Microbial safety status of Serro artisanal cheese produced in Brazil.

Considering the growing consumption of artisanal foods worldwide, we aimed to evaluate the microbial safety of Serro artisanal cheese (SAC), produced in Minas Gerais State, Brazil. This cheese is produced with raw milk using 1 of 2 natural starter cultures: "pingo" and "rala." A total of 53 SAC samples (pingo = 8; rala = 45) were obtained from different farmers and subjected to conventional and molecular assays to detect and enumerate Listeria monocytogenes, Salmonella spp., coagulase-positive staphylococci (CPS), diarrheagenic Escherichia coli, Mycobacterium tuberculosis, and Brucella abortus. The SAC samples were also subjected to an ELISA to detect classical staphylococcal enterotoxins (CSE: SEA, SEB, SEC, SED, SEE) and to PCR assays to detect staphylococcal enterotoxin-related genes (sea, seb, sec, sed, see). Coagulase-positive staphylococci isolates were obtained and tested by the same assays to detect their potential in CSE production and presence of CSE-related genes. None of the SAC samples showed any of the screened food-borne pathogens and zoonotic agents, and none showed the presence of CSE by phenotypic and genotypic approaches. Despite the absence of microbial hazards, mean counts of CPS in SAC samples were 5.2 log cfu/g (pingo starter) and 4.6 log cfu/g (rala starter), indicating poor hygiene practices during production. None of the tested CPS isolates (n = 116) produced CSE or presented CSE-related genes. Despite the relative microbial safety, hygienic conditions during SAC production must be improved to meet official guidelines established in Brazil.

Determining the minimum ripening time of artisanal Minas cheese, a traditional Brazilian cheese.

Physical, physicochemical, and microbiological changes were monitored in 256 samples of artisanal Minas cheese from eight producers from Serro region (Minas Gerais, Brazil) for 64 days of ripening to determine the minimum ripening time for the cheese to reach the safe microbiological limits established by Brazilian legislation. The cheeses were produced between dry season (April-September) and rainy season (October-March); 128 cheeses were ripened at room temperature (25 ± 4 °C), and 128 were ripened under refrigeration (8 ± 1 °C), as a control. No Listeria monocytogenes was found, but one cheese under refrigeration had Salmonella at first 15 days of ripening. However, after 22 days, the pathogen was not detected. Seventeen days was the minimum ripening time at room temperature to reduce at safe limits of total coliforms > 1000 cfu.g (-1) ), Escherichia coli and Staphylococcus aureus (> 100 cfu.g (-1) ) in both periods of manufacture. Otherwise under refrigeration, as expected, the minimum ripening time was longer, 33 days in the dry season and 63 days in the rainy season. To sum up, we suggest that the ripening of artisanal Minas cheese be done at room temperature, since this condition shortens the time needed to reach the microbiological quality that falls within the safety parameters required by Brazilian law, and at the same time maintain the appearance and flavor characteristics of this traditional cheese.

Microbiological aspects of the biofilm on wooden utensils used to make a Brazilian artisanal cheese.

The artisanal Minas cheese is produced from raw cow's milk and wooden utensils were employed in its manufacture, which were replaced by other materials at the request of local laws. This substitution caused changes in the traditional characteristics of cheese. Due to the absence of scientific studies indicating the microbial composition of biofilms formed on wooden forms, tables and shelves used in these cheese production, the present work evaluated the counts of Staphylococcus aureus, Escherichia coli, coliforms at 32 °C, yeasts, presumptive mesophilic Lactobacillus spp. and Lactococcus spp. in these biofilms, milk, whey endogenous culture and ripened cheese in two traditional regions: Serro and Serra da Canastra. Also, we checked for the presence of Salmonella sp. and Listeria monocytogenes in the ripened cheeses. The ultra structure of the biofilms was also assessed. Counts above legislation (> 2 log cfu/mL) for the pathogens evaluated were found in milk samples from both regions. Only one shelf and one form from Serro were above limits proposed (5 cfu/cm(2) for S. aureus and E. coli and 25 cfu/cm(2) for coliforms) in this study for contaminants evaluated. In Canastra, few utensils presented safe counting of pathogens. There was no Salmonella sp. and Listeria monocytogenes in the cheeses after ripening. Thus, the quality of the cheese is related to improving the microbiological quality of milk, implementation and maintenance of good manufacturing practices, correct cleaning of wooden utensils, and not its replacement.

Determining the minimum ripening time of artisanal Minas cheese, a traditional Brazilian cheese

Physical, physicochemical, and microbiological changes were monitored in 256 samples of artisanal Minas cheese from eight producers from Serro region (Minas Gerais, Brazil) for 64 days of ripening to determine the minimum ripening time for the cheese to reach the safe microbiological limits established by Brazilian legislation. The cheeses were produced between dry season (April–September) and rainy season (October–March); 128 cheeses were ripened at room temperature (25 ± 4 °C), and 128 were ripened under refrigeration (8 ± 1 °C), as a control. No Listeria monocytogenes was found, but one cheese under refrigeration had Salmonella at first 15 days of ripening. However, after 22 days, the pathogen was not detected. Seventeen days was the minimum ripening time at room temperature to reduce at safe limits of total coliforms > 1000 cfu.g−1), Escherichia coli and Staphylococcus aureus (> 100 cfu.g−1) in both periods of manufacture. Otherwise under refrigeration, as expected, the minimum ripening time was longer, 33 days in the dry season and 63 days in the rainy season. To sum up, we suggest that the ripening of artisanal Minas cheese be done at room temperature, since this condition shortens the time needed to reach the microbiological quality that falls within the safety parameters required by Brazilian law, and at the same time maintain the appearance and flavor characteristics of this traditional cheese.

Microbiological aspects of the biofilm on wooden utensils used to make a Brazilian artisanal cheese

The artisanal Minas cheese is produced from raw cow's milk and wooden utensils were employed in its manufacture, which were replaced by other materials at the request of local laws. This substitution caused changes in the traditional characteristics of cheese. Due to the absence of scientific studies indicating the microbial composition of biofilms formed on wooden forms, tables and shelves used in these cheese production, the present work evaluated the counts of Staphylococcus aureus, Escherichia coli, coliforms at 32 °C, yeasts, presumptive mesophilic Lactobacillus spp. and Lactococcus spp. in these biofilms, milk, whey endogenous culture and ripened cheese in two traditional regions: Serro and Serra da Canastra. Also, we checked for the presence of Salmonella sp. and Listeria monocytogenes in the ripened cheeses. The ultra structure of the biofilms was also assessed. Counts above legislation (> 2 log cfu/mL) for the pathogens evaluated were found in milk samples from both regions. Only one shelf and one form from Serro were above limits proposed (5 cfu/cm² for S. aureus and E. coli and 25 cfu/cm² for coliforms) in this study for contaminants evaluated. In Canastra, few utensils presented safe counting of pathogens. There was no Salmonella sp. and Listeria monocytogenes in the cheeses after ripening. Thus, the quality of the cheese is related to improving the microbiological quality of milk, implementation and maintenance of good manufacturing practices, correct cleaning of wooden utensils, and not its replacement.