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Despite the wide variety of native and exotic fruits in Brazil, there is limited understanding of their ability to support pathogens during storage. This study aimed to evaluate the behavior of Salmonella enterica and Listeria monocytogenes inoculated into the pulp of eight fruits native and exotic to Brazil: Jenipapo (Genipa americana L.), Umbu (Spondias tuberosa Arruda), Maná (Solanum sessiliflorum), Cajá-manga (Spondias dulcis), Physalis (Physalis angulata L.), Feijoa (Acca sellowiana), Cupuaçu (Theobroma grandiflorum) (average pH < 3.3) and in a low acidy fruit: Abiu (Pouteria caimito) (pH 6.11). The pathogens were inoculated into the different fruits and stored at 10, 20, 30 and 37 °C for up to 12 h and 6 days, respectively. Among the fruits evaluated, Abiu was the only one that allowed Salmonella growth, showing higher δ-values at 20 and 30 °C (5.6 log CFU/g for both temperatures). For Physalis and Feijoa, there was a small reduction in the pathogen concentration (<1 log-cycle), mainly at 10 and 20 °C, indicating its ability to remain in the matrices. For the other fruits, notable negative δ-values were obtained, indicating a tendency towards microbial inactivation. The survival potential was significantly affected by temperature in Abiu, Maná, Cupuaçu, and Cajá-manga (p < 0.05). The same phenomena regarding δ-value were observed for L. monocytogenes population, with the greatest survival potential observed at 20 °C in Abiu (3.3 log CFU/g). Regarding the exponential growth rates in Abiu, the highest values were observed at 30 and 37 °C, both for Salmonella (4.6 and 4.9 log (CFU/g)/day, respectively) and for L. monocytogenes (2.8 and 2.7 log (CFU/g)/day, respectively), with no significant difference between both temperatures. Regarding microbial inactivation, L. monocytogenes showed greater resistance than Salmonella in practically all matrices. Jenipapo and Umbu were the pulps that, in general, had the greatest effect on reducing the population of pathogens. Furthermore, the increase in storage temperature seems to favor the increase on inactivation rates. In conclusion, Salmonella and L. monocytogenes can grow only in Abiu pulp, although they can survive in some acidic tropical fruits kept at refrigeration and abusive temperatures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study determined the susceptibility to sanitizers and biofilm-forming ability on stainless steel of 43 Salmonella enterica and Listeria monocytogenes strains. Besides, the biofilm resistance to sanitizers of four bacterial pathogen strains was evaluated. Four sanitizers commonly used in the food industry were tested: peracetic acid (PAA), chlorine dioxide (ClO 2 ), sodium hypochlorite (SH), and quaternary ammonium compound (QAC). The susceptibility to sanitizers varied widely among the strains of both pathogens. On the other hand, the number of biofilm-associated cells on the stainless-steel surface was >5 log CFU/cm 2 for all of them. Only one Salmonella strain and two L. monocytogenes strains stood out as the least biofilm-forming. The resistance of biofilms to sanitizers also varied among strains of each pathogen. Biofilms of L. monocytogenes were more susceptible to the disinfection process with ClO 2 and QAC than those of Salmonella. However, no correlation was observed between the ability to form denser biofilm and increased sanitizer resistance. In general, chlorine compounds were more effective than other sanitizers in inactivating planktonic cells and biofilms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

This study aimed to estimate the risk of listeriosis from the consumption of pasteurized milk in Brazil, comparing conventional treatment with the technology of thermosonication. The Quantitative Microbiological Risk Assessment (QMRA) model was developed, covering the entire milk production chain, from milking to the moment of consumption. In general, higher risks were observed in association with higher initial concentrations of the pathogen and the vulnerable population. The highest risk predicted (3.67 × 10 -5 ) was related to the scenario considering the initial concentration range of L. monocytogenes between 4 and 6 log CFU/mL, with conventional treatment and considering the vulnerable population, resulting in one case of listeriosis every 27,248 servings. When considering thermosonication treatment, lower risks have been predicted. The scenario analysis indicated that the steps related to storage conditions in retail and at the consumer's home (post-processing steps) are the most influential in the associated risk, in all scenarios. The predictive parameters of inactivation related to the applied treatment also have a considerable influence on the risk. The results point to the influence of the stages of the dairy production chain and the thermosonication treatment applied in the food safety of milk, subsidizing information for industrial application and for regulatory agencies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Listeria monocytogenes of varied sources including food-related sources may reach the soil. Associated food safety and environmental health risks of such contamination depend significantly on the capacity of L. monocytogenes to survive in the soil. This study assessed the survival of 13 L. monocytogenes strains isolated from food and food processing environments and a cocktail of three of the strains in two types of soils (loam and sandy) under controlled temperature conditions: 5, 10, 20, 25, 30℃ and 'uncontrolled' ambient temperature conditions in a tropical region. The impact of compost amendment on the survival of L. monocytogenes in the two different types of soils was also assessed. Soil type, temperature and compost amendment significantly (P <0.001) impacted the survival of L. monocytogenes in soil. Temperature variations affected the survival of L. monocytogenes in soil, where some strains such as strain 732, a L. monocytogenes 1/2a strain survived better at lower temperature (5°C), for which counts of up to 10.47 ± 0.005 log CFU/g were recovered in compost-amended sandy soil, 60 days post-inoculation. Some other strains such as strain 441, a L. monocytogenes 1/2a survived best at intermediate temperature (25 and 30 °C), while others such as 2739 (L. monocytogenes 1/2b) thrived at higher temperature (between 30 °C - 37 °C). There were significant correlations between the influence of temperature and soil type, where lower temperature conditions (5°C - 20°C) were generally more suitable for survival in sandy soil compared to higher temperature conditions. For some of the strains that thrived better in sandy soil at lower temperature, Pearson correlation analysis found significant correlations between temperature and soil type. Steady, controlled temperature generally favored the survival of the strains compared to uncontrolled ambient temperature conditions, except for the cocktail. The cocktail persisted until the last day of post-inoculation storage (60th day) in all test soils and under all incubation temperature conditions. Loam soil was more favorable for the survival of L. monocytogenes and compost amendment improved the survival of the strains, especially in compost-amended sandy soil. Listeria monocytogenes may exhibit variable survival capacity in soil, depending on conditions such as soil type, compost amendment and temperature., Competing Interests: Declaration of competing interest Authors declare that they have no competing interests., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The survival kinetics of Listeria monocytogenes (9 log CFU/mL) as a post-fermentation contaminant in probiotic fermented milk (Lactobacillus acidophilus La-5, 8-9 log CFU/mL) processed with milk subjected to ohmic heating (0, 4, 6, and 8 V/cm; CONV, OH 4 , OH 6 , OH 8 , 90-95 °C/5 min) was investigated using Weibull predictive model. Additionally, the presence of bioactive compounds (antioxidant activity, inhibition of the enzymes α-glucosidase, α-amylase, and angiotensin-converting) and sensory analysis (consumer test) of probiotic fermented milks were evaluated. Overall, OH provided a decrease in the viability of Listeria monocytogenes, suitable Lactobacillus acidophilus counts, and satisfactory results in the gastrointestinal tract survival. The Weibull model presented an excellent fit to the data of all conditions. Furthermore, lower δ values (217-298 against 665 h, CONV), and increased R 2 values (0.99 against 0.98, CONV) were obtained for the OH-treated samples, emphasizing the best performance of OH data. In addition, OH improved the generation of bioactive compounds as well as the sensory acceptance. Indeed, considering functional and safety purposes, OH presented as an interesting technology to be used in milk for manufacturing probiotic fermented milk., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The fate of Listeria monocytogenes during ripening of artisanal Minas semi-hard cheese, as influenced by cheese intrinsic properties and by autochthonous (naturally present) or intentionally-added anti-listerial lactic acid bacteria (LAB) was modeled. Selected LAB strains with anti-listerial capacity were added or not to raw or pasteurized milk to prepare 4 cheese treatments. Counts of LAB and L. monocytogenes, pH, temperature and water activity were determined throughout cheese ripening (22 days, 22±1ᵒC). Different approaches were adopted to model the effect of LAB on L. monocytogenes: an independent approach using the Huang primary model to describe LAB growth and the linear decay model to describe pathogen inactivation; the Huang-Cardinal [pH] model using the effect of pH variation in a dynamic tertiary approach; and the Jameson-effect with N max tot model which simultaneously describes L. monocytogenes and LAB fate. L. monocytogenes inactivation occurred in both treatments with added LAB and inactivation was faster in raw milk cheese (-0.0260 h -1 ) vs. pasteurized milk cheese (-0.0182 h -1 ), as estimated by the linear decay model. Better goodness-of-fit was achieved for the cheeses without added LAB when the Huang primary model was used. A faster and great pH decline was detected for cheeses with added LAB, and the Huang-Cardinal [pH] model predicted higher pathogen growth rate in cheese produced with raw milk, but greater L. monocytogenes final concentration in pasteurized milk cheese. The Jameson-effect model with N max tot predicted that LAB suppressed pathogen growth in all treatments, except in the treatment with pasteurized milk and no LAB addition. The Huang-Cardinal [pH] model was more accurate in modeling L. monocytogenes kinetics as a function of pH changes than was the Jameson-effect model with N max tot as a function of LAB inhibitory effect based on the goodness-of-fit measures. The Jameson-effect model may however be a better competition model since it can more easily represent L. monocytogenes growth and death. This study presents crucial kinetic data on L. monocytogenes behavior in the presence of competing microbiota in Minas semi-hard cheese under dynamic conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study compares dynamic tertiary and competition models for L. monocytogenes growth as a function of intrinsic properties of a traditional Brazilian soft cheese and the inhibitory effect of lactic acid bacteria (LAB) during refrigerated storage. Cheeses were prepared from raw or pasteurized milk with or without the addition of selected LAB with known anti-listerial activity. Cheeses were analyzed for LAB and L. monocytogenes counts, pH and water activity (a w ) throughout cold storage. Two approaches were used to describe the effect of LAB on L. monocytogenes: a Huang-Cardinal model that considers the effect of pH and a w variation in a dynamic kinetic analysis framework; and microbial competition models, including Lotka-Volterra and Jameson-effect variants, describing the simultaneous growth of L. monocytogenes and LAB. The Jameson-effect with γ and the Lotka-Volterra models produced models with statistically significant coefficients that characterized the inhibitory effect of selected LAB on L. monocytogenes in Minas fresh cheese. The Huang-Cardinal model [pH] outperformed both competition models. Taking a w change into account did not improve the fit quality of the Huang-Cardinal [pH] model. These models for Minas soft cheese should be valuable for future microbial risk assessments for this culturally important traditional cheese., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Artisanal raw milk cheeses are highly appreciated dairy products in Brazil and ensuring their microbiological safety has been a great need. This study reports the isolation and characterization of lactic acid bacteria (LAB) strains with anti-listerial activity, and their effects on Listeria monocytogenes during refrigerated shelf-life of soft Minas cheese and ripening of semi-hard Minas cheese. LAB strains (n = 891) isolated from Minas artisanal cheeses (n = 244) were assessed for anti-listerial activity by deferred antagonism assay at 37 °C and 7 °C. The treatments comprised the production of soft or semi-hard Minas cheeses using raw or pasteurized milk, and including the addition of selected LAB only [Lactobacillus brevis 2-392, Lactobacillus plantarum 1-399 and 4 Enterococcus faecalis (1-37, 2-49, 2-388 and 1-400)], L. monocytogenes only, selected LAB co-inoculated with L. monocytogenes, or without any added cultures. At 37 °C, 48.1% of LAB isolates showed anti-listerial capacity and 77.5% maintained activity at 7 °C. Selected LAB strains presented a bacteriostatic effect on L. monocytogenes in soft cheese. L. monocytogenes was inactivated during the ripening of semi-hard cheeses by the mix of LAB added. Times to attain a 4 log-reduction of L. monocytogenes were 15 and 21 days for semi-hard cheeses produced with raw and pasteurized milk, respectively. LAB with anti-listerial activity isolated from artisanal Minas cheeses can comprise an additional barrier to L. monocytogenes growth during the refrigerated storage of soft cheese and help shorten the ripening period of semi-hard cheeses aged at ambient temperature., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The aim of this study was to perform a meta-analysis of the effects of sanitizing treatments of fresh produce on Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. From 55 primary studies found to report on such effects, 40 were selected based on specific criteria, leading to more than 1,000 data on mean log reductions of these three bacterial pathogens impairing the safety of fresh produce. Data were partitioned to build three meta-analytical models that could allow the assessment of differences in mean log reductions among pathogens, fresh produce, and sanitizers. Moderating variables assessed in the meta-analytical models included type of fresh produce, type of sanitizer, concentration, and treatment time and temperature. Further, a proposal was done to classify the sanitizers according to bactericidal efficacy by means of a meta-analytical dendrogram. The results indicated that both time and temperature significantly affected the mean log reductions of the sanitizing treatment (P < 0.0001). In general, sanitizer treatments led to lower mean log reductions when applied to leafy greens (for example, 0.68 log reductions [0.00 to 1.37] achieved in lettuce) compared to other, nonleafy vegetables (for example, 3.04 mean log reductions [2.32 to 3.76] obtained for carrots). Among the pathogens, E. coli O157:H7 was more resistant to ozone (1.6 mean log reductions), while L. monocytogenes and Salmonella presented high resistance to organic acids, such as citric acid, acetic acid, and lactic acid (∼3.0 mean log reductions). With regard to the sanitizers, it has been found that slightly acidic electrolyzed water, acidified sodium chlorite, and the gaseous chlorine dioxide clustered together, indicating that they possessed the strongest bactericidal effect. The results reported seem to be an important achievement for advancing the global understanding of the effectiveness of sanitizers for microbial safety of fresh produce., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)

This study was aimed at determining the effects of different storage scenarios on the growth potential of Salmonella strains and Listeria monocytogenes in ready-to-eat (RTE) mixes of iceberg and crisp lettuces (Lactuca sativa) and collard greens (Brassica oleracea). Vegetables were submitted to minimal processing, experimentally contaminated to achieve 10(1) and 10(2) CFU/g, packed under modified atmosphere and in perforated film, and submitted to the following storage scenarios: I = 100 % of the shelf life (6 days) at 7°C; II = 70 % of shelf life at 7°C and 30 % at 15°C; III = 30 % at 7°C and 70 % at 15°C; IV = 100 % at 15°C. Higher populations of Salmonella were observed in lettuce mixes than in collard greens; the opposite occurred with L. monocytogenes. Keeping the RTE vegetables at 15°C during the whole shelf life (scenario IV) or part of it (scenarios II and III) markedly influenced the growth of both pathogens in most of the scenarios studied (P < 0.05). Growth potentials of strains of Salmonella and L. monocytogenes were significantly different depending on the scenarios in samples packed with perforated film in comparison to those stored under modified atmosphere (P < 0.05). The findings indicate that even contamination as low as 10(1) CFU/g can lead to high populations if there is temperature abuse during storage (15°C). This study of the behavior of Salmonella and L. monocytogenes in RTE vegetables provides insights that may be useful in the development of strategies to control pathogen growth in these products.

Growth potential (δ) is defined as the difference between the population of a microorganism at the end of shelf-life of specific food and its initial population. The determination of δ of Salmonella and Listeria monocytogenes in RTE vegetables can be very useful to determine likely threats to food safety. However, little is known on the behavior of these microorganisms in several RTE vegetables. Therefore, the aim of this study was to determine the δ of both pathogens in nine different types of RTE vegetables (escarole, collard green, spinach, watercress, arugula, grated carrot, green salad, and mix for yakisoba) stored at refrigeration (7°C) and abuse temperature (15°C). The population of aerobic microorganisms and lactic acid bacteria, including those showing antimicrobial activity has been also determined. Results indicated that L. monocytogenes was able to grow (δ≥0.5 log(10)) in more storage conditions and vegetables than Salmonella. Both microorganisms were inhibited in carrots, although a more pronounced effect has been observed against L. monocytogenes. The highest δ values were obtained when the RTE vegetables were stored 15°C/6days in collard greens (δ=3.3) and arugula (δ=3.2) (L. monocytogenes) and arugula (δ=4.1) and escarole (δ=2.8) (Salmonella). In most vegetables and storage conditions studied, the counts of total aerobic microorganisms raised significantly independent of the temperature of storage (p<0.05). Counts of lactic acid bacteria were higher in vegetables partially or fully stored at abuse temperature with recovery of isolates showing antimicrobial activity. In conclusion, the results of this study show that Salmonella and L. monocytogenes may grow and reach high populations in RTE vegetables depending on storage conditions and the definition of effective intervention strategies are needed to control their growth in these products., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The growth parameters (growth rate, μ and lag time, λ) of three different strains each of Salmonella enterica and Listeria monocytogenes in minimally processed lettuce (MPL) and their changes as a function of temperature were modeled. MPL were packed under modified atmosphere (5% O₂, 15% CO₂ and 80% N₂), stored at 7-30 °C and samples collected at different time intervals were enumerated for S. enterica and L. monocytogenes. Growth curves and equations describing the relationship between μ and λ as a function of temperature were constructed using the DMFit Excel add-in and through linear regression, respectively. The predicted growth parameters for the pathogens observed in this study were compared to ComBase, Pathogen modeling program (PMP) and data from the literature. High R² values (0.97 and 0.93) were observed for average growth curves of different strains of pathogens grown on MPL. Secondary models of μ and λ for both pathogens followed a linear trend with high R² values (>0.90). Root mean square error (RMSE) showed that the models obtained are accurate and suitable for modeling the growth of S. enterica and L. monocytogenes in MP lettuce. The current study provides growth models for these foodborne pathogens that can be used in microbial risk assessment., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Listeria monocytogenes is a foodborne pathogen of great concern due to the high fatality rates of listeriosis. The consumption of RTE vegetables has increased in Brazil over the last two decades, but little is known about the risks associated to the consumption of these products. This study evaluated the prevalence and counts of L. monocytogenes in 512 packages of ready-to-eat vegetables marketed in São Paulo. The isolates were characterized for their serotypes, ribotypes, positivity for virulence genes inlA, inlC and inlJ, resistance to chlorine, growth rate variability and capability to form biofilm on stainless steel (AISI 304, #4) coupons. L. monocytogenes was detected in 3.1% of the samples. Only five samples presented countable levels, with counts between 1.0×10(1) and 2.6×10(2)CFU/g. Isolates belonged to serotypes 1/2b or 4b and most were positive for genes inlC and inlJ. Ribotypable isolates were grouped into four groups: 1038 (69.4%), 19175 (11.3%), 19191 (17.7%) and 18604 (one isolate). Most isolates survived to exposure to 125 ppm of a chlorine-based disinfectant for 3 min. All isolates were capable to attach to the coupons, reaching counts above 4 log(10) CFU/cm(2) and the growth rate (μ) at 25°C of the majority of the isolates varied between 0.1 and 0.2 log OD/h, but for few strains the μ was as high as 0.26 log OD/h. Results of this survey indicate that RTE vegetables may be vehicles of L. monocytogenes strains with limited variation in serotype, ribotype and virulence factors but varying significantly in resistance to chlorine disinfectants, capability of forming biofilm and growth rate. Data obtained is of foremost importance to serve as baseline for the development of scientific-based policies to control the incidence of L. monocytogenes in RTE vegetables in Brazil., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The behaviour of Listeria monocytogenes in the fresh coconut water stored at 4 degrees C, 10 degrees C and 35 degrees C was studied. The coconut water was aseptically extracted from green coconuts (Cocos nucifera L.) and samples were inoculated in triplicate with a mixture of 5 strains of L. monocytogenes with a mean population of approximately 3 log(10) CFU/mL. The kinetic parameters of the bacteria were estimated from the Baranyi model, and compared with predictions of the Pathogen Modelling Program so as to predict its behaviour in the beverage. The results demonstrated that fresh green coconut water was a beverage propitious for the survival and growth of L. monocytogenes and that refrigeration at 10 degrees C or 4 degrees C retarded, but did not inhibit, growth of this bacterium. Temperature abuse at 35 degrees C considerably reduced the lagtimes. The study shows that L. monocytogenes growth in fresh green coconut water is controlled for several days by storage at low temperature, mainly at 4 degrees C. Thus, for risk population this product should only be drunk directly from the coconut or despite the sensorial alterations should be consumed pasteurized.

The current study was carried out to estimate the risks of infection due to consumption of RTE vegetables contaminated with Salmonella and Listeria monocytogenes in Brazil. The risk assessment model was composed of five different modules comprising the retail-consumption steps. Scenarios were simulated using prevalence and concentration levels reported in RTE vegetables in Brazil as well as considering values 10 times lower. In addition, scenarios in which temperature during transportation and storage are maintained below 5 °C were also evaluated. Models built in Excel spreadsheets were run (100,000 iterations) using @Risk software. The two outputs were risk of infection per month (probability of infection per month due to consumption of RTE vegetables) and number of infections per month (number of people that consumed RTE vegetables and get infected per month). The QMRA models predicted that the mean risk of Salmonella infection per month is 5.7E-03, while the mean risk of infection for L. monocytogenes was 8.1E-06 per month. The reduction of prevalence of Salmonella from 1.7% to 0.17% resulted in a decrease of risk of infection per month by about 6 times. In the case of L. monocytogenes, the reduction of prevalence from 2.2% to 0.22% resulted in decrease of risk of infection from 8.1E-06 to 1.0E-06. The risks and number of cases predicted in scenarios in which temperature was kept below 5 °C were reduced for both pathogens studied when compared to scenarios where this was not the case. The scenario where prevalence and concentration of pathogens was reduced and where temperature was <5 °C led to the lowest number of infections due by Salmonella and L. monocytogenes (187 and 3.3E-05 cases, respectively). The results suggest that effective mitigation strategies need to be adopted. The strict control of temperature during transportation, storage and consumption was more effective to reduce risk and number of cases due to L. monocytogenes than to Salmonella. More data is needed to improve the accuracy of risk assessment models developed. [ABSTRACT FROM AUTHOR]

Abstract: The growth parameters (growth rate, μ and lag time, λ) of three different strains each of Salmonella enterica and Listeria monocytogenes in minimally processed lettuce (MPL) and their changes as a function of temperature were modeled. MPL were packed under modified atmosphere (5% O2, 15% CO2 and 80% N2), stored at 7–30 °C and samples collected at different time intervals were enumerated for S. enterica and L. monocytogenes. Growth curves and equations describing the relationship between μ and λ as a function of temperature were constructed using the DMFit Excel add-in and through linear regression, respectively. The predicted growth parameters for the pathogens observed in this study were compared to ComBase, Pathogen modeling program (PMP) and data from the literature. High R2 values (0.97 and 0.93) were observed for average growth curves of different strains of pathogens grown on MPL. Secondary models of μ and λ for both pathogens followed a linear trend with high R2 values (>0.90). Root mean square error (RMSE) showed that the models obtained are accurate and suitable for modeling the growth of S. enterica and L. monocytogenes in MP lettuce. The current study provides growth models for these foodborne pathogens that can be used in microbial risk assessment. [Copyright &y& Elsevier]

This study aimed to assess the behavior of endogenous microbiota (total mesophilic and psychrotrophic bacteria) during the ripening period and of L. monocytogenes and lactic acid bacteria (LAB) during storage at 5, 10, and 20 °C of artisanal Canastra cheeses packed in a silver nanoparticles packaging system using a predictive modeling approach. The tested packaging system did not influence the initial values of pH (around 5.0) or aw (around 0.95) over the storage. Based on the mathematical parameters obtained by the Weibull predictive model, the active packaging system tested did not inactivate L. monocytogenes during the storage period of artisanal Canastra cheeses. Nonetheless, the findings indicate that the polyethylene packaging system containing silver nanoparticles (3000 ppm active based on silicon dioxide and silver) did not affect endogenous bacteria of Canastra cheese during ripening and storage, which opens the opportunity for the use of this material without compromising the role of these bacteria during cheese ripening, contributing to characteristics of the product's identity. • Silver nanoparticle pack (SNP) did not kill L. monocytogenes over cheese storage. • SNP did not affect endogenous bacteria of the cheese during ripening and storage. • SNP can be used to avoid recontamination of cheese thru ripening and further steps. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a total of 172 samples of minimally processed vegetables (MPV) were collected from supermarkets in the city of Campinas, Brazil. The MPV were analyzed using traditional and/or alternative methods for total aerobic mesophilic bacteria, total coliforms, Escherichia coli, coagulase positive staphylococci, Salmonella and Listeria monocytogenes. All the MPV analyzed presented populations of aerobic mesophilic microorganisms and total coliforms were >4 log10 CFU/g and 1.0–3.4 log10 CFU/g, respectively. E. coli was enumerated in only 10 samples out of 172 collected, while none of the 172 samples of MPV presented contamination by coagulase positive Staphylococcus (<101 CFU/g). Among the four methods used for detection of Salmonella in MPV (Vidas, 1,2 Test, Reveal, and Traditional), when Reveal was used a total of 29 positive samples were reported. For L. monocytogenes, the four methods tested (Vidas, Vip, Reveal, and traditional) performed similarly. The presence of Salmonella and L. monocytogenes in MPV was confirmed in one (watercress) and two samples (watercress and escarole), respectively. In conclusion, it has been observed that the microbiological quality of MPV commercialized in Campinas is generally satisfactory. Besides, the choice of microbiological method should be based not only on resource and time issues, but also on parameters such as sensitivity and specificity for the specific foods under analysis. [Copyright &y& Elsevier]

Listeriosis is a severe disease/infection which affects humans and animals and occurs as an invasive/non-invasive form caused by Listeria monocytogenes. This bacterium contaminates food during processing, distribution and even refrigerated storage. The high mortality rate associated with this disease makes it a paramount global health concern. Due to the life-threatening nature of this infection, there is a need for prompt treatment/biocontrol agents to improve food safety against L. monocytogenes. The great interest garnered by natural bioactive compounds in the last decades and the increased demands of natural, nutritional and healthy food by consumers have led to many researchers to investigate the listericidal activity of phenolic compounds. In the present review, polyphenols with antilisterial activity will be discussed as well as the mechanisms of action against biofilm formation and growth. The results of studies carried out to test different vegetable extracts and isolated phenolic compounds along with considerations about the application method in food were also covered in the review. Polyphneols, especially phenolic acids and flavonoids have a central role in the inhibition of L. monocytogenes as well as its capacity to form biofilms and cause eventual food outbreaks. The antilisterial effect of polyphenols is dependent of the extract composition, food matrix, and processing and storage conditions. The inhibitory effect of polyphenols were reported in food products (especially meat and meat products) during different storage conditions which support the role of polyphenols as food preservatives against L. monocytogenes. [Display omitted] • Phenolic acids and flavonoids inactivate L. monocytogenes by multiple mechanisms. • Polyphenols affect bacterial membrane and inhibit surface adhesion to food. • Structure of polyphenols play a central role in the inactivation of L. monocytogenes. • Polyphenols synergistically inhibit L. monocytogenes growth with nisin. [ABSTRACT FROM AUTHOR]

In this study a total of 220 isolates of lactic acid bacteria (LAB) recovered from 10 types of Brazilian artisanal cheeses marketed in 4 main regions of Brazil were evaluated regarding their safety and ability to produce diacetyl (a precursor of aromatic compounds), exopolysaccharides (EPS; from different sugar sources), and antagonistic activity against Listeria monocytogenes and Staphylococcus aureus. The results indicated that 131 isolates (59.6%) were classified as strong (40.5%) and moderate (19.1%) diacetyl producers; 28 isolates (12.7%) stood out due to their remarkable production of EPS from different sugars, including sucrose (3.2%), fructose (2.3%), lactose (2.3%), and glucose (6%). Furthermore, 94.1% and 95.9% of isolates presented antagonistic activity against S. aureus and L. monocytogenes , respectively, even though only 27 isolates (12.3%) exhibited positive results in the bacteriocin production test. None of the isolates tested presented hemolytic activity, and 117 were classified as safe, due to their intrinsic resistance to a maximum of 4 different antibiotics. The data obtained for assessment of antibiogram profile and technological potential (moderate and high production of diacetyl, EPS, and bacteriocins) were submitted to a multiple correspondence analysis to correlate them with the cheese of isolation. Regarding the antimicrobial profile of LAB strains, it was possible to verify an association between isolates from Minas artisanal cheeses from Araxá and resistance to tetracycline; Minas artisanal cheeses from Serro and resistance to erythromycin; Coalho and Minas artisanal cheese from Cerrado and resistance to penicillin; and isolates from Serrano and Colonial cheeses with clindamycin and ceftazidime resistance. Although the susceptibility of strains to these antibiotics was considered high (71.8–80.5%), these data may be related to the horizontal transfer of genes in the production chain of these cheeses. Results of multiple correspondence analysis also showed that isolates with antagonistic activity were mostly isolated from Manteiga, Colonial, and Coalho cheeses. The isolates with high or moderate EPS-producer ability from sucrose, glucose, and fructose were mainly associated with Minas artisanal cheeses from Cerrado. In contrast, isolates with high or moderate EPS-producer ability from lactose were isolated from Serrano, Minas artisanal cheeses from Canastra, and Campo das Vertentes microregions. Finally, isolates from Minas artisanal cheeses (from Araxá microregion), Coalho, and Caipira cheeses were associated with moderate/high diacetyl production. To the best of the authors' knowledge, this study provides, for the first time, data indicating that the dominant technological, biopreservative, and safety properties of LAB isolates can be correlated with the type of Brazilian artisanal cheeses, which denotes its singularity. This knowledge is of utmost relevance for the development of starter or adjunct cultures with tailored properties. [ABSTRACT FROM AUTHOR]

This study estimated the risk of listeriosis from Brazilian cheese consumption using quantitative microbial risk assessment (QMRA). Risks associated to consumption of two cheese types were assessed: artisanal ripened semi-hard cheese (produced with raw milk) and refrigerated fresh soft cheese (produced with pasteurized milk). The semi-hard cheese model predicted Listeria monocytogenes growth or decline during ripening, while the soft cheese model predicted pathogen growth during refrigerated storage. Semi-hard cheese modeling scenarios considered L. monocytogenes starting concentration from −2.4 to 6 log CFU/mL in raw milk and three ripening times (4, 22 and 60 days). Soft cheese modeling scenarios considered L. monocytogenes starting concentration from −2.4 to 4 log CFU/mL in milk. The inclusion of anti-listerial lactic acid bacteria (LAB) in cheeses was also examined. Risk of listeriosis due to consumption of soft cheese was 6000 and 190 times greater than that of semi-hard cheese, for general and vulnerable populations, respectively. Aging semi-hard cheese reduced risk, and risk was influenced by L. monocytogenes starting concentration. Aging cheese with inhibitory LAB for 22 days reduced risk over 4 million-fold when L. monocytogenes was assumed to be 6 log CFU/mL in raw milk. The inclusion of inhibitory LAB also reduced risk of listeriosis due to soft cheese consumption, but not as much as for semi-hard cheese. QMRA results predicted that consumption of contaminated cheeses can carry a high risk of listeriosis, especially for vulnerable populations. Scenario analyses indicated that aging of semi-hard cheese and inclusion of antimicrobial LAB mix in semi-hard and soft cheeses are effective risk mitigation measures. [ABSTRACT FROM AUTHOR]

Background Cooked ready-to-eat (RTE) meat products are subjected to contamination of spoilage microorganisms such as lactic acid bacteria and pathogens such as Listeria monocytogenes . These microorganisms contaminate cooked RTE meat products after the cooking step and may further grow during shelf-life potentially leading to spoilage or foodborne diseases, respectively. In the current context of salt, fat and chemical preservatives reduction in meat products formulations, a combined strategy that considers the development of more robust formulations, active packaging and the use of non-thermal post-packaging decontamination strategies seems required to ensure shelf-stable and safe RTE cooked food products. Scope and approach The main objective of this review was to discuss the aspects related to reformulation, active packaging and the application of non-thermal decontamination technologies at the post-packaging step of cooked RTE meat products, their advantages, limitations and main challenges for their implementation. Key findings and conclusions In general, post-packaging decontamination technologies aim to reduce or inactivate pathogens and spoilage microorganisms present on the surface of ready-to-eat meat products. Low-temperature plasma, high-pressure processing (HPP), pulsed electric fields, pulsed ultraviolet light and ultrasound are promising alternatives in this segment. However, the choice of the most appropriate approach for post-packaging decontamination of cooked ready-to-eat meat products depends on the type of product and the technological objectives. Meat products formulation and packaging material properties should be considered while defining a post-packaging decontamination approach. Although they are advantageous, non-thermal technologies may present certain limitations such as the increase of oxidative reactions over the shelf-life. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a predictive model for the growth of L . monocytogenes and Salmonella in the pulp and the outer rind of Canary melons ( Cucumis melo L.) as a function of temperature. The experiments of L . monocytogenes and Salmonella enterica showed that the former can grow in all temperatures tested, from 5 °C to 35 °C, both on the outer rind and in the pulp of melons while the latter did not grow when the outer rind and the pulp of Canary melons were stored at 5 °C. There was no significant difference (p > 0.05) regarding the growth kinetic parameters [growth rate (μ) and lag time (λ)] when the pathogens were inoculated on the outer rind and pulp following storage between 15 and 35 °C. Secondary models (Ratkowsky model) were able to describe the influence of temperature on μ and λ for both microorganisms on the outer rind and pulp of Canary melons. This study adds quantitative data to the literature on the fate of L . monocytogenes and S . enterica in Canary melons and reveal that pulp and the outer rind of this fruit comprise substrates that support the growth of both pathogens in a wide range of storage temperature. [ABSTRACT FROM AUTHOR]

In this study the growth potential (δ) of Listeria monocytogenes in six formulations of probiotic ( Lactobacillus acidophilus and Bifidobacterium lactis ) reduced-sodium cottage cheese containing or not NaCl, combined with KCl and/or MgCl 2 stored under different temperature conditions was assessed. Reduced-sodium cottage cheeses were inoculated with L. monocytogenes (approximately 10 3 CFU/g) and then stored at 4 °C (I), 30% of the shelf life at 4 °C and the remaining 70% at 12 °C (II) and 12 °C (III) for 28 days. A growth potential ( δ ) above 0.5 log CFU/g indicated that the formulation was capable of supporting the growth of L. monocytogenes . The growth potential ( δ ) of L. monocytogenes at 4 °C (I) was between 0.5 and 0.8 log CFU/g. Higher growth potentials (1.1–1.6 log CFU/g) were observed when the cottage cheeses were stored for 30% of the shelf life at 4 °C followed by storage for 70% at 12 °C (II). In the scenario III (28 days at 12 °C), L. monocytogenes was only able to grow in the formulation with 100% NaCl and no probiotics (F1), while in F2–F6 (probiotic formulations with different combinations of NaCl, KCl, MgCl 2 ) the populations of this bacterium were below the quantification level (< 1 log CFU/g). Independent of the storage scenarios studied, strict conditions of hygiene during processing and use of raw materials of excellent microbiological quality are key-factors for ensuring the safety of this product as L. monocytogenes will be able to grow at low storage temperature. [ABSTRACT FROM AUTHOR]

This study aimed to determine the growth potential (δ) of L. monocytogenes (CLIST 3974, CLIST 3969, and CLIST 4162) and S. enterica [ S. Typhimurium (ATCC SM 14028), S. Enteritidis (SM 64), and S. Montevideo (SM 129)] in the presence of a pool of lactic acid bacteria (LAB) with antimicrobial activity in Frescal and semi-hard Minas microcheeses. The δ was determined after storing Frescal cheese at 4 and 7 °C for 15 days and the and semi-hard Minas cheese during ripening (22 °C for 22 days). The δ of L. monocytogenes was significantly higher in Frescal Minas cheese with no added LAB (p > 0.05). On the other hand, in semi-hard cheese inoculated with LAB, inactivation of L. monocytogenes was observed. No significant differences were found in the δ of S. enterica in Frescal Minas cheese inoculated with LAB at 4 and 7 °C. S. enterica SM 14028 and SM 129 could grow in semi-hard cheeses non-inoculated with LAB, while when LAB was inoculated, S. enterica was inactivated. The findings of this study indicated that the δ of L. monocytogenes strains was more affected in cheeses inoculated with LAB than the δ of S. enterica. • Selected lactic acid bacteria (LAB) impact the Listeria growth in Minas Cheese. • LAB caused inactivation of L. monocytogenes in semi-hard cheese. • Effects of LAB on S. enterica growth varied with cheese type and strain tested. • LAB influenced the ending pH for all treatments, regardless the cheese type. [ABSTRACT FROM AUTHOR]

• Probiotic and biopreservation potential of 220 lactic acid bacteria. • Twenty-two out of 220 LAB satisfied in vitro criteria as probiotic candidates. • Technological and functional traits varied in LAB isolated from artisanal cheeses. • L. plantarum (1QB77) led up to 4 log reductions of S. aureus and L. monocytogenes in microcheeses. • Insights on indigenous LAB traits as starter cultures for tailored applications. The increasing interest in products with functional properties has encouraged the search for new lactic acid bacteria (LAB) present in natural sources, as traditional fermented foods. In this study, a large set of wild LAB isolates (n = 220) from Brazilian artisanal cheeses (BAC) were assessed for their probiotic and biopreservation potential. First, the rational selection was performed. From the tested isolates, 92 (41.8 %) were resistant to low pH (2 and 3). These isolates were submitted to bile salt (0.4 % Oxgall powder) resistance, and 22 were selected and submitted to adhesion assays. The autoaggregation values ranged from 68.5–99% and were considered moderate to high (20–70 %). Hydrophobicity values varied significantly between LAB (5.0–64.3%), and seven isolates presented values higher than 40 %. All selected LAB (n= 22) were capable of adhering to Caco-2 (> 70 %) cells, and none isolate displayed any tested gene for biogenic amine production. Most isolates (18/22) showed less than 1 log CFU reduction after passage through the simulated gastrointestinal tract (GIT) conditions. A total of twenty isolates satisfied key in vitro criteria to be considered as probiotics. A hierarchical cluster analysis (HCA) was performed, and two clusters were observed, showing high variability between Lactobacillus plantarum isolates regarding adhesion properties and survival to GIT stress and one influence of the source of isolation on these properties. After screening, the antimicrobial activity of Lb. plantarum (1QB77) was tested in microcheeses in which survival of two relevant pathogenic bacteria (Staphylococcus aureus and Listeria monocytogenes) was monitored along ripening and after a simulated GIT passage, concomitantly. L. plantarum (1QB77) has shown the ability to reach high counts (∼ 9 log CFU/g) at the end of ripening. This isolate was also able to reduce counts of S. aureus and L. monocytogenes in microcheeses in approx. 2.3 and 2.5 log CFU/g, respectively, until the 21st day of ripening; and about 3.2 and 3.5 log CFU/g after simulated GIT passage. Overall, the assessment of the probiotic properties of a large set of LAB was fundamental for gaining insights on the technological, functional, and potential regional traits of wild LAB isolates that can be used to develop starter cultures for tailored applications. [ABSTRACT FROM AUTHOR]

Traditionally fermented food generally has unique sensorial aspects due to its high microbial diversity, being broadly consumed worldwide. Despite this, some Vancomycin-Resistant-Enterococci (VRE) can occur in these products, which raises questions about their safety. Thus, this study tries to assess information about the occurrence of Enterococcus strains in traditional Brazilian cheese samples collected from the five main regions as well as the characterization of their phenotypic (proteolytic, lipolytic and bacteriogenic potential) and safety (hemolysin activity and growth at commercial VRE selecting media) aspects. A total of 1669 lactic acid bacteria were isolated, of which 605 (36.2%) were identified as Enterococcus by 16sRNA sequencing. Out of these, E. faecium (58.7%) was identified as the dominant species, followed by Enterococcus faecalis (31.8%), Enterococcus durans (4.8%), Enterococcus hermanniensis (1.6%) and Enterococcus gilvus (1.6%). All the data were analyzed by multivariate statistics, and the findings highlighted the presence of Enterococcus as a naturally component of indigenous microbiota of Brazilian artisanal cheeses, mostly in the cheeses of Marajó, Coalho, and Manteiga, possibly as a consequence of their heat resistance and the curd cooking step applied during the process in these regions. The majority of the identified Enterococcus (63.1%) did not produce β-hemolysin and were not resistant to vancomycin. Interestingly some of these strains (21.4%) were able to inhibit Listeria monocytogenes ATCC 35152, mostly isolates from Serrano, Colonial, and Minas artisanal (from Cerrado microregion) cheeses. Also, 10.2 and 11.8% of them have shown moderate to high proteolytic and lipolytic activity, respectively. Anti -listerial activity is of most interest as it can contribute to reduce risk of listeriosis due to dairy products consumption, while proteolysis and lipolysis are responsible for some remarkable features (e. g. flavor, taste, and texture) of fermented foods. In summary, this study represents a contribution towards revealing some phenotypic and safety traits of a large set of strains of Enterococcus strains through the use of multivariate statistics combined with high throughput tools. • Large sampling (n = 582) to assess Enterococcus in Brazilian artisanal cheese (BAC). • Total of 1669 lactic acid bacteria isolated and 605 (36.2%) were Enterococcus. • High throughput tools used to assess phenotypic and safety Enterococcus properties. • 63.1% of Enterococcus did not produce β-hemolysin and were sensible to vancomycin. • Multivariate statistics allowed the link between Enterococcus properties BAC types. [ABSTRACT FROM AUTHOR]

The inactivation kinetics of Listeria monocytogenes in whey dairy beverage submitted to ohmic heating processing (OH, 3 V/cm, 57.5–60 °C for 38-4 min) was investigated. Besides, the physicochemical characterization and sensory analysis of the whey dairy beverage processed by OH were performed. OH at 65 °C resulted in a reduction rate (RR) of 2.10 log CFU/mL−1min−1 while conventional processing (CP) resulted in RR of 1.38 log CFU/mL−1min−1 of Listeria monocytogenes. Concerning the physicochemical parameters, OH-treated beverages presented lower pH and hydroxymethylfurfural values and improved sensory scores, despite the lower brightness observed in the color measurements. Overall, OH is an interesting technology to be used in whey dairy beverage processing. The results of this study comprise key and useful data for application in quantitative risk models to estimate the risk of listeriosis due to the consumption of whey dairy beverages. • Inactivation kinetics of Listeria monocytogenes in whey dairy beverage submitted to ohmic heating. • Decreased pH and hydroxymethylfurfural values. • Improved sensory scored at the consumer test. [ABSTRACT FROM AUTHOR]