Tecnologia de Alimentos
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11783
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Item The effects of nisin on Staphylococcus aureus count and the physicochemical properties of Traditional Minas Serro cheese(International Dairy Journal, 2011-02) Carvalho, Antônio Fernandes de; Pires, Ana Clarissa dos Santos; Souza, Ariana Aparecida Campos; Pinto, Maximiliano Soares; Silva, Paulo Henrique Fonseca da; Sobral, Denise; Paula, Junio César Jacinto de; Santos, Adbeel de LimaThis study reports the effect of different concentrations of nisin (0, 100 and 500 IU mL−1) against Staphylococcus aureus in Minas Traditional Serro cheese manufactured with raw milk. We also evaluated the influence of nisin on the physicochemical properties, mechanical characteristics and colour of the cheese over 60 days of ripening. Nisin was effective in reducing S. aureus count in Serro cheese; a reduction of 1.2 and 2.0 log cycles in S. aureus count was observed from the 7th day of ripening for cheese containing 100 IU mL−1 and 500 IU mL−1 of nisin, respectively, compared with the control sample. The major changes in physicochemical properties, mechanical characteristics and colour were associated with cheese ripening, except for the index of ripening, which was lower in the presence of nisin. The addition of nisin is a powerful tool to contribute to the safety of traditional cheese produced with raw milk.Item Microbiological safety of Minas Frescal cheese (MFC) and tracking the contamination of Escherichia coli and Staphylococcus aureus in MFC processing(Foodborne Pathogens and Disease, 2013-10-25) Freitas, Rosangela; Brito, Maria Aparecida Vasconcelos Paiva; Nero, Luís Augusto; Carvalho, Antonio Fernandes deMinas Frescal cheese (MFC) is a traditional food produced and consumed in Brazil, characterized by its soft texture, low sodium, and high moisture content. This study characterized the microbiological contamination by coliforms, Escherichia coli and Staphylococcus aureus, in 99 MFC samples obtained in retail sale and produced by three distinct industrial procedures. Dairy processors were selected to investigate the key points of E. coli and S. aureus contamination during cheese processing. MFC samples produced by the addition of lactic culture presented higher counts of coliforms and E. coli, when compared to other samples ( p < 0.05). MFC samples produced by the addition of rennet alone presented higher counts of S. aureus when compared to other samples ( p < 0.05). Fourteen of 19 MFC samples produced by the addition of lactic culture presented E. coli counts higher than 5 · 10 2 colon-forming units/g. The processing steps after pasteurization were identified as the main sources of E. coli and S. aureus contamination of MFC. Based on the results, MFC was characterized as a potential hazard for consumers due to the high frequency of samples contaminated with E. coli and S. aureus counts in non- compliance with Brazilian standards for sanitary quality and safety.Item Enterotoxigenic potential of Staphylococcus aureus isolated from Artisan Minas cheese from the Serra da Canastra - MG, Brazil(Food Science and Technology, 2013-02-13) Dores, Milene Therezinha das; Dias, Ricardo Souza; Arcuri, Edna Froeder; Nobrega, Juliana Escarião da; Ferreira, Célia Lucia de Luces FortesThis 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.Item Room temperature aging to guarantee microbiological safety of Brazilian artisan Canastra cheese(Food Science and Technology, 2012-12-10) Dores, Milene Therezinha das; Nobrega, Juliana Escarião da; Ferreira, Célia Lucia de Luces FortesCanastra 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.Item Detection of exopolysaccharide production and biofilm-related genes in Staphylococcus spp. isolated from a poultry processing plant(Food Science and Technology, 2014-10-01) Ferreira, Andreza Angélica; Tette, Patrícia Amaral Souza; Mendonça, Regina Célia Santos; Soares, Ariana de Souza; Carvalho, Márcia Maria DeStaphylococcus spp. can survive in biofilms for long periods of time, and they can be transferred from one point to another and cause environmental contamination in food processing. The aim of this study was to detect Staphylococcus strains isolated from a poultry processing plant by the presence of adhesion genes and the phenotypic production of exopolysaccharide. In the present study, the production of exopolysaccharide and the presence of adhesion genes in 65 strains of Staphylococcus spp. were evaluated. All strains of Staphylococcus spp. produced exopolysaccharide, as confirmed by formation of black and opaque colonies in Congo Red Agar. The variation of sucrose content was critical for the production of exopolysaccharide in Congo Red Agar since at low sucrose concentrations all strains presented a characteristic result, i.e., there was no exopolysaccharide production. The atl gene was found in all strains, and the icaA and icaD genes were found in 97% of them. The data obtained suggest that Staphylococcus spp. isolated from the poultry processing plant evaluated has a potential for biofilm formation. An efficient control of this microorganism in food processing environment is necessary as they may represent a potential risk to consumers.