Effect of Filling Type and Heating Method on Prevalence of Listeria species and Listeria monocytogenes in Dumplings Produced in Poland

The count of Listeria monocytogenes was determined, before and after heat treatment, in 200 samples of dumplings of 9 brands and with different types of stuffing. Analyses were conducted according to ISO 11290–1 standard and with real‐time PCR method. The highest count of L. monocytogenes was found in meat dumplings (10² to 10⁴ CFU/g), whereas products with white cheese‐potato stuffing and vegetable‐mushroom stuffing contained significantly less Listeria, 20 to 80 and 5 to 32 CFU/g, respectively. In cooled meat dumplings the extent of contamination depended significantly on the producer. In addition, a significant (P < 0.05) correlation was determined between contamination level and meat content in the stuffing (rho = 0.418), especially in stuffing containing pork meat (0.464), contrary to beef‐containing stuffing (0.284). Heating dumplings in boiling water for 2 min completely eliminated L. monocytogenes in meat dumplings. In contrast, the microwave heating applied for 2 min at 600 W only reduced the count of L. monocytogenes by 1 to 2 logs. Hence, the microwave heating failed to reduce the risk of infection with this pathogen below the level permissible in the EU regulation, especially in the most contaminated samples. In this case, the efficacy of microwave heating was significantly (P < 0.05) affected by the initial count of L. monocytogenes (rho = 0.626), then by meat content in the stuffing (0.476), and to the lowest extent—by the type of meat (0.415 to 0.425). However, no Listeria sp. and L. monocytogenes were isolated from cooked dumplings with fruits (strawberries or blueberries).     

Effect of Salt Reduction on Growth of Listeria monocytogenes in Meat and Poultry Systems

Abstract: Reducing sodium in food could have an effect on food safety. The objective was to determine differences in growth of Listeria monocytogenes in meat and poultry systems with salt substitutes. For phase 1, fresh ground beef, pork, and turkey with NaCl, KCl, CaCl₂, MgCl₂, sea salt, or replacement salt added at 2.0% were inoculated with L. monocytogenes to determine growth/survival during 5 d at 4 °C to simulate a pre‐blend process. L. monocytogenes populations significantly decreased (0.41 log CFU/g) during the storage time in beef, but no differences (P > 0.05) were observed over time in pork or turkey. Salt type did not affect (P > 0.05) L. monocytogenes populations during pre‐blend storage. MgCl₂ and NaCl allowed significant growth of aerobic populations during storage. For phase 2, emulsified beef and pork products were processed with 2% NaCl, KCl, sea salt, or a NaCl/KCl blend and post‐process surface‐inoculated with L. monocytogenes to determine growth/survival at 4 °C for 28 d. Pork products showed significantly greater L. monocytogenes population growth at all sampling times (0, 7, 14, 21, and 28 d) than beef products, but salt type had no effect on L. monocytogenes populations with sampling times pooled for data analysis. Although salt types had no impact on L. monocytogenes populations in preblend and emulsified meat products, pork and turkey preblends and emulsified pork had greater L. monocytogenes populations compared with beef products. These studies demonstrate that sodium may not affect the safety of preblends and emulsified meat and poultry products. Practical Application: odium reduction in food is an important topic because of sodium's unfavorable health effects. This research shows that reducing sodium in pre‐blends and emulsified meat and poultry products would have no effect on Listeria monocytogenes populations, but replacement of NaCl with MgCl₂ may affect growth of aerobic populations.     

Antilisterial effect of two bioprotective cultures in a model system of Iberian chorizo fermentation

This study reports the different effects of two bioprotective cultures on the growth of different Listeria monocytogenes strains by a rapid assay simulating the first stage of Iberian chorizo fermentation. Ground pork with or without protective cultures was inoculated with L. monocytogenes and incubated under two different conditions simulating the traditional, slow fermentation temperature (7 °C, 1 day) and a high, fast fermentation temperature (20 °C, 1 day), followed in both cases by storage at 7 °C for 13 days. Both bioprotective cultures reduced the growth of L. monocytogenes by at least 2 log CFU g^?1 at the end of both incubation periods compared with a noninoculated culture control lot. The best results were obtained with the strain Lactobacillus sakei CTC494, which exerted a bactericidal effect on L. monocytogenes under both conditions assayed, achieving a 5.4‐log reduction after 14 days compared with the control when the initial temperature was 20 °C.     

Shelf Life Determination of Sliced Portuguese Traditional Blood Sausage—Morcela de Arroz de Monchique through Microbiological Challenge and Consumer Test

Morcela de Arroz (MA) is a ready‐to‐eat blood and rice cooked sausage produced with pork, blood, rice, and seasonings, stuffed in natural casing and cooked above 90 °C/30 min. It is commercialized whole, not packed, with a restricted shelf life (1 wk/0 to 5 °C). The objective of this work was to establish sliced MA shelf life considering both the behavior of L. monocytogenes through a microbiological challenge test (MCT) and the consumer acceptability of MA stored: vacuum packed (VP), modified atmosphere packed (MAP: 80% CO₂/20% N₂), and aerobic packed (AP). The MCT was conducted inoculating ±3 log CFU/g of L. monocytogenes cell suspension on the MA slices. Packaged samples were stored at 3 ± 1 °C and 7 ± 1 °C until 20 d. At 3 ± 1 °C, L. monocytogenes behavior was not affected by packaging or storage time. At 7 ± 1 °C, the pathogen increased nearly 1 log CFU/g in the first 4 d. L. monocytogenes populations in AP were higher (P < 0.05) than in MAP. The pathogen may grow to hazardous levels in the 1st days if a temperature abuse occurs. Considering the acceptability by the consumers, the shelf life of MA stored at 3 ± 1 °C was 4.4 d for AP, 8.1 d for VP, and 10.4 d for MAP. The sensory shelf life established based on sensory spoilage is shorter than the shelf life to maintain the population of L. monocytogenes in safe levels.     

Formation and dispersal of biofilms in dairy substrates

The formation and dispersion of biofilms in the dairy industry is a problem because it increases cross‐contamination, affecting the shelf life of the products and their safety. The objective of this study was to evaluate the influence of different dairy substrates (cows’ milk and whey protein) on the formation and dispersion of Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus in two biofilm systems (mono‐species and multi‐species) on stainless steel at 25 °C. The dominant behaviour of E. faecalis occurred in most of the tests on mono‐species and multi‐species biofilms. A greater dispersion of biofilm cells was observed in skimmed milk.     

Tolerance evaluation in Salmonella enterica serovar Typhimurium challenged with sublethal amounts of Rosmarinus officinalis L. essential oil or 1,8‐cineole in meat model

The induction of direct bacterial tolerance and cross‐tolerance (NaCl, acid pH, high temperature) in Salmonella Typhimurium ATTC 14028 following the exposure to sublethal amounts of the essential oil from Rosmarinus officinalis L. (ROEO), and its major component 1,8‐cineole (CIN) was evaluated in this study. Direct protection was not induced when cells were exposed to 1/2 MIC and 1/4 MIC of ROEO or CIN in meat broth and in previously irradiated meat ground‐beef. Cells exposed to ROEO or CIN at sublethal amounts did not present cross‐protection to high temperature, lactic acid and NaCl. Likewise, cells progressively subcultured in meat broth containing increasing amounts of ROEO or CIN were able to survive only up to 1/4 MIC for both tested substances. From these results, S. Typhimurium ATCC 14028 was not capable to develop direct or cross‐tolerance when exposed to ROEO or CIN in a meat‐based growth media and was not able to develop direct tolerance in a meat‐based model.     

Control of Listeria monocytogenes Contamination in Ready‐to‐Eat Meat Products

The ubiquitous nature of Listeria monocytogenes and its ability to grow at refrigerated temperature makes L. monocytogenes a significant threat to the safety of ready‐to‐eat (RTE) meat products. The contamination by L. monocytogenes in RTE meat primarily occurs during slicing and packaging after cooking. The effectiveness of post‐package decontamination technology such as in‐package thermal pasteurization, irradiation, and high‐pressure processing are discussed. Formulating meat products with antimicrobial additives is another common approach to control L. monocytogenes in RTE meat. Irradiation is an effective technology to eliminate L. monocytogenes but can influence the quality of RTE meat products significantly. The effect of irradiation or the combination of irradiation and antimicrobials on the survival of L. monocytogenes and the quality of RTE meat is discussed.     

Reduction of Listeria monocytogenes in cold‐smoked salmon by bacteriophage P100, nisin and lauric arginate,singly or in combinations

Three GRAS antimicrobials including, lauric arginate (LAE), bacteriophage P100 (phage P100) and bacteriocin nisin, were evaluated either singly or in combinations for the reduction of initial load of Listeria monocytogenes in cold‐smoked salmon (CSS). The stability of phage P100 in the presence of LAE (200 ppm) and nisin (500 ppm) or at 10× and 100× of these concentrations was determined at 4 °C or 30 °C for 24 h in a broth model. Phage P100 was found to be highly stable in the presence of these antimicrobial agents as plaque‐forming units (PFU) did not vary between control and antimicrobial‐treated phage. The survival of L. monocytogenes in the presence of phage P100, nisin and LAE showed remarkable reduction within 24 h both at 4 °C or 30 °C in broth. Treatment of CSS containing 3.5 log CFU cm^?2 L. monocytogenes with phage P100 (10⁸ PFU mL^?1), nisin (500 ppm) and LAE (200 ppm) showed strong listericidal action and reduced the L. monocytogenes by 2–3 log CFU cm^?2 after 24 h. Among the combined treatments, phage P100 + LAE or nisin + LAE exhibited the most listericidal action in which L. monocytogenes cells were reduced to undetectable level within 24 h in CSS.     

Quantifying Listeria monocytogenes prevalence and concentration in minced pork meat and estimating performance of three culture media from presence/absence microbiological testing using a deterministic and stochastic approach

Listeria monocytogenes poses a serious threat to public health, and the majority of cases of human listeriosis are associated with contaminated food. Reliable microbiological testing is needed for effective pathogen control by food industry and competent authorities. The aims of this work were to estimate the prevalence and concentration of L. monocytogenes in minced pork meat by the application of a Bayesian modeling approach, and also to determine the performance of three culture media commonly used for detecting L. monocytogenes in foods from a deterministic and stochastic perspective. Samples (n = 100) collected from local markets were tested for L. monocytogenes using in parallel the PALCAM, ALOA and RAPID'L.mono selective media according to ISO 11290-1:1996 and 11290-2:1998 methods. Presence of the pathogen was confirmed by conducting biochemical and molecular tests. Independent experiments (n = 10) for model validation purposes were performed. Performance attributes were calculated from the presence–absence microbiological test results by combining the results obtained from the culture media and confirmative tests. Dirichlet distribution, the multivariate expression of a Beta distribution, was used to analyze the performance data from a stochastic perspective. No L. monocytogenes was enumerated by direct-plating (<10 CFU/g), though the pathogen was detected in 22% of the samples. L. monocytogenes concentration was estimated at 14–17 CFU/kg. Validation showed good agreement between observed and predicted prevalence (error = −2.17%). The results showed that all media were best at ruling in L. monocytogenes presence than ruling it out. Sensitivity and specificity varied depending on the culture-dependent method. None of the culture media was perfect in detecting L. monocytogenes in minced pork meat alone. The use of at least two culture media in parallel enhanced the efficiency of L. monocytogenes detection. Bayesian modeling may reduce the time needed to draw conclusions regarding L. monocytogenes presence and the uncertainty of the results obtained. Furthermore, the problem of observing zero counts may be overcome by applying Bayesian analysis, making the determination of a test performance feasible.     

Efficacies of Garlic and L. sakei in Wine‐Based Marinades for Controlling Listeria monocytogenes and Salmonella spp. in Chouriço de Vinho,a Dry Sausage Made from Wine‐Marinated Pork

Chouriço de vinho is made from roughly minced (10 to 30 mm) pork and fat, seasoned with a marinade made from wine, salt, garlic, and other facultative seasonings used according to the recipe of each producer. The batter is maintained at 4 to 7 ºC for 24 to 48 h. It is then stuffed into natural thin pork gut, cold smoked and matured at a low temperature for 1 to 4 wk. The effect of garlic used in wine‐based marinade and a starter culture of indigenous Lactobacillus sakei on the behavior of Listeria monocytogenes and Salmonella spp. in the processing of chouriço was investigated. The garlic (as powder and fresh juice) was found to contribute (P < 0.05) to the control of both pathogens in broth. Garlic dose, as tested within the usual limits used for seasoning, did not impact the reduction of pathogens. Garlic‐wine‐based marinade and a starter culture of indigenous L. sakei contribute to controlling L. monocytogenes and Salmonella spp. in the processing of chouriço. Their presence was responsible for the loss of viability of L. monocytogenes and Salmonella spp. following 5 d of drying, even sooner than situations where no garlic was used. The results of the present work show that the use of a wine‐based marinade with garlic has an important role in ensuring the safety of the product.     

Detection of Salmonella spp., Yersinia enterocolitica,Listeria monocytogenes and Campylobacter spp. by real‐time multiplex PCR using amplicon DNA melting analysis and probe‐based assay

Syto9 and probe‐based multiplex real‐time PCR assays for simultaneous detection of a group of foodborne pathogens (named SYLC group), targeting Salmonella spp. (invA gene), Yersinia enterocolitica (ystA gene), Listeria monocytogenes (hly gene) and Campylobacter spp. (rrna gene), have been developed. The Syto9 assay generates amplicon DNA melting curve with four peaks of 86.5 ± 0.5, 84 ± 0.5, 81.5 ± 0.5 and 90.5 ± 0.5 °C corresponding Salmonella spp., Y. enterocolitica, L. monocytogenes and Campylobacter spp. targets, respectively. The sensitivities of the Syto9 and TaqMan assays in artificially inoculated chicken wing rinses were in a range of 3.2 × 10² to 3.1 × 10⁴ and 9.8 × 10² to 1.9 × 10⁴ colony‐forming units per millilitre, respectively, depending on the pathogen. All tested target strains (n = 100) were correctly detected by the both assays, whereas nontarget strains (n = 100) demonstrated no cross‐reactivity representing 100% specificity. The assays are suitable for application in qualitative and quantitative detection of SYLC group pathogens in food matrices.     

Antimicrobial activities of spice extracts against pathogenic and spoilage bacteria in modified atmosphere packaged fresh pork and vacuum packaged ham slices stored at 4 °C

The antimicrobial activity of 14 spice extracts against four common meat spoilage and pathogenic bacteria (Listeria monocytogenes, Escherichia coli, Pseudomonas fluorescens and Lactobacillus sake) was screened in cultured media (experiment 1). The results showed that individual extracts of clove, rosemary, cassia bark and liquorice contained strong antimicrobial activity, but the mixture of rosemary and liquorice extracts was the best inhibitor against all four types of microbes. Subsequently, mixed rosemary/liquorice extracts were spray-applied to inoculated fresh pork in modified atmosphere packaging (experiment 2) and to inoculated ham slices in vacuum packaging (experiment 3). The meat samples were stored at 4 °C over a 28-day period and microbial growth was monitored regularly. The L. monocytogenes population on fresh pork by day 28 decreased 2.9, 3.1 and 3.6 logs, the MAB decreased 2.7, 2.9 and 3.1 logs, the Pseudomonas spp. count decreased 1.6, 2.1 and 2.6 logs and the total coliform count decreased 0.6, 0.8 and 1.2 logs, corresponding to 2.5, 5.0 and 10.0 mg/ml of spray, respectively, when compared to control (P < 0.05). The number of L. monocytogenes on ham slices decreased 2.5, 2.6 and 3.0 logs, the MAB plate counts decreased 2.9, 3.0 and 3.2 logs and the LAB counts decreased 2.4, 2.6 and 2.8 logs (P < 0.05), respectively, after 28-days, by the same levels of mixed rosemary/liquorice extract treatments. The results demonstrated strong potential of mixed rosemary and liquorice as a natural preservative in fresh pork and ham products.     

Effect of partial replacement of potassium lactate and sodium diacetate by natural green tea and grape seed extracts and postpackaging thermal treatment on the growth of Listeria monocytogenes in hotdog model system

Low‐ (5%) and high‐fat (20%) chicken and turkey hotdogs were formulated in three groups: no antimicrobials (control), chemical preservatives (potassium lactate and sodium diacetate) alone and partial replacement of chemical preservatives by green tea (GTE) and grape seed extracts (GSE), surface inoculated (c. 10³ CFU g^?1) with Listeria monocytogenes, treated with or without heat treatment (65 °C for 104 s) to determine the growth of L. monocytogenes until spoilage (28 days). Maximum growth inhibitions (c. 2.0 CFU g^?1) were observed in the treatments having chemical preservatives and plant extracts regardless of the meat and fat type. Furthermore, plant extracts along with chemical preservatives demonstrated additional inhibitory effect on the growth of L. monocytogenes survivors in chicken hotdog samples followed by postpackaging heat treatment. Results demonstrated that natural GTE and GSE can partially replace the chemical preservatives and further enhance the antilisterial activities when combined with heat treatment.     

Effects of Zataria multiflora boiss essential oil,ultraviolet radiation and their combination on Listeria monocytogenes biofilm in a simulated industrial model

The objective of this study was to investigate the inhibitory effect of Zataria multiflora boiss essential oils (ZEOs), ultraviolet (UV) radiation and their combination against Listeria monocytogenes biofilm in a simulated industrial model (SIM). The effect of minimal inhibitory concentration (MIC) and sub‐MIC concentration of ZEOs, different contact time of UV and their combination was evaluated in a SIM on 6‐ and 12‐day‐old L. monocytogenes biofilm. In a SIM, 0.3% ZEOs were adequate to completely eliminate 6‐ and 12‐day‐old biofilm grown on stainless steel coupons. The population of viable L. monocytogenes biofilm cells under a 15‐ to 45‐min contact time of UV treatment declined significantly at 6‐ and 12‐day‐old biofilm. The combined effect of ZEO and UV showed antagonist effects. These findings indicated that in the single use, ZEO and UV revealed a suitable antilisteria biofilm activity, while combining them is not a promising method to remove listeria biofilms from stainless steel surfaces.     

Microbial contamination associated with the processing of grilled pork,a ready-to-eat street food in Benin

This study aimed to assess the microbial contamination associated with the traditional processing of fresh pork into grilled pork in Benin. Sixty samples of meat, including fresh pork and processed pork were randomly collected from different processing/selling sites, and the main foodborne microorganisms were sought using standard methods. The Aerobic Mesophilic Bacteria load in all samples ranged between 2.7 and 7.4 Log₁₀ CFU g⁻¹, with 16.7% of samples exceeding the acceptable limit of <7.0 Log₁₀ CFU g⁻¹ recommended by the Health Protection Agency for this criterion. Likewise, Enterobacteriaceae, Escherichia coli, and Clostridium perfringens loads exceeded the acceptable limit in 20.8, 20.8, and 12.5% of the samples, respectively. None of the samples contained Salmonella spp., Staphylococcus aureus or Listeria monocytogenes. Sources of contamination of grilled pork were identified and grouped into five types of causes related to processors, processing methods, equipment used, raw materials, and processing/selling environment. Similarly, a microbiological hazard analysis of grilled pork processing practices identified the sensitive steps where additional hygiene measures needed to be implemented.     

Inactivation of Listeria monocytogenes on agar and processed meat surfaces by atmospheric pressure plasma jets

An apparatus for generating atmospheric pressure plasma (APP) jet was used to investigate the inactivation of Listeria monocytogenes on the surface of agar plates and slices of cooked chicken breast and ham. He, N₂ (both 7 L/min), and mixtures of each with O₂ (0.07 L/min) were used to produce the plasma jets. After treatment for 2 min with APP jets of He, He + O₂, N₂, or N₂ + O₂, the numbers of L. monocytogenes on agar plates were reduced by 0.87, 4.19, 4.26, and 7.59 log units, respectively. Similar treatments reduced the L. monocytogenes inoculated onto sliced chicken breast and ham by 1.37 to 4.73 and 1.94 to 6.52 log units, respectively, according to the input gas used with the N₂ + O₂ mixture being the most effective. Most APP jets reduced the numbers of aerobic bacteria on the meat surfaces to <10² CFU/g, and the numbers remained below that level of detection after storage at 10 °C for 7 days. The results indicate that APP jets are effective for the inactivation of L. monocytogenes on sliced meats and for prolonging the shelf-life of such foods.     

Effects of supercritical carbon dioxide treatment against generic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and E. coli O157:H7 in marinades and marinated pork

This study was conducted to evaluate the effects of supercritical carbon dioxide (SC-CO₂) treatment on soy sauce and hot-pepper paste marinades, as well as in marinated pork products, for the inhibition of generic Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, and E. coli O157:H7. SC-CO₂ was more effective at destroying foodborne pathogens when it was applied to the marinades than the marinated products. SC-CO₂ treatment at 14 MPa and 45 °C for 40 min resulted in a greater reduction in soy sauce (2.52–3.47 log CFU/cm²) than in hot-pepper paste marinade (2.12–2.72 log CFU/cm²). In the case of the marinated pork, when SC-CO₂ was applied at 14 MPa and 45 °C for 40 min, the reduction levels of L. monocytogenes were 2.49 and 1.92 log CFU/cm² in soy sauce and hot-pepper paste marinated pork, respectively. The results should be useful in the meat industry to help increase microbial safety and assure the microbial stability of marinades and marinated products.     

Effect of nisin‐producing Lactococcus lactis starter cultures on the inhibition of two pathogens in ripened cheeses

The effect of Lactococcus lactis nisin‐producing strains, isolated from Italian fermented foods, on the survival of two foodborne pathogens namely Listeria monocytogenes and Staphylococcus aureus was investigated in experimental cheese production. One of the three Lactobacillus lactis nisin innoculated as starters, Lactobacillus lactis 41FL1 lowered S. aureus count by 1.73 log colony‐forming units (cfu)/g within the first 3 days, reaching the highest reduction, 3.54 log cfu/g, by the end of ripening period of 60 days. There was no effect on L. monocytogenes. The application of L. lactis 41FL1 as bioprotective culture in controlling S. aureus shows considerable promise.     

Modeling Surface Transfer of Listeria monocytogenes on Salami during Slicing

ABSTRACT: Listeria monocytogenes has been implicated in several listeriosis outbreaks linked to the consumption of presliced ready‐to‐eat (RTE) deli meats, which has drawn considerable attention in regard to possible cross‐contamination during slicing operation at retail and food service environments. Salami with 15% fat (a moderate fat content deli item) was used to investigate the transfer of L. monocytogenes between a meat slicer and salami slices and to understand its impact on food safety. A 6‐strain cocktail of L. monocytogenes was inoculated onto a slicer blade to an initial level of approximately 3, 5, 6, 7, or 9 log CFU/blade (or approximately 2, 4, 5, 6, or 8 log CFU/cm² of the blade edge area), and then the salami was sliced to a thickness of 1 to 2 mm (case I). For another cross‐contamination scenario, a clean blade was first used to slice salami loaf that was previously surface‐inoculated with L. monocytogenes (approximately 3, 5, 6, 7, 8, or 9 log CFU/100 cm² area), followed by slicing the uninoculated salami loaf (case II). The salami slicing rate was maintained at an average of 3 to 4 slices per minute in all the tests. The results showed that the empirical models developed in this study were reasonably accurate in describing the transfer trend/pattern of L. monocytogenes between the blade and salami slices if the inoculum level was > 5 log CFU on the salami or blade. With an initial inoculum at 3 or 4 log CFU, the experimental data seemed to suggest a rather random pattern of bacterial transfer between blade and salami. The currently developed models are microbial load (n), sequential slice index (X), and contamination route dependent, which might limit their applications to certain conditions. However, the models may be further applied to predict the 3 or 4 log CFU level (and below) cross‐contamination of salami slicing process. Considering only few data are available in the literature regarding food pathogen surface transfer, the empirical models may provide a useful tool in building risk assessment procedures.     

Modeling dependence of growth inhibition of Salmonella Typhimurium and Listeria monocytogenes by oregano or thyme essential oils on the chemical composition of minced pork

The aim of this study was to compare the antimicrobial effect of selected essential oils (EOs) at concentration of 1% in minced pork from five different meat cuts (loin, ham, shoulder, neck, and belly) and to assess the influence of the chemical parameters of meat on EO efficiency, determined by the decrease of pathogens in comparison to a control in samples after storage at 3°C/7 d in a vacuum. The inhibition was significant (p < .05) only in minced pork from meat cuts with a fat content lower than 5% (leg, loin and shoulder). Salmonella enterica serovar Typhimurium was more sensitive than Listeria monocytogenes and oregano was more effective than thyme (p < .001). The inhibition of S. Typhimurium depended mainly on the fat content (logarithmic dependence) and to a lesser degree on the pH, whereas pH was not found to be a significant predictor in the case of L. monocytogenes. The results of this study show that only lean minced meat (with a fat content max. 5%) is a suitable matrix for pathogen control by EOs.