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Braz. j. microbiol ; 49(4): 808-815, Oct.-Dec. 2018. tab, graf
Article in English | LILACS | ID: biblio-974288


ABSTRACT Chicha, a type of beer made mainly with maize or cassava, is a traditional fermented beverage of the Andean region. There have only been a few studies on yeasts associated with chicha fermentation, and the species diversity occurring during the production of this beverage is not known. The objective of this study was to determine the biodiversity of yeasts in chicha, and to characterize the Saccharomyces cerevisiae populations associated with the production of chicha de jora, seven-grain chicha, chicha de yuca, and chicha de morocho in Ecuador. The molecular diversity of S. cerevisiae populations was determined by restriction polymorphism mitochondrial profiles. The beverages were characterized based on their physicochemical parameters. Twenty-six species were identified, and the most prevalent species were S. cerevisiae and Torulaspora delbrueckii. Other yeast species were isolated at low frequencies. Among 121 isolates of S. cerevisiae, 68 different mtDNA molecular profiles were identified. These results showed that chichas are fermented by a high number of different strains of S. cerevisiae. Some other species provided a minor contribution to the fermentation process. The chicha presented generally similar physicochemical parameters to those observed for other traditional fermented beverages, and can be considered as an acid fermented beverage.

Saccharomyces cerevisiae/isolation & purification , Beer/microbiology , Yeasts/isolation & purification , Yeasts/metabolism , Saccharomyces cerevisiae/classification , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Beer/analysis , Yeasts/classification , Yeasts/genetics , Manihot/metabolism , Manihot/microbiology , Zea mays/metabolism , Zea mays/microbiology , Biodiversity , Ecuador , Fermentation
Braz. j. microbiol ; 48(4): 740-746, Oct.-Dec. 2017. tab, graf
Article in English | LILACS | ID: biblio-889173


ABSTRACT The spoilage of beer by bacteria is of great concern to the brewer as this can lead to turbidity and abnormal flavors. The polymerase chain reaction (PCR) method for detection of beer-spoilage bacteria is highly specific and provides results much faster than traditional microbiology techniques. However, one of the drawbacks is the inability to differentiate between live and dead cells. In this paper, the combination of propidium monoazide (PMA) pretreatment and conventional PCR had been described. The established PMA-PCR identified beer spoilage Lactobacillus brevis based not on their identity, but on the presence of horA gene which we show to be highly correlated with the ability of beer spoilage LAB to grow in beer. The results suggested that the use of 30 µg/mL or less of PMA did not inhibit the PCR amplification of DNA derived from viable L. brevis cells. The minimum amount of PMA to completely inhibit the PCR amplification of DNA derived from dead L. brevis cells was 2.0 µg/mL. The detection limit of PMA-PCR assay described here was found to be 10 colony forming units (CFU)/reaction for the horA gene. Moreover, the horA-specific PMA-PCR assays were subjected to 18 reference isolates, representing 100% specificity with no false positive amplification observed. Overall the use of horA-specific PMA-PCR allows for a substantial reduction in the time required for detection of potential beer spoilage L. brevis and efficiently differentiates between viable and nonviable cells.

Staining and Labeling/methods , Beer/microbiology , Lactobacillus brevis/isolation & purification , Lactobacillus brevis/growth & development , Real-Time Polymerase Chain Reaction/methods , Propidium/analogs & derivatives , Propidium/chemistry , Azides/chemistry , Lactobacillus brevis/genetics , Lactobacillus brevis/chemistry , Real-Time Polymerase Chain Reaction/instrumentation , Food Microbiology
Hig. aliment ; 30(256/257): 142-147, maio/junho 2016. ilus
Article in Portuguese | LILACS | ID: biblio-1703


A cerveja é uma bebida alcoólica comercializada frequentemente em latas de alumínio devido à praticidade no consumo. Este tipo de embalagem entra em contato direto com a boca do consumidor e necessita de um cuidado redobrado com relação aos aspectos de higienização para não ser um veículo de micro-organismos patogênicos. O trabalho objetivou avaliar a presença de micro-organismos aeróbios mesófilos e enterobactérias nas superfícies das latas de cerveja comercializadas no município de Itabuna, Bahia. Foram coletadas 48 latas de cerveja (24 com vendedores ambulantes e 24 em supermercados) no mês de setembro de 2012 e realizou-se a Técnica do Esfregaço de Superfície com plaqueamento do inóculo em profundidade nos meios de cultura PCA e VRBD. A presença dos micro-organismos aeróbios mesófilos foi determinada com contagens acima de 300 UFC/cm², em 70,8% e 12,5% das amostras coletadas com ambulantes e em supermercados, respectivamente. Já as enterobactérias tiveram presença acima de 300 UFC/cm² em 37,5% das amostras dos ambulantes e contagens abaixo de 50 UFC/cm² em 100% das amostras coletadas em supermercados. As altas contagens de micro-organismos aeróbios mesófilos e enterobactérias na superfície das latas coletadas com ambulantes indicaram a necessidade de boas práticas higiênicas na comercialização da bebida.

Beer is an alcoholic beverage often marketed in aluminum cans because of the convenience in use. This type of packaging is in direct contact with the consumer's mouth and needs a special care regarding the hygiene aspects not to be a vehicle of pathogenic microorganisms. The study aimed to evaluate the presence of mesophilic aerobic microorganisms and enterobacteria on the surfaces of cans of beer sold in the city of Itabuna, Bahia. They collected 48 cans of beer (24 with street vendors and 24 supermarkets) in September 2012 and held the surface smear technique with the plating of inoculum in depth in the PCA and VRBD culture media. The presence of mesophilic aerobic microorganisms was determined above 300 CFU / cm² counts in 70.8% and 12.5% of the samples collected from street and supermarkets, respectively. Enterobacteria already had presence above 300 CFU / cm² in 37.5% of samples of street and scores below 50 CFU / cm² at 100% of the samples collected in supermarkets. The high counts of mesophilic aerobic microorganisms and enterobacteria on the surface of cans collected with street indicated the need for good hygienic practices in the marketing of the drink.

Beer/microbiology , Environmental Pollution/analysis , Food Packaging/standards , Alcoholic Beverages , Microbiology , Brazil , Enterobacteriaceae/isolation & purification , Street Food , Products Commerce
Rev. argent. microbiol ; 39(3): 170-176, jul.-sep. 2007. graf, tab
Article in English | LILACS | ID: lil-634554


Different natural antimicrobials affected viability of bacterial contaminants isolated at critical steps during a beer production process. In the presence of 1 mg/ml chitosan and 0.3 mg/ml hops, the viability of Escherichia coli in an all malt barley extract wort could be reduced to 0.7 and 0.1% respectively after 2 hour- incubation at 4 °C. The addition of 0.0002 mg/ml nisin, 0.1 mg/ml chitosan or 0.3 mg/ml hops, selectively inhibited growth of Pediococcus sp. in more than 10,000 times with respect to brewing yeast in a mixed culture. In the presence of 0.1mg ml chitosan in beer, no viable cells of the thermoresistant strain Bacillus megaterium were detected. Nisin, chitosan and hops increased microbiological stability during storage of a local commercial beer inoculated with Lactobacillus plantarum or Pediococcus sp. isolated from wort. Pulsed Electric Field (PEF) (8 kV/cm, 3 pulses) application enhanced antibacterial activity of nisin and hops but not that of chitosan. The results herein obtained suggest that the use of these antimicrobial compounds in isolation or in combination with PEF would be effective to control bacterial contamination during beer production and storage.

Diferentes antimicrobianos naturales disminuyeron la viabilidad de bacterias contaminantes aisladas en etapas críticas del proceso de producción de cerveza. En un extracto de malta, el agregado de 1 mg/ml de quitosano y de 0,3 mg ml de lúpulo permitió reducir la viabilidad de Escherichia coli a 0,7 y 0,1%, respectivamente, al cabo de 2 horas de incubación a 4 °C. El agregado de 0,0002 mg/ml de nisina, 0,1 mg/ml de quitosano o de 0,3 mg/ml de lúpulo inhibió selectivamente (10.000 veces más) el crecimiento de Pediococcus sp. respecto de la levadura de cerveza en un cultivo mixto. El agregado de 0,1 mg/ml de quitosano permitió disminuir la viabilidad de una cepa bacteriana termorresistente, Bacillus megaterium, hasta niveles no detectables. Por otra parte, el agregado de nisina, quitosano y lúpulo aumentó la estabilidad microbiológica durante el almacenamiento de cervezas inoculadas con Lactobacillus plantarum y Pediococcus sp. aislados de mosto de cerveza. La aplicación de campos eléctricos pulsantes (CEP) (3 pulsos de 8kV/cm) aumentó el efecto antimicrobiano de la nisina y del lúpulo, pero no el del quitosano. Los resultados obtenidos indicarían que el uso de antimicrobianos naturales en forma individual o en combinación con CEP puede constituir un procedimiento efectivo para el control de la contaminación bacteriana durante el proceso de elaboración y almacenamiento de la cerveza.

Bacillus megaterium/isolation & purification , Beer/microbiology , Chitosan/pharmacology , Electromagnetic Fields , Escherichia coli/isolation & purification , Humulus , Industrial Microbiology/methods , Lactobacillus plantarum/isolation & purification , Nisin/pharmacology , Pediococcus/isolation & purification , Plant Extracts/pharmacology , Bacillus megaterium/drug effects , Bacillus megaterium/growth & development , Bacillus megaterium/radiation effects , Escherichia coli/drug effects , Escherichia coli/growth & development , Escherichia coli/radiation effects , Fermentation , Food Preservation , Lactobacillus plantarum/drug effects , Lactobacillus plantarum/growth & development , Lactobacillus plantarum/radiation effects , Microbial Sensitivity Tests , Pediococcus/drug effects , Pediococcus/growth & development , Pediococcus/radiation effects , Temperature
RBCF, Rev. bras. ciênc. farm. (Impr.) ; 36(1): 139-45, jan.-jun. 2000. ilus, tab, graf
Article in Portuguese | LILACS | ID: lil-276143


Grande número de vantagens obtém-se quando se utiliza o processo de produção de cerveja empregando mostos mais concentrados, conhecido como processo ®High-Gravity¼. Entretanto, problemas relacionados a fermentações incompletas ou lentas são freqüentemente encontrados, ocasionando perda de produtividade e possibilidade de contaminação. A influência dos fatores pH, porcentagem de xarope de milho e concentração inicial de açúcares sobre o grau de fermentação do mosto foram estudados mostrando que a atenuação do mosto é influenciada principalmente pelo pH inicial de fermentação e pela porcentagem de xarope de milho na constituição do mosto, influência essa resultante do favorecimento do transporte de maltose para o interior da célula quando da utilização de valores de pH 4,5 e pela maior quantidade de açúcares fermentescíveis existentes no mosto com adição de xarope

Beer/microbiology , Biotechnology , Saccharomyces cerevisiae/isolation & purification , Fermentation , Hydrogen-Ion Concentration