ABSTRACT
ABSTRACT Sour cassava starch (Polvilho azedo) is obtained from a spontaneous fermentation conducted by microorganisms from raw materials and fermentation tanks. This product is traditionally used in the baking industry for the manufacture of biscuits and Brazilian cheese breads. However, the end of fermentation is evaluated empirically, and the process occurs without standardization, which results in products of inconsistent quality. Predominant microbiota from a cassava flour manufacturer was isolated in order to select starter cultures for the production of sour cassava starch in a pilot-scale fermentation process. Lactic acid bacteria and yeasts were isolated, enumerated and grouped by Restriction Fragment Length Polymorphism, and PCR fingerprinting, respectively. One isolate of each molecular profile was identified by sequencing of the rRNA gene. LAB were prevalent throughout the entire process. Lactobacillus brevis (21.5%), which produced the highest values of acidity, and Lactobacillus plantarum (13.9%) were among the most frequent species. Pichia scutulata (52.2%) was the prevalent yeast and showed amylolytic activity. The aforementioned species were tested as single and mixed starter cultures in a pilot-scale fermentation process for 28 days. L. plantarum exhibited better performance as a starter culture, which suggests its potential for the production of sour cassava starch.
Subject(s)
Starch/metabolism , Yeasts/metabolism , Manihot/chemistry , Lactobacillus/metabolism , Starch/chemistry , Yeasts/genetics , Brazil , Manihot/metabolism , Fermentation , Microbiota , Food Microbiology , Lactobacillus/isolation & purification , Lactobacillus/geneticsABSTRACT
Do total de 20 culturas de fungos e bactérias isoladas do solo e de produtos de laticínios foram selecionados 8 microrganismos (5 fungos e 3 bactérias) por sua atividade coagulante de leite. Essa atividade estava invariavelmente associada à açäo proteolítica, nos isolados fúngicos e bacterianos. Contudo, as duas atividades enzimáticas parecem ser independentes. Houve variaçäo considerável, na relaçäo entre as duas atividades de uma linhagem para outra e de um meio de cultura para outro, para a mesma linhagem. Uma linhagem de Aspergillus e outra de Bacillus foram selecionadas pela relaçäo entre a atividade coagulante sobre o leite e a atividade proteolítica e pela produçäo da atividade coagulante do leite, respectivamente
Subject(s)
Aspergillus/isolation & purification , Soil Microbiology , Bacillus/isolation & purification , Dairy Products/microbiologyABSTRACT
Em amostras de milho em grão, safra 1984, coletadas em diversas localidades do Estado de Minas Gerais, foi verificada a incidência de aflatoxinas, ocratoxina A e zearalenona. Foi utilizada a técnica de cromatografia em camada delgada. Das 83 amostras analisadas, 15 apresentaram aflatoxinas e apenas uma apresentou zearalenona. Não foi detectada ocratoxina A em nenhuma das amostras (AU).