Efficacy of Antimicrobial Lauric Arginate against Listeria monocytogenes on Stainless Steel Coupons

Abstract

Commercially processed foods become contaminated with Listeria monocytogenes in\rpost-processing environments where favorable conditions help the bacteria\rthrive. The US Food and Drug Administration has approved Lauric arginate\r(LAE) as generally recognized as safe (GRAS) for certain food applications.\rThis study evaluated the efficacy of Mirenat-N (LAE dissolved in food-grade\rpropylene glycol) against L.\rmonocytogenes on food contact surfaces. A three-strain cocktail of L. monocytogenes was used to inoculate\r24 polished stainless steel coupons with three treatments, 100 ppm and\r200 ppm solutions of LAE and water (control); two sub-treatments of high (6 log\rCFU/ml) and low (4 log CFU/ml) inoculum levels; and two contact times of 5 and\r15 min. Attached bacteria were dislodged by vortexing coupons for 1 min with 20 g of 3-mm solid glass beads in 10 ml of\r0.1% peptone diluent, and bacterial populations were calculated by plating onto\rmodified oxford medium (MOX) and thin agar layer MOX (TALMOX). The 100 ppm\rtreatment showed average reductions of 1.38 and 2.57 log CFU/coupon at the low\rinoculum level and 0.37 and 0.62 log CFU/coupon\rat high inoculum levels, after 5 and 15 min exposure, respectively. For 200 ppm\rat the high inoculum level, 1.23 and 1.88 log CFU/coupon reductions were\rseen for 5 and 15 min, respectively; the low inoculum level at 5 and 15 min\rexposure showed reductions of ≤1.5 log CFU/coupon. The 100 ppm LAE\rtreatment was more effective at low inoculum levels for 5 and 15 min contact times\rand may be used to control low levels of contamination of L. monocytogenes on food contact surfaces.