Effects of Antimicrobial Coatings and Cryogenic Freezing on Survival and Growth of Listeria innocua on Frozen Ready‐to‐Eat Shrimp during Thawing

Foodborne pathogens such as Listeria monocytogenes could pose a health risk on frozen ready‐to‐eat (RTE) shrimp as the pathogen could grow following thawing. In this study, antimicrobial‐coating treatments alone, or in combination with cryogenic freezing, were evaluated for their ability to inhibit the growth of Listeria innocua, a surrogate for L. monocytogenes, on RTE shrimp. Cooked RTE shrimp were inoculated with L. innocua at 3 population levels and treated with coating solutions consisting of chitosan, allyl isothiocyanate (AIT), or lauric arginate ester (LAE). The treated shrimp were then stored at –18 °C for 6 d before being thawed at 4, 10, or 22 °C for either 24 or 48 h. Results revealed that antimicrobial coatings achieved approximately 5.5 to 1 log CFU/g reduction of L. innocua on RTE shrimp after the treatments, depending on the inoculated population levels. The coating‐treated shrimp samples had significantly (P < 0.05) less L. innocua than controls at each thawing temperature and time. Cryogenic freezing in combination with coating treatments did not achieve synergistic effects against L. innocua. Antimicrobial coatings can help to improve product safety by reducing Listeria on RTE shrimp.     

Effect of a post-packaging pasteurization process on inactivation of a Listeria innocua surrogate in meat products

Effects of surface pasteurization on inactivation of Listeria innocua were investigated. Surface temperature, monitored during post-packaging pasteurization, was used to predict the lethality of L. monocytogenes. Temperatures reached 70°C for lean and fat sausages within 9 min of treatment. An inoculation study validated the efficacy of post-processing and the thermal lethality of L. monocytogenes. Pre-cooked sausage and ham, inoculated with approximately 10⁷ CFU/cm² of L. innocua, were heated to a surface temperature of 70°C. Numbers of L. innocua were reduced by 7 log on surface-inoculated sausage. Guidelines for safe, ready-to-eat meat products are provided for small scale meat processors.     

<Emphasis Type="Italic">Listeria</Emphasis> Inactivation by the Combination of High Hydrostatic Pressure and Lactocin AL705 on Cured-Cooked Pork Loin Slices

The effect of the bacteriocin lactocin AL705 in combination with high hydrostatic pressure (HHP) on the inactivation of Listeria innocua 7, a nonpathogenic indicator for Listeria monocytogenes, deliberately inoculated (ca. 6.4 log CFU/g) onto the surface of ready-to-eat (RTE) sliced cured-cooked pork loin, was evaluated. Nontreated pork slices (control) and treatments subjected to lactocin AL705 (105 AU/ml) and/or HHP (400 or 600 MPa) were prepared. L. innocua 7 was monitored at days 1, 20, and 40 of storage at 4 °C. The results showed a complete inhibition of L. innocua 7 after the combined treatment with lactocin AL705 and 600 MPa and no regrowing of cells up to 40-day storage. The treatment at 600 MPa alone was not enough to avoid regrowth of L. innocua. Ultrastructural cell damage was observed at the cytoplasm and cell membrane/wall levels with all treatments; however, complete cell lysis was observed only with the combined treatment. HHP in combination with lactocin AL705 provided a wider margin of safety as post-processing listericidal treatment of RTE cured-cooked meat products.     

Comparative Study on the Inactivation and Photoreactivation Response of <Emphasis Type="Italic">Listeria monocytogenes</Emphasis> Seafood Isolates and a <Emphasis Type="Italic">Listeria innocua</Emphasis> Surrogate after Pulsed Light Treatment

The inactivation and photoreactivation response of six seafood-isolated Listeria monocytogenes and one Listeria innocua strain after pulsed light (PL) treatment was evaluated. The lower inactivation levels found after exposure of treated samples to daylight during the first 90 min of storage confirmed that both L. innocua and L. monocytogenes have the capability to photorepair PL-induced DNA damage upon appropriate conditions. Photoreactivation levels from 0.2 to 2.1 log CFU cm^?2 were observed depending on treatment intensity (fluence) and Listeria strain. Complete photorepair of PL-caused damage was not found even after treatments inducing low inactivation levels. Photoreactivation increased up to 2.1 log with the applied fluence up to a threshold able to cause between 2.4 and 5.4 log reductions under dark storage. Photorepair was not avoided but lower photoreactivation was observed after higher fluence inducing more than 6 log reductions under dark storage. Both L. innocua and L. monocytogenes serotype 1/2b exhibited the highest photoreactivation levels whereas serotypes 1/2a showed the lowest ones. The overall inactivation and photoreactivation responses of tested Listeria strains were comparable indicating that L. innocua may be a good surrogate for the safe evaluation, optimization and validation of PL technology to control L. monocytogenes in food products and food processing facilities.     

Efficacy of bacteriophage LISTEXP100 combined with chemical antimicrobials in reducing Listeria monocytogenes in cooked turkey and roast beef

The aim of this study was to verify the effectiveness of the commercially available anti-Listeria phage preparation LISTEX^™P100 in reducing Listeria monocytogenes on ready-to-eat (RTE) roast beef and cooked turkey in the presence or absence of the chemical antimicrobials potassium lactate (PL) and sodium diacetate (SD). Sliced RTE meat cores at 4 and 10 °C were inoculated with cold-adapted L. monocytogenes to result in a surface contamination level of 10³ CFU/cm². LISTEX^TMP100 was applied at 10⁷ PFU/cm² and samples taken at regular time intervals during the RTE product's shelf life to enumerate viable L. monocytogenes. LISTEX^™P100 was effective during incubation at 4 °C with initial reductions of L. monocytogenes of 2.1 log₁₀ CFU/cm² and 1.7 log₁₀ CFU/cm², respectively, for cooked turkey and roast beef without chemical antimicrobials (there was no significant difference to the initial L. monocytogenes reductions in the presence of LISTEX^TMP100 for cooked turkey containing PL and roast beef containing SD-PL). In the samples containing no chemical antimicrobials, the presence of phage resulted in lower L. monocytogenes numbers, relative to the untreated control, of about 2 log CFU/cm² over a 28-day storage period at 4 °C. An initial L. monocytogenes cell reduction of 1.5 log₁₀ CFU/cm² and 1.7 log₁₀ CFU/cm², respectively, for cooked turkey and roast beef containing no chemical antimicrobials was achieved by the phage at 10 °C (abusive temperature). At this temperature, the L. monocytogenes cell numbers of samples treated with LISTEX™ P100 remained below those of the untreated control only during the first 14 days of the experiment for roast beef samples with and without antimicrobials. On day 28, the L. monocytogenes numbers on samples containing chemical antimicrobials and treated with LISTEX^TMP100 stored at 4 and 10 °C were 4.5 log₁₀ CFU/cm² and 7.5 log₁₀ CFU/cm², respectively, for cooked turkey, and 1.2 log₁₀ CFU/cm² and 7.2 log₁₀ CFU/cm², respectively, for roast beef. In both cooked turkey samples with and without chemical antimicrobials stored at 10 °C, the phage-treated samples had significantly lower numbers of L. monocytogenes when compared to the untreated controls throughout the 28-day storage period (P < 0.0001). For roast beef and cooked turkey containing chemical antimicrobials treated with LISTEX^TMP100 and stored at 4 °C, no more than a 2 log CFU/cm² increase of L. monocytogenes was observed throughout the stated shelf life of the product. This study shows that LISTEX^™P100 causes an initial reduction of L. monocytogenes numbers and can serve as an additional hurdle to enhance the safety of RTE meats when used in combination with chemical antimicrobials.     

API Listeria Rapid kit for Confirmatory Fenotypic Conventional Biochemical Test of the Prevalence Listeria Monocytogenes in Selected Meat and Meat Products

This study was conducted to confirm the prevalences Listeria monocytogenes from the conventional biochemical identification. The prevalences of pathogenic bacteria Listeria monocytogenes come from raw and processed meat products. The DIM results of confirmatory identification using the API Listeria kit showed that 4 isolates were designated as L. monocytogenes with a ‘doubtful profile’ comment, 98.69%, good identification respectively. On the other hand, 2 isolates were identified as L.innocua and L. seeligeri.     

Prevalence and characterization of Listeria monocytogenes isolated from soft cheese

A survey was made in 1995–1996 for Listeria spp. in 63 soft cheeses, made from raw ewe's milk using traditional methods, in the Province of Beira Baixa (Portugal). Listeria spp. were isolated from 47 (75%) of the cheeses, L.monocytogenes was isolated from 29 (46%), and L.innocua but not L.monocytogenes from 18 (29%). Of 24 isolates of L.monocytogenes that were serotyped, 20 were serotype 4b, three were serotype 1/2b and one was serotype 1/2a. Phage typing of isolates of L.monocytogenes and L.innocua showed that in some cases a particular phage type was associated with cheese from a particular source. Twenty four strains of L.monocytogenes tested were able to grow at 30°C in culture medium adjusted with HCl to a pH in the range from 4.4 to 6.0 within 3 days; in the pH range 4.4–6.8 a representative strain grew most rapidly at pH 6.8. The pH range in the cheeses during maturation was between about 5.2–6.4. Whether L.monocytogenes could multiply in the cheeses would depend on factors such as concentration of organic acids and of salt, and storage temperature.     

Incidence ofListeria monocytogenesand otherListeriaspecies in raw milk produced in Spain

Raw milk samples from bulk tanks of 114 farms in Central Spain were analysed forListeriatwice per season over a 1-year period.L. monocytogenesandL. innocuawere detected in 3.62 and 2.71% of 774 milk samples, respectively. No otherListeriaspecies were isolated. Most farms (85.1%) produced milk apparently free fromL.monocytogenesthroughout the 1-year sampling period. No seasonal influence on milk contamination byL. monocytogenesorL. innocuawas found.     

Simultaneous Detection of Salmonella,Listeria monocytogenes,and Staphylococcus aureus by Multiplex Real-Time PCR Assays Using High-Resolution Melting

A method combining multiplex real-time polymerase chain reaction (PCR) with high-resolution melting (HRM) analysis for rapid and specific simultaneous detection of Salmonella, Listeria monocytogenes, and Staphylococcus aureus was developed. The method included a melting-curve analysis of products and was evaluated by specificity, sensitivity and reproducibility analyses. Sensitivity and reproducibility analyses was both conducted by genomic DNA extracted from serial dilutions for each target pathogen. Assays with artificially inoculated and naturally contaminated samples after enrichment were also conducted. In the specificity test, there was no nonspecific amplification of the 44 nontarget pathogens, whereas the actual T _m values were 79.38?±?0.14, 82.54?±?0.15, and 77.36?±?0.14 °C for Salmonella, L. monocytogenes, and S. aureus, respectively. The sensitivity of the method was 3.5?×?10² CFU ml^?1 for Salmonella and L. monocytogenes and 3.5?×?10³ CFU ml^?1 for S. aureus. The coefficients of variation of T _m values ranged 0.51–1.03 % for Salmonella, 1.63–2.11 % for L. monocytogenes, and 0.75–2.17 % for S. aureus in intraassay, and ranged 0.81–2.43 % for Salmonella, 1.97–2.35 % for L. monocytogenes, and 0.93–3.93 % for S. aureus in interassay. The detection limit in artificially inoculated samples (n?=?50) was 5 CFU (25 g)^?1 food for the three tested pathogens. In the naturally contaminated samples (n?=?120),Salmonella DNA was detected by HRM, sequencing, and conventional culture-based methods at a positive rate of 25.00, 25.00, and 24.17 %, respectively; the corresponding rates for L. monocytogenes were 14.17, 14.17, and 14.17 %, respectively, while those for S. aureus were 16.7, 16.7, and 16.7 %, respectively.     

Design and Characterization of Corn Starch Edible Films Including Beeswax and Natural Antimicrobials

The effectiveness of edible films (EFs) used as coatings to maintain the quality and safety of fresh produce for long time depends on their functional properties characterization. This study was aimed to design and evaluate physicochemical, barrier, mechanical, and antimicrobial properties of EFs based on corn starch (acetylated cross-linked (ACLS) or oxidized (OS)), micro-emulsified beeswax (BW, 0–1 % w/w), and two natural antimicrobials (lauric arginate (LAE, 400–4000 mg/L) and natamycin (NAT, 80–800 mg/L)). EFs based on ACLS or OS made with 1 % BW microemulsion produced homogeneous EFs surface and did not show changes in thickness or opacity. Water vapor permeability (WVP, 0.57 ± 0.04 g mm m^?2 h^?1 kPa^?1 for ACLS, and 0.56 ± 0.05 g mm m^?2 h^?1 kPa^?1 for OS) was reduced; tensile strength (TS, 51.48 ± 5.92 MPa for ACLS, and 40.96 ± 4.98 MPa for OS), and elastic modulus (EM, 211.30 ± 7.85 MPa for ACLS, and 203.50 ± 5.35 MPa for OS) were decreased, whereas elongation at break (E, 4.59 ± 1.11 % for ACLS, and 4.76 ± 4.98 % for OS) increased. The additive effect showed by the combination of natural antimicrobials (2000 mg/L of LAE plus 400 mg/L of NAT) incorporated into EFs with 1 % BW completely inhibited Rhizopus stolonifer, Colletotrichum gloeosporioides, Botrytis cinerea, and Salmonella Saintpaul. These properties of corn starch EFs used as coatings represent an excellent alternative to extend the shelf life of fresh produce.     

Fate of Listeria on various food contact and noncontact surfaces when treated with bacteriophage

Study objective was to determine efficacy of a bacteriophage suspension against Listeria spp. when applied to three common types of materials used in food manufacturing facilities. Materials included two food contact materials (stainless steel and polyurethane thermoplastic belting) and one noncontact material (epoxy flooring). Coupons of each material were inoculated with a cocktail containing L. monocytogenes and L. innocua (4 to 5-log₁₀ CFU/cm²). Two phage concentrations and a control, 0, 2 × 10⁷ and 1 × 10⁸ PFU/cm² were evaluated. Treated samples were held at 4 or 20°C for 1 and 3 hr to determine the effect of temperature and treatment time. Reductions in Listeria populations ranged from 1.27 to 3.33 log₁₀ CFU/cm² on stainless steel, from 1.17 to 2.76 log₁₀ CFU/cm² on polyurethane thermoplastic belting, and from 1.19 to 1.76 log₁₀ CFU/cm² on epoxy resin flooring. Higher phage concentration (1 × 10⁸ PFU/cm²), longer treatment time (3 hr), and processing area temperature of 20°C showed a greater (p ≤ .05) reduction of Listeria on the stainless-steel and polyurethane thermoplastic belting coupons. Overall, Listeria reduction by phage treatment occurred on all three materials tested, under all conditions.     

Growth of Listeria monocytogenes on a RTE-meat matrix enhances cell invasiveness to mouse J774A.1 macrophages

It remains unclear whether the growth of Listeria monocytogenes on a ready-to-eat (RTE) meat matrix has an impact on the bacterium's pathogenic abilities. In this study, we investigated the impact of environments on virulence by growing L. monocytogenes (F2365 strain) on brain heart infusion agar (BHI), tryptic soy agar (TSA), and RTE turkey meat matrices. Bacteria cultured from these media were harvested and used to infect mouse macrophage cell line J774A.1 with different MOIs to examine their invasion ability. At MOI = 10 and 50, the numbers of bacteria recovered from cells infected with turkey-meat-grown Listeria were significantly higher than those from the two nutrient-rich growth media. Additionally, MOI played a role in determining L. monocytogenes recovery rates, since significant differences were found amongst all three groups at low MOI, while no significant differences were found between BHI and TSA groups at high MOI. These results indicate that environmental changes affect the ability of L. monocytogenes to invade and survive intracellularly while grown on RTE-meat matrix.     

Effects of curing additives on the control ofListeria monocytogenesby lactocin 705 in meat slurry

Meat slurry inoculated withListeria monocytogenes(4.00 cfu g⁻¹) was mixed with different levels of curing additives and their influence on the inhibitory effect of lactocin 705 (17,000 AU ml⁻¹) was evaluated at 20°C. Inhibition ofL. monocytogeneswas 1.90 and 1.00 log less in meat slurry with 5 and 7% NaCl than in meat slurry without added sodium chloride. When nitrite and bacteriocin were added together, less nitrite (200 μg g⁻¹) was required to obtain the sameListeriapopulation (3.00 log cfu g⁻¹) as when 800 μg g⁻¹NaNO₂was used. However, when compared with lactocin 705 alone, lessListeriainhibition was observed showing also a protective effect of NaNO₂. When ascorbic acid and alginate meat binder were assayed in the presence of the bacteriocin, the inhibition ofL. monocytogeneswas less effective, but when sodium lactate (2%) was added to the meat slurry, almost no protective effect was observed. These results indicated that the use of lactocin 705 to controlL. monocytogeneswas less effective in the presence of curing ingredients.     

The probiotic,Leuconostoc mesenteroides,inhibits Listeria monocytogenes biofilm formation

Listeria monocytogenes biofilm formation renders these cells highly resistant to current sanitation methods, and probiotics may be a promising approach to the efficient inhibition of Listeria biofilms. In the present study, three Leuconostoc mesenteroides strains of lactic acid bacteria isolated from kimchi were shown to be effective probiotics for inhibiting Listeria biofilm formation. Biofilms of two L. monocytogenes serotypes, 1/2a (ATCC15313) and 4b (ATCC19115), in dual-species culture with each probiotic strain were decreased by more than 40-fold as compared with single-species Listeria biofilms; for instance, a reduction from 5.4 × 10⁶ colony forming units (CFU)/cm² L. monocytogenes ATCC19115 in single-species biofilms to 1.1 × 10⁵ CFU/cm² in dual-species biofilms. Most likely, one of the Leuconostoc strains, L. mesenteroides W51, led to the highest Listeria biofilm inhibition without affecting the growth of L. monocytogenes. The cell-free supernatant from the L. mesenteroides W51 culture containing large protein molecules (>30 kDa) also inhibited Listeria biofilms. These data indicate that Leuconostoc probiotics can be used to repress L. monocytogenes biofilm contamination on surfaces at food processing facilities.     

Inactivation of Listeria monocytogenes in Skim Milk and Liquid Egg White by Antimicrobial Bottle Coating with Polylactic Acid and Nisin

ABSTRACT: This study was to develop an antimicrobial bottle coating method to reduce the risk of outbreaks of human listeriosis caused by contaminated liquid foods. Liquid egg white and skim milk were inoculated with Listeria monocytogenes Scott A and stored in glass jars that were coated with a mixture of polylactic acid (PLA) polymer and nisin. The efficacy of PLA per nisin coating in inactivating L. monocytogenes was investigated at 10 and 4 °C. The pathogen grew well in skim milk without PLA/nisin coating treatments, reaching 8 log CFU/mL after 10 d and then remained constant up to 42 d at 10 °C. The growth of Listeria at 4 °C was slower than that at 10 °C, taking 21 d to obtain 8 log CFU/mL. At both storage temperatures, the PLA coating with 250 mg nisin completely inactivated the cells of L. monocytogenes after 3 d and throughout the 42-d storage period. In liquid egg white, Listeria cells in control and PLA coating without nisin samples declined 1 log CFU/mL during the first 6 d at 10 °C and during 28 d at 4 °C, and then increased to 8 or 5.5 log CFU/mL. The treatment of PLA coating with 250 mg nisin rapidly reduced the cell numbers of Listeria in liquid egg white to undetectable levels after 1 d, then remained undetectable throughout the 48 d storage period at 10 °C and the 70 d storage period at 4 °C. These data suggested that the PLA/nisin coating treatments effectively inactivated the cells of L. monocytogenes in liquid egg white and skim milk samples at both 10 and 4 °C. This study demonstrated the commercial potential of applying the antimicrobial bottle coating method to milk, liquid eggs, and possibly other fluid products.     

Incidence of Listeria in Egyptian meat and dairy samples

A total of 180 food samples including meat (raw lean beef, frozen lean beef, and frozen chicken) and dairy products (raw milk, Zabady and Kareesh cheese) were analysed for Listeria. Isolates were differentiated using morphological, cultural, and biochemical tests and an API-Listeria kit. Zabady cheese was completely free of Listeria. The highest incidence rate (13.33%) was in frozen lean beef. Raw lean beef and milk products showed an incidence rate of 6.67%. The lowest incidence rate (3.33%) was in Kareesh cheese and frozen chicken meat samples. L. monocytogenes showed the lowest incidence rate (0.55%), isolated from one frozen lean beef sample. L. ivanovii and L. grayi showed the highest incidence rate (2.22%), isolated from 4 samples. L. innocua and L. seeligeri were positive in 3 samples (1.67%), and L. welshimeri in 2 samples (1.11%). L. monocytogenes and L. ivanovii were positive for virulence factors (hemolytic properties, and extracellular enzyme activities).     

Prevalence and antibiotic resistance of Listeria species in meat products in Ankara,Turkey

In this study, a total of 146 raw (minced, chicken, beef) and cooked (red meat, chicken) meat samples were analysed for the presence of Listeria spp. The isolates were characterized by morphological, cultural, biochemical tests according to Bergey's manual and confirmed by API-Listeria kit. Out of a total of 146 meat samples, 79 (54.10%) were found to be contaminated with Listeria spp., with the highest incidence (86.4%) occurring in raw minced meat. Listeria monocytogenes was isolated from 9 (6.16%) of the 79 samples examined. Other species isolated included L. innocua 68 (46.57%), L. welshimeri one (0.68%) and L. murrayi one (0.68%). Of the Listeria species, L. innocua (46.57%) was the most predominantly isolated species in a variety of meat samples. Overall, the Listeria strains isolated from meat and meat products were mostly resistant to cephalothin and nalidixic acid but exhibited a high degree of susceptibility to kanamycin, chloramphenicol and tetracycline. The importance of finding antibiotic resistant Listeria spp. in food is discussed.     

Impact of voltage and pulse delivery mode on the efficacy of pulsed light for the inactivation of Listeria

Listeria innocua inactivation by pulsed light (PL) was evaluated at different settings and voltages, to establish the best treatment conditions and post-treatment handling for further implementation of PL in the food industry. Fluences up to 0.2 J/cm² were applied to superficially inoculated TSA agar plates (4.5–5 log cfu/cm²). Inactivation was calculated, and log-linear and Weibull models were applied. A fluence of 0.2 J/cm² applied in a single pulse inactivated 3.8 log cfu/cm², while sequential application of this fluence yielded an inactivation between 1.5 and 2.5 log cfu/cm² depending on the delivery mode (consecutive flashing or with 5 min-holding times under ambient light or in the dark). Data from consecutive PL treatment were fitted with the Weibull model. No photoreactivation following PL was observed after 120-min exposure to ambient light in any of the conditions assayed. This study showed that flashing with a single pulse at higher voltage would offer the highest inactivation of Listeria.Industrial relevanceThis study offered information of practical interest to establish pulsed light processing and post-processing conditions for the control of Listeria spp. in the food industry, for instance in ready-to-eat (RTE) products. The use of higher voltages provided higher inactivation and allowed to minimise the number of flashes. If sequential treatments are to be applied, the treatment is more effective if short holding times are kept between pulses. The post-processing illumination conditions do not influence the efficacy of PL treatment.     

Microbiological Decontamination of Poultry Feed—Evaluation of Steam Conditioners

The microbial decontamination of chicken feed, obtained from a commercial pellet mill, was evaluated using a direct-fired steam conditioner (DFSC; APC System^™). The standard plate count of the feeds before (mash) and after (pellets) conditioning ranged from 65×10⁴ to 83×10⁵ colony forming units (CFU) g⁻¹ and from 91×10¹ to 92×10³ CFU g⁻¹, respectively. The incidence of Escherichia coli , Salmonella and Listeria in the feeds before conditioning was 61·7, 8·3 and 27·1%, respectively. Following conditioning these levels were reduced to 1·7, 1·7 and 0%, respectively. Species of Listeria and Salmonella identified included L monocytogenes , L innocua and S agona , S ohio , S heidelberg , S senftenberg , S tallahasse and S braenderup , respectively. Compared with a conventional, indirect-fired boiler-generated-steam conditioner (IFSC) the direct-fired steam conditioner proved superior in regards to pathogen decontamination; no E coli , Salmonella or Listeria were recovered from mash lots positive for these microorganisms. However, with the IFSC system, both E coli and L monocytogens were recovered at levels of 11·1 and 5·6%, respectively.     

Control of Listeria monocytogenes in whole milk using antimicrobials applied individually and in combination

Dairy product recalls and dairy-related illnesses are often the result of contamination with Listeria monocytogenes, which can occur throughout the dairy production and supply chains. The use of antimicrobial compounds is one practical approach for controlling pathogen survival and growth in foods. The goal of this study was to use fluid milk as a model system to identify listeristatic or listericidal treatments that show promise for application in fluid milk and for further evaluation in other dairy products (e.g., cheese). Caprylic acid (CA), ε-polylysine (EPL), hydrogen peroxide, lauric arginate (LAE), and sodium caprylate (SC) were added individually or in combination to whole milk inoculated with L. monocytogenes at ?4 log₁₀ cfu/mL. Samples were stored at 7°C for 21 d, and L. monocytogenes counts were determined weekly. Inhibitory concentrations of LAE (800 mg/L) and EPL (100–400 mg/L), as well as SC and CA (3,200 mg/L each), were identified. The addition of EPL at 800 mg/L reduced L. monocytogenes counts by >3 log₁₀ cfu/mL from initial inoculation levels after 21 d. Addition of hydrogen peroxide to milk reduced counts by >3 log₁₀ cfu/mL from initial inoculation within 24 h (400 and 800 mg/L) or by d 7 (200 mg/L). Although the combinatory treatments of EPL + CA, EPL + LAE, and LAE + SC were characterized as indifferent, EPL + SC worked synergistically to reduce L. monocytogenes populations in milk over 21 d. Overall, these data identify potential antimicrobial treatments to control L. monocytogenes in milk and serve as a foundation for the continued development of antimicrobial controls for L. monocytogenes in dairy products.