This study aimed to evaluate the presence of enterotoxigenic S. aureus in the endogenous starter and in Artisan Minas cheeses from the Serra da Canastra. Sixteen samples of endogenous starters and cheese were collected during the rainy and dry seasons. The isolation and enumeration of S. aureus were performed using the PetrifilmTM-Rapid S. aureus Plate Count method. The presence of enterotoxin in the cheese samples was analyzed by the Optimal Sensitivity Plate (OSP) method and the ELFA-VIDAS®-Staph enterotoxin-II assay. S. aureus strains were tested for their ability to produce enterotoxins using the Optimal Sensitivity Plate (OSP) method and the polymerase chain reaction (PCR) assay for the classical enterotoxin genes. The Optimal Sensitivity Plate (OSP) method data showed that staphylococcal enterotoxin A (SEA) was detected in 75% of the cheese samples, but no toxin was detected with the ELFA-VIDAS method. It was found that 12.5% of the isolated strains produced staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin C (SEC). When using the the polymerase chain reaction (PCR) assay, only one isolate was found to harbor an enterotoxin gene, contrary our expectations. However, discrepancies between the immunological and molecular assays are not uncommon. Despite the fact that most isolates did not produce classical enterotoxins, high S. aureus counts in the cheese samples causes concern since there is a risk of the presence of non-classical enterotoxins.

O queijo Canastra é um dos mais antigos e tradicionais queijos produzidos com leite cru no Brasil, no entanto, sua produção pode gerar consequências graves para a saúde. De acordo com lei vigente no País, o queijo feito com leite cru deve ser submetido a um período mínimo de maturação de 60 dias. Tradicionalmente o queijo canastra é consumido após diferentes períodos de maturação, sendo priorizados pelo consumidor os queijos com menos de 8 dias de fabricação. O objetivo deste estudo foi avaliar a modulação de variáveis físico-químicas e microbiológicas, com ênfase na microbiota patogênica regulamentada por lei, no queijo maturado em temperatura ambiente e sob refrigeração. Amostras de queijos foram coletadas em oito propriedades na região, em dois períodos do ano (chuvoso e seco), e analisadas com 8, 15, 22, 29, 36 e 64 dias de fabricação. A maturação em temperatura ambiente foi decisiva para redução da microbiota patogênica para níveis permitidos em 22 dias, nos dois períodos analisados, ao passo que, sob refrigeração, os níveis de Staphylococcus aureus (espécie limitante) permitidos somente seriam atingidos após 64 dias. Dessa forma, mantendo-se a tradição, o queijo canastra maturado por 22 dias em temperatura ambiente apresenta os requisitos legais de segurança.

Canastra cheese is one of the oldest and most traditional cheeses made from raw milk in Brazil. However, this type of practice may have severe consequences for human health. According to the current legislation, any cheese made from raw milk must be aged for at least 60 days. Traditionally, Canastra cheese is consumed after different ripening periods, but consumers usually prefer those that are aged less than eight days. This study aimed to evaluate the effects of physicochemical and microbiological parameters, with emphasis on the pathogenic microbiota regulated by law, on cheese aged at room temperature and under refrigeration. Cheese samples were collected from eight different cheese producers located in the Serra da Canastra region twice a year (rainy and dry seasons) and analyzed with 8, 15, 22, 29, 36, and 64 days of ripening. Room temperature aging effectively reduced pathogens, reaching the total count established by law in 22 days, regardless of the season. However, ripening under refrigeration, it was ineffective in reducing the Staphylococcus aureus counts to the legislation limits, even after 64 days. Therefore, Canastra cheese should be ripened for at least 22 days at room temperature in order to fulfill the safety regulatory limits.