membrane stored for 42 days at 4 °C still exerted antimicrobial activity against L. monocytogenes on BHI agar (2-Log reduction compared to the control). These preliminary results demonstrate that bio-protective plastic membrane can be used to control pathogenic bacteria in food products with potential industrial development.