Isolation, characterization, and application of bacteriophage cocktails for the biocontrol of Pseudomonas fluorescens group strains in whole and skimmed milk.

Pseudomonas fluorescens group strains can lead to spoilage of milk as well as loss of quality in dairy products through their heat-resistant enzymes. Phages are important alternatives for combating spoilage bacteria in food industry and used successfully in many applications. The aim of this study was the isolation and characterization of phages and to assess the efficiency of a phage cocktail in whole and skimmed milk. For this purpose, phages effective against Pseudomonas fluorescens (L23.2), Pseudomonas tolaasii (P22.1), and Pseudomonas rhodesiae (A11.1) were isolated. Their host range was found to be highly specific, and the transmission electron micrographs indicates that they belonged to Tectiviridae family. Their genome sizes were found to be vary between 38.3 and 53.5 kb. The latent periods and burst sizes were determined as 15, 10, 15 min and 91, 20, 80 PFU/infected cell for L23.2, P22.1, and A11.1, respectively. All three phages were found to be sensitive to low pH and high temperature. The effect of the phage cocktail was monitored in milk with different fat contents during storage at 4 °C for 5 days. As a result, bacterial reductions up to 4.09 and 5.29 log-units were observed for the whole and skimmed milk, respectively. Thus, the efficacy of a phage cocktail against a bacterial mixture of different P. fluorescens strains was tested in milk samples with different fat contents in accordance with real-life scenarios for the first time.

Lytic bacteriophages UFJF_PfDIW6 and UFJF_PfSW6 prevent Pseudomonas fluorescens growth in vitro and the proteolytic-caused spoilage of raw milk during chilled storage.

In this study, P. fluorescens-infecting phages were isolated, characterized, and evaluated to their potential to control the bacterial counts and, consequently, the proteolytic spoilage of raw milk during cold storage. The UFJF_PfDIW6 and UFJF_PfSW6 phages showed titers of 9.7 and 7.6 log PFU/ml; latent period of 115 and 25 min, and burst size of 145 and 25 PFU/infected cell, respectively. They also were highly specific to the host bacterium, morphologically classified as the Podoviridae family, stable at pH 5 to 11 and were not inactivated at 63 °C or 72 °C for 30 min. These phages found to be effective against P. fluorescens, reducing bacterial count throughout the entire exponential growth phase in broth formulated with milk at both 4 °C and 10 °C. This effect on bacteria growth led to inhibition by at least 2 days in proteases production, delaying the degradation of milk proteins. When applied together in raw milk stored at 4 °C, they reduced the total bacteria, psychrotrophic, and Pseudomonas by 3 log CFU/ml. This study's findings indicate that these phages have a great potential to prevent the growth of Pseudomonas and, consequently, to retard proteolytic spoilage of raw milk during chilled storage.

Multiplicação microbiana no leite cru armazenado em tanques de expansão direta / Microbial multiplication in raw milk stored in direct expansion bulk tanks

O presente estudo objetivou avaliar o efeito do tempo de armazenagem do leite em tanques de expansão direta, modelo de duas e quatro ordenhas, sobre a contagem bacteriana total (CBT) e a contagem de bactérias psicrotróficas (CBP). As avaliações foram conduzidas em 19 propriedades leiteiras, localizadas nas regiões Serrana e Oeste de Santa Catarina, as quais utilizavam equipamentos de refrigeração do leite por expansão direta, modelo de duas ou quatro ordenhas, com taxa de ocupação variando de 60 a 100% de sua capacidade. Antes e após cada ordenha, foram coletadas amostras de leite para análise de CBT, CBP e contagem de células somáticas (CCS), totalizando aproximadamente 36 horas de armazenagem (quatro ordenhas). O tempo de armazenagem do leite cru resfriado não afetou a CBT e CBP (P>0,05) em ambos os modelos. O modelo de tanque de expansão afetou somente a CBP (P<0,05), com média inferior para amostras de leite de tanques de duas ordenhas em relação ao de quatro ordenhas (3,61±0,104 e 4,00±0,120UFC mL-1 (log10), respectivamente). Conclui-se que tanques de resfriamento por expansão direta, utilizados dentro de suas especificações quanto ao volume de leite a ser resfriado, permitem a manutenção da CBT e da CBP em sistemas de transporte do leite ao laticínio a cada 48 horas.(AU)

The purpose of this study was to evaluate the effect of the cold storage period of raw milk in bulk tanks, using two and four milking models, on total bacterial count (TBC) and psychrotrophic bacterial count (PBC). A total of 19 dairy farms, located in West and Uplands of the Santa Catarina State - Brazil, was been evaluated. Each dairy farm had direct expansion bulk milk tank and an occupancy rate varying from 60% to 100%. Samples were collected before and after each milking procedure to determine PBC and TBC, totalizing four milking and a storage period of 36 hours. The storage time did not affect TBC and PBC (P>0.05). The bulk tank model only affected the PBC (P < 0.05), with two-milking model presenting a lower mean than four-milking model (3.61±0.104 and 4.00±0.120CFU mL-1 (log10)). It was possible to conclude that bulk tanks, when used properly concerning raw milk volume to be chilled, allow the TBC and PBC to remain stable in the transportation systems of raw milk to the industry each 48 hours.(AU)

Multiplicação microbiana no leite cru armazenado em tanques de expansão direta / Microbial multiplication in raw milk stored in direct expansion bulk tanks

O presente estudo objetivou avaliar o efeito do tempo de armazenagem do leite em tanques de expansão direta, modelo de duas e quatro ordenhas, sobre a contagem bacteriana total (CBT) e a contagem de bactérias psicrotróficas (CBP). As avaliações foram conduzidas em 19 propriedades leiteiras, localizadas nas regiões Serrana e Oeste de Santa Catarina, as quais utilizavam equipamentos de refrigeração do leite por expansão direta, modelo de duas ou quatro ordenhas, com taxa de ocupação variando de 60 a 100% de sua capacidade. Antes e após cada ordenha, foram coletadas amostras de leite para análise de CBT, CBP e contagem de células somáticas (CCS), totalizando aproximadamente 36 horas de armazenagem (quatro ordenhas). O tempo de armazenagem do leite cru resfriado não afetou a CBT e CBP (P>0,05) em ambos os modelos. O modelo de tanque de expansão afetou somente a CBP (P<0,05), com média inferior para amostras de leite de tanques de duas ordenhas em relação ao de quatro ordenhas (3,61±0,104 e 4,00±0,120UFC mL-1 (log10), respectivamente). Conclui-se que tanques de resfriamento por expansão direta, utilizados dentro de suas especificações quanto ao volume de leite a ser resfriado, permitem a manutenção da CBT e da CBP em sistemas de transporte do leite ao laticínio a cada 48 horas.

The purpose of this study was to evaluate the effect of the cold storage period of raw milk in bulk tanks, using two and four milking models, on total bacterial count (TBC) and psychrotrophic bacterial count (PBC). A total of 19 dairy farms, located in West and Uplands of the Santa Catarina State - Brazil, was been evaluated. Each dairy farm had direct expansion bulk milk tank and an occupancy rate varying from 60% to 100%. Samples were collected before and after each milking procedure to determine PBC and TBC, totalizing four milking and a storage period of 36 hours. The storage time did not affect TBC and PBC (P>0.05). The bulk tank model only affected the PBC (P < 0.05), with two-milking model presenting a lower mean than four-milking model (3.61±0.104 and 4.00±0.120CFU mL-1 (log10)). It was possible to conclude that bulk tanks, when used properly concerning raw milk volume to be chilled, allow the TBC and PBC to remain stable in the transportation systems of raw milk to the industry each 48 hours.

Detection of airborne psychrotrophic bacteria and fungi in food storage refrigerators

The purpose of this study was to determine the microbiological air quality (psychrotrophic bacteria and airborne fungi) and distribution of fungi in different types of ready-to-eat (RTE) food-storage refrigerators (n=48) at selected retail stores in the city of Edirne, Turkey. Refrigerators were categorized according to the type of RTE food-storage: meat products, vegetables, desserts, or a mix of food types. Microbiological quality of air samples was evaluated by using a Mas-100 Eco Air Sampler. Four refrigerators (all containing meat products, 8.3%) produced air samples with undetectable microorganisms. The highest detected mean value of airborne psychrotrophic bacteria and fungi was 82.3 CFU/m³ and 54.6 CFU/m³, respectively and were found in mixed-food refrigerators. The dominant airborne fungal genera found were Penicillium (29.0%), Aspergillus (12.0%), Mucor (9%), Cladosporium (8%), Botyrtis (7%), and Acremonium (6%). By definition, RTE food does not undergo a final treatment to ensure its safety prior to consumption. Therefore, ensuring a clean storage environment for these foods is important to prevent food-borne disease and other health risks.(AU)

Detection of airborne psychrotrophic bacteria and fungi in food storage refrigerators

The purpose of this study was to determine the microbiological air quality (psychrotrophic bacteria and airborne fungi) and distribution of fungi in different types of ready-to-eat (RTE) food-storage refrigerators (n=48) at selected retail stores in the city of Edirne, Turkey. Refrigerators were categorized according to the type of RTE food-storage: meat products, vegetables, desserts, or a mix of food types. Microbiological quality of air samples was evaluated by using a Mas-100 Eco Air Sampler. Four refrigerators (all containing meat products, 8.3%) produced air samples with undetectable microorganisms. The highest detected mean value of airborne psychrotrophic bacteria and fungi was 82.3 CFU/m³ and 54.6 CFU/m³, respectively and were found in mixed-food refrigerators. The dominant airborne fungal genera found were Penicillium (29.0%), Aspergillus (12.0%), Mucor (9%), Cladosporium (8%), Botyrtis (7%), and Acremonium (6%). By definition, RTE food does not undergo a final treatment to ensure its safety prior to consumption. Therefore, ensuring a clean storage environment for these foods is important to prevent food-borne disease and other health risks.

Association between milking practices and psychrotrophic bacterial counts in bulk tank milk / Asociación entre prácticas de ordeño y recuento de organismos psicrótrofos en leche de tanque de frío

The objective of this work was to determine on-farm risk factors for psychrotrophic bacterial counts in bulk tank milk from dairy farms in Argentina. Raw milk samples from bulk tanks of 27 dairy farms were examined for total psychrotrophic counts (TPC), proteolytic psychrotrophic counts (PPC) and lipolytic psychrotrophic counts (LPC) (dependent or outcome variables). A survey recording infrastructure conditions, milking equipment and milking management (independent variables) was performed. Bivariate association proofs and logistic regression analyses were used to determine association between independent variables and psychrotrophic bacterial counts. Milk cooled in plate heat exchangers or barrel tanks were 16.39 and 10.52 times more likely to yield TPC and PPC above the standard established for high quality milk compared with milk cooled in bulk tanks, respectively. Periodic cleaning of cooling tanks (3 times a week or daily) was associated with lower TPC (approximately 1.5 log CFU/ml) than weekly cleaning frequency and farms where milkers did not wash their hands during milking time were 7.81 times more likely to have higher PPC. No association was found between LPC and any of the independent variables. The only variable associated with TPC and PPC in a logistic regression model was the refrigeration system used on the farm. Dairy farms that possessed bulk milk cooling tanks yielded the lowest bacterial counts. Results of this study highlight the importance of both the type of cooling system used on the farm and its adequate hygienic maintenance for obtaining low pshychrotrophic counts at dairy farm.(AU)

El objetivo del trabajo fue determinar los factores de riesgo para altos recuentos de organismos psicrótrofos en leche de tanques de tambos de la Argentina. Se examinaron muestras de leche cruda de tanques de frío de 27 tambos, y se realizó el recuento de organismos psicrótrofos totales (PT), de psicrótrofos proteolíticos (PP) y de psicrótrofos lipolíticos (PL) (variables dependientes). Se realizó una encuesta para registrar las condiciones de infraestructura, el equipo de ordeño y las prácticas de ordeño (variables independientes). Se utilizaron pruebas bivariadas de asociación y regresión logística para determinar la asociación entre las variables independientes y los recuentos de organismos psicrótrofos. La leche enfriada en sistemas de placas de intercambio o tanques tipo cuba tuvo una probabilidad mayor de dar recuentos elevados de PT y PP (16,39 y 10,52) comparada con la enfriada en tanques tipo "panza fría". La limpieza periódica del equipo de frío (3 veces por semana o diariamente) se asoció con bajos recuentos de PT (aproximadamente 1,5 log de UFC/ml). Los tambos cuyos ordeñadores no se higienizaban las manos durante el ordeño tuvieron una probabilidad 7,81 veces mayor de tener recuentos elevados de PP. No se encontró asociación entre el recuento de PL y las variables independientes. La única variable asociada con los recuentos de PT y PP en el modelo de regresión logística fue el sistema de enfriamiento utilizado en el tambo. El tipo de sistema de refrigeración usado y su adecuado mantenimiento higiénico son importantes para la obtención de leche con baja carga de organismos psicrótrofos en el tambo.(AU)

Association between milking practices and psychrotrophic bacterial counts in bulk tank milk / Asociación entre prácticas de ordeño y recuento de organismos psicrótrofos en leche de tanque de frío

The objective of this work was to determine on-farm risk factors for psychrotrophic bacterial counts in bulk tank milk from dairy farms in Argentina. Raw milk samples from bulk tanks of 27 dairy farms were examined for total psychrotrophic counts (TPC), proteolytic psychrotrophic counts (PPC) and lipolytic psychrotrophic counts (LPC) (dependent or outcome variables). A survey recording infrastructure conditions, milking equipment and milking management (independent variables) was performed. Bivariate association proofs and logistic regression analyses were used to determine association between independent variables and psychrotrophic bacterial counts. Milk cooled in plate heat exchangers or barrel tanks were 16.39 and 10.52 times more likely to yield TPC and PPC above the standard established for high quality milk compared with milk cooled in bulk tanks, respectively. Periodic cleaning of cooling tanks (3 times a week or daily) was associated with lower TPC (approximately 1.5 log CFU/ml) than weekly cleaning frequency and farms where milkers did not wash their hands during milking time were 7.81 times more likely to have higher PPC. No association was found between LPC and any of the independent variables. The only variable associated with TPC and PPC in a logistic regression model was the refrigeration system used on the farm. Dairy farms that possessed bulk milk cooling tanks yielded the lowest bacterial counts. Results of this study highlight the importance of both the type of cooling system used on the farm and its adequate hygienic maintenance for obtaining low pshychrotrophic counts at dairy farm.

El objetivo del trabajo fue determinar los factores de riesgo para altos recuentos de organismos psicrótrofos en leche de tanques de tambos de la Argentina. Se examinaron muestras de leche cruda de tanques de frío de 27 tambos, y se realizó el recuento de organismos psicrótrofos totales (PT), de psicrótrofos proteolíticos (PP) y de psicrótrofos lipolíticos (PL) (variables dependientes). Se realizó una encuesta para registrar las condiciones de infraestructura, el equipo de ordeño y las prácticas de ordeño (variables independientes). Se utilizaron pruebas bivariadas de asociación y regresión logística para determinar la asociación entre las variables independientes y los recuentos de organismos psicrótrofos. La leche enfriada en sistemas de placas de intercambio o tanques tipo cuba tuvo una probabilidad mayor de dar recuentos elevados de PT y PP (16,39 y 10,52) comparada con la enfriada en tanques tipo "panza fría". La limpieza periódica del equipo de frío (3 veces por semana o diariamente) se asoció con bajos recuentos de PT (aproximadamente 1,5 log de UFC/ml). Los tambos cuyos ordeñadores no se higienizaban las manos durante el ordeño tuvieron una probabilidad 7,81 veces mayor de tener recuentos elevados de PP. No se encontró asociación entre el recuento de PL y las variables independientes. La única variable asociada con los recuentos de PT y PP en el modelo de regresión logística fue el sistema de enfriamiento utilizado en el tambo. El tipo de sistema de refrigeración usado y su adecuado mantenimiento higiénico son importantes para la obtención de leche con baja carga de organismos psicrótrofos en el tambo.

Detection of airborne psychrotrophic bacteria and fungi in food storage refrigerators.

The purpose of this study was to determine the microbiological air quality (psychrotrophic bacteria and airborne fungi) and distribution of fungi in different types of ready-to-eat (RTE) food-storage refrigerators (n=48) at selected retail stores in the city of Edirne, Turkey. Refrigerators were categorized according to the type of RTE food-storage: meat products, vegetables, desserts, or a mix of food types. Microbiological quality of air samples was evaluated by using a Mas-100 Eco Air Sampler. Four refrigerators (all containing meat products, 8.3%) produced air samples with undetectable microorganisms. The highest detected mean value of airborne psychrotrophic bacteria and fungi was 82.3 CFU/m(3) and 54.6 CFU/m(3), respectively and were found in mixed-food refrigerators. The dominant airborne fungal genera found were Penicillium (29.0%), Aspergillus (12.0%), Mucor (9%), Cladosporium (8%), Botyrtis (7%), and Acremonium (6%). By definition, RTE food does not undergo a final treatment to ensure its safety prior to consumption. Therefore, ensuring a clean storage environment for these foods is important to prevent food-borne disease and other health risks.

Avaliação microbiológica e físico-química de linguíça toscona no município de Mossoró, RN / Microbiological and physico-chemical evaluation of toscana sausage in the city of Mossoró, state of Rio Grande do Norte, Brazil

Com o objetivo de avaliar a qualidade microbiológica e físico-química da linguiça toscana comercializada no Município de Mossoró, RN, foram analisadas 28 amostras de seis supermercados, verificando-se o Número Mais Provável (NMP) de coliformes termotolerantes, Salmonella spp. e bactérias psicrotróficas, umidade, pH e atividade de água. Todas as amostras estavam dentro do padrão vigente que estabelece um limite máximo de 5 x 103 NMP/g-1 para coliformes termotole-rantes conforme a ANVISA. Na contagem de bactérias psicrotróficas houve uma variação de 2,9 x 101 a 1,31 x 104 UFC/g-1. Das 28 amostras pesquisadas quanto a presença de Salmonella spp., em cinco verificou-se a presença deste micro-organismo em 25 g. Para umidade, todas as amostras encontravam-se dentro da legislação estabelecida (< 70%) e para atividade de água os limites variaram de 0,772 a 0,809. Os valores de pH das amostras estavam entre 5,7 e 6,2. Apesar das amostras analisadas estarem dentro do estabelecido pela legislação brasileira, faz necessária a aplicação de boas práticas, visto que a contaminação por micro-organismos psicrotróficos e Salmonella foi significativa, podendo diminuir a vida de prateleira do produto e causar danos a saúde pública.(AU)

Aiming to evaluate the microbiological and physico-chemical quality of the toscana sausage commercialized in the city of Mossoró, state of Rio Grande do Norte, Brazil, samples from 6 supermarkets were analyzed, verifying the most likely number (MLN) of thermotolerant coliforms, Salmonella spp., and psychrotrophic bacteria, humidity, pH and water activity. All the samples were within the current standards which establish a maximum limit of 5 x 103 MLN/g for thermotolerant coliforms according to ANVISA. On the psychrotrophic bacteria count there was a variation of 1.46 to 4.10 expressed in log10 values. Of the 28 samples analyzed for the presence of Salmonella spp., in 5 the presence of this microorganism was verified in 25 g. In regard to humidity, all the samples were found to be in accordance with the established legislation (lower than 70% humidity), and for water activity the limits varied between 0.772 and 0.809. The pH values were within normalcy, ranging from 5.7 to 6.2. In spite of the fact that the analyzed samples are in accordance with Brazilian laws, it is necessary to apply good practices, since the contamination by psychrotrophic microorganisms and Salmonella was significant and could harm the public health and reduce the products shelf life.(AU)

Avaliação microbiológica e físico-química de linguiça toscana no Município de Mossoró, RN

Aiming to evaluate the microbiological and physico-chemical quality of the toscana sausage commercialized in the city of Mossoró, state of Rio Grande do Norte, Brazil, samples from 6 supermarkets were analyzed, verifying the most likely number (MLN) of thermotolerant coliforms, Salmonella spp. , and psychrotrophic bacteria, humidity, pH and water activity. All the samples were within the current standards which establish a maximum limit of 5 x 10³ MLN/g for thermotolerant coliforms according to ANVISA. On the psychrotrophic bacteria count there was a variation of 1.46 to 4.10 expressed in log10 values. Of the 28 samples analyzed for the presence of Salmonella spp. , in 5 the presence of this microorganism was verified in 25 g. In regard to humidity, all the samples were found to be in accordance with the established legislation (lower than 70% humidity), and for water activity the limits varied between 0.772 and 0.809. The pH values were within normalcy, ranging from 5.7 to 6.2. In spite of the fact that the analyzed samples are in accordance with Brazilian laws, it is necessary to apply good practices, since the contamination by psychrotrophic microorganisms and Salmonella was significant and could harm the public health and reduce the product's shelf life.

Com o objetivo de avaliar a qualidade microbiológica e físico-química da linguiça toscana comercializada no Município de Mossoró, RN, foram analisadas 28 amostras de seis supermercados, verificando-se o Número Mais Provável (NMP) de coliformes termotolerantes, Salmonella spp. e bactérias psicrotróficas, umidade, pH e atividade de água. Todas as amostras estavam dentro do padrão vigente que estabelece um limite máximo de 5 x 10³ NMP/g-1 para coliformes termotole-rantes conforme a ANVISA. Na contagem de bactérias psicrotróficas houve uma variação de 2,9 x 10¹ a 1,31 x 10(4) UFC/g-1. Das 28 amostras pesquisadas quanto a presença de Salmonella spp., em cinco verificou-se a presença deste micro-organismo em 25 g. Para umidade, todas as amostras encontravam-se dentro da legislação estabelecida ( 70%) e para atividade de água os limites variaram de 0,772 a 0,809. Os valores de pH das amostras estavam entre 5,7 e 6,2. Apesar das amostras analisadas estarem dentro do estabelecido pela legislação brasileira, faz necessária a aplicação de boas práticas, visto que a contaminação por micro-organismos psicrotróficos e Salmonella foi significativa, podendo diminuir a vida de prateleira do produto e causar danos a saúde pública.

Avaliação microbiológica e físico-química de linguíça toscona no município de Mossoró, RN / Microbiological and physico-chemical evaluation of toscana sausage in the city of Mossoró, state of Rio Grande do Norte, Brazil

Com o objetivo de avaliar a qualidade microbiológica e físico-química da linguiça toscana comercializada no Município de Mossoró, RN, foram analisadas 28 amostras de seis supermercados, verificando-se o Número Mais Provável (NMP) de coliformes termotolerantes, Salmonella spp. e bactérias psicrotróficas, umidade, pH e atividade de água. Todas as amostras estavam dentro do padrão vigente que estabelece um limite máximo de 5 x 103 NMP/g-1 para coliformes termotole-rantes conforme a ANVISA. Na contagem de bactérias psicrotróficas houve uma variação de 2,9 x 101 a 1,31 x 104 UFC/g-1. Das 28 amostras pesquisadas quanto a presença de Salmonella spp., em cinco verificou-se a presença deste micro-organismo em 25 g. Para umidade, todas as amostras encontravam-se dentro da legislação estabelecida (< 70%) e para atividade de água os limites variaram de 0,772 a 0,809. Os valores de pH das amostras estavam entre 5,7 e 6,2. Apesar das amostras analisadas estarem dentro do estabelecido pela legislação brasileira, faz necessária a aplicação de boas práticas, visto que a contaminação por micro-organismos psicrotróficos e Salmonella foi significativa, podendo diminuir a vida de prateleira do produto e causar danos a saúde pública.

Aiming to evaluate the microbiological and physico-chemical quality of the toscana sausage commercialized in the city of Mossoró, state of Rio Grande do Norte, Brazil, samples from 6 supermarkets were analyzed, verifying the most likely number (MLN) of thermotolerant coliforms, Salmonella spp., and psychrotrophic bacteria, humidity, pH and water activity. All the samples were within the current standards which establish a maximum limit of 5 x 103 MLN/g for thermotolerant coliforms according to ANVISA. On the psychrotrophic bacteria count there was a variation of 1.46 to 4.10 expressed in log10 values. Of the 28 samples analyzed for the presence of Salmonella spp., in 5 the presence of this microorganism was verified in 25 g. In regard to humidity, all the samples were found to be in accordance with the established legislation (lower than 70% humidity), and for water activity the limits varied between 0.772 and 0.809. The pH values were within normalcy, ranging from 5.7 to 6.2. In spite of the fact that the analyzed samples are in accordance with Brazilian laws, it is necessary to apply good practices, since the contamination by psychrotrophic microorganisms and Salmonella was significant and could harm the public health and reduce the product’s shelf life.

Avaliação microbiológica e físico-química de linguiça toscana no Município de Mossoró, RN

Aiming to evaluate the microbiological and physico-chemical quality of the toscana sausage commercialized in the city of Mossoró, state of Rio Grande do Norte, Brazil, samples from 6 supermarkets were analyzed, verifying the most likely number (MLN) of thermotolerant coliforms, Salmonella spp. , and psychrotrophic bacteria, humidity, pH and water activity. All the samples were within the current standards which establish a maximum limit of 5 x 10³ MLN/g for thermotolerant coliforms according to ANVISA. On the psychrotrophic bacteria count there was a variation of 1.46 to 4.10 expressed in log10 values. Of the 28 samples analyzed for the presence of Salmonella spp. , in 5 the presence of this microorganism was verified in 25 g. In regard to humidity, all the samples were found to be in accordance with the established legislation (lower than 70% humidity), and for water activity the limits varied between 0.772 and 0.809. The pH values were within normalcy, ranging from 5.7 to 6.2. In spite of the fact that the analyzed samples are in accordance with Brazilian laws, it is necessary to apply good practices, since the contamination by psychrotrophic microorganisms and Salmonella was significant and could harm the public health and reduce the product's shelf life.

Com o objetivo de avaliar a qualidade microbiológica e físico-química da linguiça toscana comercializada no Município de Mossoró, RN, foram analisadas 28 amostras de seis supermercados, verificando-se o Número Mais Provável (NMP) de coliformes termotolerantes, Salmonella spp. e bactérias psicrotróficas, umidade, pH e atividade de água. Todas as amostras estavam dentro do padrão vigente que estabelece um limite máximo de 5 x 10³ NMP/g-1 para coliformes termotole-rantes conforme a ANVISA. Na contagem de bactérias psicrotróficas houve uma variação de 2,9 x 10¹ a 1,31 x 10(4) UFC/g-1. Das 28 amostras pesquisadas quanto a presença de Salmonella spp., em cinco verificou-se a presença deste micro-organismo em 25 g. Para umidade, todas as amostras encontravam-se dentro da legislação estabelecida ( 70%) e para atividade de água os limites variaram de 0,772 a 0,809. Os valores de pH das amostras estavam entre 5,7 e 6,2. Apesar das amostras analisadas estarem dentro do estabelecido pela legislação brasileira, faz necessária a aplicação de boas práticas, visto que a contaminação por micro-organismos psicrotróficos e Salmonella foi significativa, podendo diminuir a vida de prateleira do produto e causar danos a saúde pública.