The aim of this work was to study the yeast populations and the main hygienic-sanitary microbial indicators in water buffalo mozzarella produced and commercialized in Minas Gerais, Brazil. Forty-two water buffalo mozzarella samples were purchased from retail outlets in Belo Horizonte. In addition, five samples of consecutive starter cultures, curd before acidification, acidified curd and mozzarella were collected at an industry in the city of Oliveira. Only three of the five water samples analyzed were suitable for consumption according to Brazilian sanitary standards. Four milk samples were highly contaminated with fecal coliforms, and did not meet the minimal hygienic-sanitary standards according to Brazilian regulations. Only one sample of buffalo muzzarela purchased from retail outlets exceeded the limit for coagulase-positive Staphylococcus. Eleven samples showed counts of thermotolerant coliforms higher than5x 10³ CFU.g-1, but still lower than the maximum permitted by the Brazilian laws. Salmonella spp. and Listeria monocytogenes were not isolated. Debaryomyces hansenii, Candida lusitaniae and C. parapsilosis were the prevalent yeast species isolated from cheese. Among samples from the production stages, the acidified curd presented the highest numbers of yeasts, with C. catenulata being the most frequent species isolated. Some opportunistic yeast species such as C. guilliermondii, C. tropicalis, C. parapsilosis, C. lusitaniae, C. catenulata, C. rugosa and C. krusei occurred in the mozzarella cheese samples analyzed. The mozzarella cheese presented a low microbial load as compared to other cheese already studied, and the yeast biota included species typical of cheese and also opportunistic pathogens.

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.

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.