The influence of ripening period length and season on the microbiological parameters of a traditional Brazilian cheese

The ripening process of Serro Minas cheese, one of the most popular cheeses produced with raw milk in Brazil, was studied over the course of 60 days of ripening during dry and rainy seasons. Brazilian legislation prohibits the production of cheese from raw milk unless it was submitted to a maturation period greater than 60 days. However Minas Serro cheese is sold within a few days of ripening. A total of 100 samples of Serro cheese were obtained from five farms; 50 samples were collected during the dry season (winter in Brazil) and 50 samples were collected during the rainy season (summer in Brazil). From each farm, ten cheeses were collected during each season after two days of ripening. Our results showed high levels of total and fecal coliforms at the beginning of the ripening period (approximately 4 Log MPN/g with 3 days of ripening) that decreased with 60 days of ripening reaching almost 1.5 Log MPN/g. Contamination by coagulase-positive staphylococci was reduced by the end of the ripening period. Salmonella spp. was not detected. The staphylococcal enterotoxins B and C were detected in 1% and 4% of the cheeses, respectively, after 30 days of ripening. These results suggest that the ripening process was not effective in eliminating staphylococcal enterotoxins from the cheese. However, none of the investigated strains of Staphylococcus spp. isolated from Serro cheese produced enterotoxins A, B, C or D. The high pathogen and coliform levels at the beginning of the ripening process for the cheese produced during both seasons indicate the need for improvement of the sanitation of the manufacturing conditions.

Enteroxigenic Staphylococcus spp. and other microbial contaminants during production of Canastra cheese, Brazil

Canastra cheese is produced from raw cow's milk, and it is made at the farmhouse level using artisanal procedures and natural starters. The aim of this work was to determine the main hygienic-sanitary indicators and enterotoxigenic staphylococcal strains present during the manufacturing of traditional cheese of Serra da Canastra region, Minas Gerais state, Brazil. Samples from 10 farms were studied, and they included: water employed in the process, raw milk, natural starters, cheese curd before salting and cheese after five days of ripening. All water samples exhibited faecal coliform contamination above the maximum acceptable value recommended by Brazilian standards. Pseudomonas aeruginosa and sulfite-reducing clostridia were also isolated from the water samples. In five samples of raw milk faecal coliform were above the limits allowed by the Brazilian legislation. The counts of Staphylococcus spp. in milk were between <2.0 to 4.9 log.cfu.ml-1. The counts of microbiological indicators were higher in natural starters and curd. High levels of faecal and total coliform, as well as molds, were found in the cheese samples. In all cheeses analyzed Staphylococcus spp. were found in levels above 5.0 log.cfu.g-1. The enterotoxins (SE) most frequently produced by Staphylococcus spp. strains were SEB and SEC. A high number of coagulase negative Staphylococcus strains were also enterotoxin producers. None of the samples contained Salmonella spp. or Listeria spp. These results point out a need for improvements in the production process of the artisanal cheese produced at Serra da Canastra in Brazil.

O queijo Canastra é produzido a partir de leite cru, e é fabricado em fazendas utilizando procedimentos artesanais e culturas naturais de soro como iniciadoras. O objetivo deste trabalho foi determinar os principais indicadores higiênico-sanitário e as linhagens enterotoxigenicas de Staphylococcus presentes durante a fabricação do queijo tradicional da região da Serra da Canastra, Minas Gerais, Brasil. Amostras provenientes de 10 fazendas foram estudadas, e estas incluíram: a água utilizada no processo, o leite cru, o soro iniciador, a coalhada antes da salga, e o queijo após cinco dias de cura. Todas as amostras de água apresentaram contaminação por coliformes fecais acima do valor máximo recomendado pelos padrões brasileiros. Pseudomonas aeruginosa e clostrídios sufito-redutores também foram isolados das amostras de água. Em cinco amostras de leite cru os coliformes fecais apresentaram-se acima dos limites permitidos pela legislação brasileira. As contagens de Staphylococcus spp. no leite variaram de <2.0 a 4.9 log.ufc.ml-1. As contagens dos indicadores microbiológicos foram maiores no soro iniciador do que na massa coagulada. Níveis altos de contaminação por coliformes totais e fecais, como também bolores, foram observados nas amostras de queijo. Em todos os queijos estudados Staphylococcus spp. foram encontrados em níveis acima de 5.0 log.ufc.g-1. As enterotoxinas mais freqüentes produzidas pelas linhagens de Staphylococcus spp. foram B e C. Um número elevado de linhagens de Staphylococcus coagulase-negativa foram também produtores de enterotoxinas. Em nenhuma das amostras foi isolada Salmonella spp. ou Listeria spp. Estes resultados mostram a necessidade de melhorias no processo de produção do queijo artesanal produzido na Serra da Canastra, Brasil.