1
tesis de grado
Publicado 2022
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Analiza los niveles de acrilamida en hojuela de papas fritas comercializadas en el año 2018 y comparar su situación frente a los valores de referencia establecidos internacionalmente. Fueron evaluadas 16 marcas de hojuelas de papas fritas (M1 a M16) provenientes de 9 productores. Fueron analizadas por cromatografía HPLC con columna HILIC, usando el método QUECHERS para su extracción y limpieza con factor de recuperación de 77,9%. Los niveles de acrilamida fueron expresados en μg/kg y comparados con los valores establecidos de la Unión Europea. Resultados: 12 de las 16 marcas, presentaron niveles promedio de acrilamida entre 868 y 2591 μg/kg; 2 de los 9 productores (fabricante de marcas M3, M6, M11 y M12) presentaron los más bajos niveles de acrilamida, con una media entre 386 y 540 μg/kg. Las muestras M1 y M8, de mayor distribución y probablemente mayor consumo, presentaron n...
2
artículo
Publicado 2023
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“Microorganisms from extreme environments, such as the Antarctic ecosystems, have a great potential to produce enzymes with novel characteristics. Within this context, L-asparaginase (ASNase) obtained from yeast species has been poorly studied. In this study, yeasts isolated from samples collected at Admiralty Bay (King George Island, Antarctica) were tested to produce ASNase. From an initial screening of 40 strains, belonging to 13 different species, Leucosporidium scottii L115 produced an ASNase activity (LsASNase activity: 6.24 U g-1 of dry cell weight) with the lowest glutaminase activity. The LsASNase was purified 227-fold, with a specific activity of 137.01 U mg-1 at 37 ◦C, without glutaminase activity. Moreover, the maximum enzyme activity was observed at pH 7.5 and at a temperature of 55 ◦C. The enzyme is a multimer of 462 kDa, presenting a single band of 53 kDa molecular m...
3
artículo
Publicado 2023
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“Microorganisms from extreme environments, such as the Antarctic ecosystems, have a great potential to produce enzymes with novel characteristics. Within this context, L-asparaginase (ASNase) obtained from yeast species has been poorly studied. In this study, yeasts isolated from samples collected at Admiralty Bay (King George Island, Antarctica) were tested to produce ASNase. From an initial screening of 40 strains, belonging to 13 different species, Leucosporidium scottii L115 produced an ASNase activity (LsASNase activity: 6.24 U g-1 of dry cell weight) with the lowest glutaminase activity. The LsASNase was purified 227-fold, with a specific activity of 137.01 U mg-1 at 37 ◦C, without glutaminase activity. Moreover, the maximum enzyme activity was observed at pH 7.5 and at a temperature of 55 ◦C. The enzyme is a multimer of 462 kDa, presenting a single band of 53 kDa molecular m...
4
artículo
L-asparaginase (EC 3.5.1.1) hydrolyzes L-asparagine in L-aspartic acid and ammonia. Its efficiency is subject to its kinetics and specificity on the substrate, characteristics that vary from one source to another. Thus, microorganisms from saline environments constitute a phylogenetic and metabolically heterogeneous group for the search of new enzymes. Therefore, the objective of this study was the phenotypic and genotypic characterization of bacteria with L-asparaginase activity isolated from Maras, Pilluana and Chilca salterns. The 24 evaluated bacteria were classified as 38% Gram-negative bacilli and 54% positive; and 8% Gram-positive cocci. The majority grew in 5% salt water, pH 7.0 and 37 °C, all assimilated glucose. Of the 24 bacteria that produced L-asparaginase in solid medium, enzymatic activity was determined in submerged cultures by the Nessler method in 14 of them. The CH11,...