Browsing by Author "Borges, Ana Maria Rêgo"
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- Evolução da população microbiana ao longo do processo de fermentação natural de azeitonas de mesa da cultivar Negrinha de FreixoPublication . Borges, Ana Maria Rêgo; Pereira, Ermelinda; Baptista, PaulaA “Azeitona de Conserva Negrinha de Freixo” é um produto de denominação de origem protegida (DOP), da região do Nordeste Transmontano, consumida após tratamento ou em salmoura. Este trabalho pretendeu avaliar a evolução da população microbiana (mesófilos, bactérias lácticas, bolores e leveduras) ao longo do processo de fermentação natural, em salmoura, de azeitonas de mesa da cultivar Negrinha de Freixo. Pretendeu-se ainda identificar morfologicamente e molecularmente, através da amplificação termocíclica da região internal transcribed spacer (ITS) do rDNA nuclear, as espécies de leveduras presentes durante a fermentação e correlacionar a sua presença com os parâmetros químicos avaliados na salmoura (pH e acidez titulável). Os resultados indicam que a fase inicial do processo de fermentação natural é conduzida maioritariamente por leveduras e numa fase posterior também por bactérias lácticas. A identificação de leveduras durante a fermentação permitiu registar um total de 1130 isolados na salmoura e de 1492 na polpa, pertencentes ao género Candida, Pichia, Saccharomyces, Debaryomyces, Galactomyces e Rhodotorula. As espécies mais abundantes na salmoura e polpa de azeitona foram S. cerevisiae, C. tropicalis, P. membranifaciens e C. boidinii. Ao longo do processo de fermentação registaram-se variações na população de leveduras predominando nos primeiros 4 dias C. boidinii na salmoura e P. membranifaciens na polpa, e a partir dos 17 dias S. cerevisiae e C. tropicalis em ambas as matrizes. A diversidade de espécies de leveduras foi superior na salmoura face à polpa, durante todo o processo fermentativo, apresentando valores máximos a partir dos 44-54 dias. A dinâmica populacional das leveduras mostrou estar significativamente correlacionada com o valor de pH e acidez, em que decorre o processo fermentativo. Espera-se que os resultados possam contribuir para a melhoria das condições de fermentação da “Azeitona de Conserva Negrinha de Freixo”, permitindo o aumento da sua qualidade e, simultaneamente, da sua segurança.
- Microbial population associated to the fermentation process of “Negrinha de Freixo” table olives produced in PortugalPublication . Borges, Ana Maria Rêgo; Baptista, Paula; Pereira, J.A.; Pereira, Ermelinda“Negrinha de Freixo” is a typical table olive cultivar of the Northeastern region of Portugal, processed according to the natural fermentation methodology. Due to its distinctive characteristics, the “Negrinha de Freixo” table olives have been identified as Protected Designation of Origin (PDO). Despite its importance, no information about the microflora composition occurring in the fermentation process is available. The aim of the present study was to evaluate changes in some chemical characteristics and microbiological composition in brine during “Negrinha de Freixo” spontaneous fermentation. The microbial groups assessed by culture-dependent analysis were yeasts and lactic acid bacteria; and the chemical analysis included the measure of the pH and titratable acidity. The results indicate that yeasts were the main group of microorganisms involved during all fermentation process, but lactic acid bacteria (LAB) were also important in the second phase. Yeast and LAB populations ranged in 5.0-6.3 log cfu/ml and 2.3-5.8 log ufc/ml, respectively, during de fermentation. The final pH and the titratable acidity were 3.36 and 0.90 g of lactic acid/100ml, respectively. The yeasts population dynamics was showed to be significantly correlated with the pH and acidity values that occur during the fermentation process. The results obtained from this study could contribute to the improvement of fermentation processing, allowing the increase of their quality and simultaneously of their safety.
- Microbial population associated to the fermentation process of “Negrinha de Freixo” table olives produced in PortugalPublication . Borges, Ana Maria Rêgo; Baptista, Paula; Pereira, J.A.; Pereira, Ermelinda“Negrinha de Freixo” is a typical table olive cultivar of the Northeastern region of Portugal, processed according to the natural fermentation methodology. Due to its distinctive characteristics, the “Negrinha de Freixo” table olives have been identified as Protected Designation of Origin (PDO). Despite its importance, no information about the microflora composition occurring in the fermentation process is available. The aim of the present study was to evaluate changes in some chemical characteristics and microbiological composition in brine during “Negrinha de Freixo” spontaneous fermentation. The microbial groups assessed by culture-dependent analysis were yeasts and lactic acid bacteria; and the chemical analysis included the measure of the pH and titratable acidity. The results indicate that yeasts were the main group of microorganisms involved during all fermentation process, but lactic acid bacteria (LAB) were also important in the second phase. Yeast and LAB populations ranged in 5.0-6.3 log cfu/ml and 2.3-5.8 log ufc/ml, respectively, during de fermentation. The final pH and the titratable acidity were 3.36 and 0.90 g of lactic acid/100ml, respectively. The yeasts population dynamics was showed to be significantly correlated with the pH and acidity values that occur during the fermentation process. The results obtained from this study could contribute to the improvement of fermentation processing, allowing the increase of their quality and simultaneously of their safety.
- Yeast dynamics during the natural fermentation process of table olives (Negrinha de Freixo cv.)Publication . Pereira, Ermelinda; Ramalhosa, Elsa; Borges, Ana Maria Rêgo; Pereira, J.A.; Baptista, PaulaYeast population and dynamics associated to spontaneous fermentation of green table olives Negrinha de Freixo cv. were evaluated. Olives and brine samples were taken at different fermentation times, and yeast were enumerated by standard plate count and identified by sequencing of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (rDNA). Saccharomyces cerevisiae was the most frequent, followed by Candida tropicalis, Pichia membranifaciens and Candida boidini, representing together 94.8% of the total isolates. Galactomyces reessii was also identified for the first time in table olives. The highest species diversity was found between 44 and 54 days of fermentation, both in brine and olive pulp. Furthermore, high similarity was observed between brine and olive pulp microbiotas. In conclusion, these results give valuable information to table olive industrials in order to achieve more knowledge on the fermentation process of this important Protected Designation of Origin product.