Listeria monocytogenes inhibition by lactic acid bacteria and coliforms in Brazilian fresh white cheese.

INTRODUCTION: Minas fresh cheese (MFC), a Brazilian white cheese, is one of the most popular cheeses nationwide. Studies have shown that Listeria monocytogenes occurrence in this product is generally low, while high populations of coliforms can be found. This study aimed to evaluate the influence of coliforms in the behavior of L. monocytogenes in MFC. METHODS: Pasteurized milk was inoculated with L. monocytogenes and coliforms, and the acidification was made by lactic acid or by the addition of a starter culture. The cheeses of each production were divided into 3 groups and stored at 5 ºC, 12 ºC and cycles of 5 ºC followed by 25 ºC. In predetermined days, samples were taken and L. monocytogenes, coliforms and lactic acid bacteria populations were evaluated, besides the pH, water activity (aw), titratable acidity and NaCl concentration. RESULTS: The inhibition of L. monocytogenes in the presence of coliforms was observed (p < 0.05), except for those samples prepared with lactic acid and stored at temperature cycles. The values of pH and aw were not sufficiently low to cause inhibition; however, titratable acidity was higher in cheeses containing coliforms. In vitro tests containing lactic acid and L. monocytogenes showed that the bacterium is sensitive to concentration of lactic acid ≥ 0.3%, indicating that lactic acid produced by coliforms strongly influences the population of L. monocytogenes. CONCLUSIONS: Thus, it can be concluded that coliforms negatively impact populations of L. monocytogenes in MFC. We strongly recommend that producers of MFC adopt good hygiene practices to not only avoid contamination with L. monocytogenes, but also coliforms.

Sobrevivência e desenvolvimento de Pseudomonas aeruginosa em água mineral experimentalmente contaminada / Survival and growth of Pseudomonas aeruginosain experimentally contaminated mineral water

Pseudomonas aeruginosa, agente patogênico oportunista, é frequentemente encontrado em águas minerais e pode causar infecções em indivíduos imunocomprometidos. Neste estudo foi avaliada a sobrevivência e/ou a multiplicação de P. aeruginosa em amostras de água mineral em embalagens plásticas de 1,5 L e 20 L, experimentalmente contaminadas, armazenadas a 35 ± 1ºC, 4 ± 2°C e em temperatura ambiente (20-25ºC), durante o período de validade do produto. Nas amostras de água mineral em garrafa plástica de 1,5 L, armazenadas a 35 ± 1ºC e 4 ± 2ºC, a população de P. aeruginosamanteve-se viável durante 370 e 100 dias, respectivamente. O maior aumento da população bacteriana ocorreu nas amostras de água mineral em galão de 20 L, armazenadas entre 20 a 25ºC, que passou de 3,8 para 6,6 log10 UFC/mL em um período de sete dias. Portanto, os galões de 20 L merecem atenção especial, pois além de serem retornáveis, normalmente são armazenados à temperatura ambiente. Os resultados reforçam a necessidade das empresas de águas minerais implantarem e implementarem as Boas Práticas de Fabricação (BPF) e o sistema Análise de Perigo e Pontos Críticos de Controle (APPCC) para eliminar ou minimizar os riscos do consumo deste produto. (AU)

Pseudomonas aeruginosa, an opportunistic pathogen, is often found in bottled waters and capable of infecting the immunocompromised patients. The present study aimed at evaluating the survival and/or the growth of P. aeruginosa strain in 1,5 L and 20 L bottled mineral water samples experimentally contaminated, stored at 35 ± 1°C, 4 ± 2°C, and at room temperature (from 20 to 25°C) during the product shelf-life period. In the mineral water samples contained in 1.5 L bottles, stored at 35 ± 1ºC and 4 ± 2ºC, P. aeruginosa remained viable for 370 and 100 days, respectively. The major increase in the bacterial population occurred in mineral water samples in 20 L bottles stored at 20 to 25ºC, being from 3.8 to 6.6 log10 CFU/mL, in a period of seven days. Therefore, the 20 L bottles deserve a special attention because, in addition of being returnable, they are usually stored at room temperature. The results reinforce the need of the mineral water companies in implementing the Good Manufacturing Practice (GMP) and the HACCP (Hazard Analysis Critical Control Point) to eliminate and to minimize the risks of consuming the contaminated product. (AU)

Sobrevivência e desenvolvimento de Pseudomonas aeruginosa em água mineral experimentalmente contaminada / Survival and growth of Pseudomonas aeruginosa in experimentally contaminated mineral water

Pseudomonas aeruginosa, agente patogênico oportunista, é frequentemente encontrado em águas minerais e pode causar infecções em indivíduos imunocomprometidos. Neste estudo foi avaliada a sobrevivência e/ou a multiplicação de P. aeruginosa em amostras de água mineral em embalagens plásticas de 1,5 L e 20 L, experimentalmente contaminadas, armazenadas a 35 ± 1ºC, 4 ± 2°C e em temperatura ambiente (20-25ºC), durante o período de validade do produto. Nas amostras de água mineral em garrafa plástica de 1,5 L, armazenadas a 35 ± 1ºC e 4 ± 2ºC, a população de P. aeruginosa manteve-se viável durante 370 e 100 dias, respectivamente. O maior aumento da população bacteriana ocorreu nas amostras de água mineral em galão de 20 L, armazenadas entre 20 a 25ºC, que passou de 3,8 para 6,6 log10 UFC/mL em um período de sete dias. Portanto, os galões de 20 L merecem atenção especial, pois além de serem retornáveis, normalmente são armazenados à temperatura ambiente. Os resultados reforçam a necessidade das empresas de águas minerais implantarem e implementarem as Boas Práticas de Fabricação (BPF) e o sistema Análise de Perigo e Pontos Críticos de Controle (APPCC) para eliminar ou minimizar os riscos do consumo deste produto.

Pseudomonas aeruginosa, an opportunistic pathogen, is often found in bottled waters and capable of infecting the immunocompromised patients. The present study aimed at evaluating the survival and/ or the growth of P. aeruginosa strain in 1,5 L and 20 L bottled mineral water samples experimentally contaminated, stored at 35 ± 1°C, 4 ± 2°C, and at room temperature (from 20 to 25°C) during the product shelf-life period. In the mineral water samples contained in 1.5 L bottles, stored at 35 ± 1ºC and 4 ± 2ºC, P. aeruginosa remained viable for 370 and 100 days, respectively. The major increase in the bacterial population occurred in mineral water samples in 20 L bottles stored at 20 to 25ºC, being from 3.8 to 6.6 log10 CFU/mL, in a period of seven days. Therefore, the 20 L bottles deserve a special attention because, in addition of being returnable, they are usually stored at room temperature. The results reinforce the need of the mineral water companies in implementing the Good Manufacturing Practice (GMP) and the HACCP (Hazard Analysis Critical Control Point) to eliminate and to minimize the risks of consuming the contaminated product.

Assessment of Consumer Exposure to Salmonella spp., Campylobacter spp., and Shiga Toxin-Producing Escherichia coli in Meat Products at Retail in the City of Sao Paulo, Brazil.

Meat products may be vehicles of bacterial pathogens to humans, and Salmonella spp., Campylobacter spp., and Shiga toxin-producing Escherichia coli (STEC) are the most relevant. The aim of this study was to generate data on prevalence of these three pathogens in 552 samples of meat products (hot dogs, pork sausages, raw ground beef, and raw chicken legs) sold at retail in the city of Sao Paulo, Brazil. Salmonella spp. was detected in 5.8% (32/552) of samples, comprising pork sausages 62.5% (20/32) and chicken legs 37.5% (12/32). The counts of Salmonella spp. were low, ranging from < 0.3 to 9.3 × 10 most probable number per gram and the most frequent serovars were Salmonella Typhimurium (28.1%), Salmonella I 4,[5],12:i:- (15.6%), Salmonella Enteritidis (12.5%), Salmonella Derby, and Salmonella Brandenburg (9.4%). Campylobacter spp. was detected in 33 samples (6.0%), comprising chicken legs (82%) and ground beef (18%). All samples were negative for STEC. These results suggest that meat products when subjected to inadequate cooking and/or cross-contamination with other products ready for consumption can lead to occurrence of outbreaks, highlighting the risks associated with them.

Prevalence and populations of Listeria monocytogenes in meat products retailed in Sao Paulo, Brazil.

This study evaluated the prevalence of the populations and serotypes of Listeria monocytogenes in 552 refrigerated samples of ground beef, chicken leg, hot dog, and pork sausage collected in supermarkets in the city of Sao Paulo, SP, Brazil, between May 2008 and July 2009. The supermarkets were selected after stratification by geographical region and by random draw. Tests for presence and enumeration of L. monocytogenes were based on ISO 11290-1:1996/Amd.1:2004 and ISO 11290-2:1998 methods, respectively. Listeria spp. were detected in 469 (85.0%) of the studied meat products. The most frequently isolated species was L. innocua (64.1%), followed by L. monocytogenes (48.7%), L. welshimeri (13.4%), L. seeligeri (7.1%), L. ivanovii (0.2%), and L. grayi subspecies murrayi (0.2%). L. monocytogenes was detected in 269 (48.7%) samples, with highest prevalence in ground beef (59.4%) followed by chicken legs (58.0%), pork sausages (39.8%), and hot dogs (37.7%). The populations were <10(2) colony-forming units/g in the majority of samples (62.5%). Prevalence of serotypes varied according to the type of meat product. These data are relevant for estimating the risks of listeriosis associated with consumption of meat products in Sao Paulo, and for establishing science-based intervention strategies aimed at reducing these risks, especially for pregnant women and immunocompromised individuals.

Changes in total ascorbic acid and carotenoids in minimally processed irradiated Arugula (Eruca sativa Mill) stored under refrigeration

This work investigated the effects of irradiation (0, 1 and 2 kGy) on the content of bioactive compounds such as vitamin C and carotenoids with provitamin A activity in arugula during the storage at 571 1C for up to 13 and 16 days, respectively. The vitamin C content decreased in non-irradiated as well as irradiated (1 and 2 kGy) samples during the storage period. On the other hand, no significant change in the content of carotenoids with provitamin...(AU)

Efeitos da radiação gama na microbiota e no teor de vitamina C de agrião (Nasturtium officinale) orgânico minimamente processado: aceitação e intenção de compra do produto irradiado / Effects of gamma irradiation in microbiota and of vitamin C of organic watercress (Nasturtium officinale) minimally processed: acceptance an intention of irradiated produce

O aumento do consumo de vegetais frescos e a globalização do mercado de hortaliças e frutas frescas provocaram um aumento na preocupação com as enfermidades transmitidas por alimentos (ETA) associadas a esses produtos. No Brasil, a produção de hortaliças orgânicas vem crescendo, aproximadamente 40 ’POR CENTO’ ao ano. Considerando o exposto, foram analisadas 108 amostras de agrião orgânico minimamente processado e irradiado coletadas, aleatoriamente, em produtores da região de São Roque, São Paulo, no período de novembro de 2005 a março de 2007, para avaliar a ecologia microbiana e a concentração de vitamina C ao longo da cadeia produtiva. As amostras de agrião orgânico coletadas no campo e as de minimamente processado apresentaram populações superiores a 3,0 log UFC/g para aeróbios mesófilos, aeróbios psicrotróficos, Pseudomonas spp, coliformes termotolerantes e E. coli. Salmonella spp, E. coli 0157:H7 e L. monocytogenes não foram detectadas ao longo da cadeia produtiva...

Minimally processed vegetable salads: microbial quality evaluation.

The increasing demand for fresh fruits and vegetables and for convenience foods is causing an expansion of the market share for minimally processed vegetables. Among the more common pathogenic microorganisms that can be transmitted to humans by these products are Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella. The aim of this study was to evaluate the microbial quality of a selection of minimally processed vegetables. A total of 181 samples of minimally processed leafy salads were collected from retailers in the city of Sao Paulo, Brazil. Counts of total coliforms, fecal coliforms, Enterobacteriaceae, psychrotrophic microorganisms, and Salmonella were conducted for 133 samples. L. monocytogenes was assessed in 181 samples using the BAX System and by plating the enrichment broth onto Palcam and Oxford agars. Suspected Listeria colonies were submitted to classical biochemical tests. Populations of psychrotrophic microorganisms >10(6) CFU/g were found in 51% of the 133 samples, and Enterobacteriaceae populations between 10(5) and 106 CFU/g were found in 42% of the samples. Fecal coliform concentrations higher than 10(2) CFU/g (Brazilian standard) were found in 97 (73%) of the samples, and Salmonella was detected in 4 (3%) of the samples. Two of the Salmonella-positive samples had <10(2) CFU/g concentrations of fecal coliforms. L. monocytogenes was detected in only 1 (0.6%) of the 181 samples examined. This positive sample was simultaneously detected by both methods. The other Listeria species identified by plating were L. welshimeri (one sample of curly lettuce) and L. innocua (2 samples of watercress). The results indicate that minimally processed vegetables had poor microbiological quality, and these products could be a vehicle for pathogens such as Salmonella and L. monocytogenes.