Caracterização microscópica e microbiológica do biofilme dos utensílios de madeira utilizados na fabricação de queijo minas artesanal das regiões do Serro e Canastra

• Ano de defesa: 2011
• Autor(a) principal: Ferreira, éder Galinari
• Orientador(a): Ferreira, Célia Lúcia de Luces Fortes
• Banca de defesa: Pires, Ana Clarissa dos Santos , Neves, Clóvis Andrade
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Biofilme; Queijo Minas artesanal; Segurança alimentar
• Palavras-chave em Inglês: Biofilm; Artisanal Minas cheese; Food security
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/2897

Due to inexistence of studies on the composition of biofilms formed in the wooden utensils used in the manufacture of artisanal Minas cheese, the aim of this study was to characterize microscopical and microbiologically the biofilm on wooden forms, tables and shelves from Serro and Canastra regions. To evaluate the biofilm samples were removed from the surfaces of three forms, six tables and four shelves in the region of Serro and three tables and three shelves in the region of Canastra. The number of samples corresponds to almost the totality of wooden utensils still in use in both regions, since these utensils have been abolished by the State Law No. 14,185 of January 31, 2002. We used the swab method, limiting the sampling area with sterile template of 100 cm2 for the tables and shelves and 4 cm2 for the forms. At the tables, were collected three samples of 100 cm2, with one at center and two at their extremities. The three points were plated separately to obtain the average. We collected on the shelf a sample of 100 cm2. In each form, four points were collected using the same swab, totaling an area of 16 cm2. Samples of milk, endogenous culture and cheese ripened were also obtained, being five samples of milk, four of endogenous culture and three of cheese in Serro. In Canastra we evaluated three samples of milk, three of endogenous culture and three of cheese. The samples were plated in depth in the media Plate Count Agar (total aerobic mesophiles), Potato Dextrose Agar (yeast), MRS in anaerobic conditions (mesophilic Lactobacillus spp.), M17 in aerobic conditions (Lactococcus spp.) and specific Petrifilm® plates for Staphylococcus aureus, Escherichia coli and coliforms at 32 ºC. Ripened cheeses were evaluated also the presence of Salmonella sp. and Listeria sp. using Reveal kits (Neogen®), that involves a pre-enrichment step. Fragments of wooden utensils were obtained for biofilm evaluation in scanning electron microscopy. Of the cheeses tested, only one sample from Serro had counts of S. aureus and coliforms at 32 ºC above standards legislation. In Canastra, two cheese samples exceeded current levels for E. coli and coliforms at 32 ºC, and only one milk sample remained below the standards for these counts. On the other hand, a sample of endogenous culture from Serro exceeded the limits for E. coli and coliforms at 32 ºC and two exceeded the limits for S. aureus. Samples of endogenous culture from Canastra remained within the standards established in this research. Most of the utensils from Serro had counts below the limits proposed in this study even when high numbers of pathogens were observed in samples of milk and endogenous culture, indicating the importance of the higher acidity of the cheese in this region. The opposite was seen in utensils of Canastra, with only the shelves below the mean established for E. coli. There was no Salmonella sp. and Listeria sp. in all ripened cheeses. High counts of lactic acid bacteria mesophilic Lactobacillus spp. and Lactococcus spp. were found in wooden utensils in both regions. These bacteria are essential for the maturation of the cheese and help to control undesirable microorganisms, ensuring product safety. In addition to cocci and bacilli, yeasts and filamentous fungi were also observed in the electronic photomicrographs, demonstrating the diversity of these biofilms. The results of this study suggest that the technology employed and the lowest levels of contamination of raw materials are essential to the quality of the final product. Thus, it is important to the implementation and maintenance of good manufacturing practices at all stages of the cheese processing, to ensure a safe product and yet, with the traditional characteristics of artisanal Minas cheese kept.