In vitro cariogenicity of trans-galactosyl-oligosaccharides.
... Las curvas de acumulación de gas se ajustaron según el modelo propuesto por France et al. (2000), el cual supone que el índice de producción de gas depende del sustrato disponible para fermentación, en un tiempo de colonización alcanzado por los microorganismos según la supuesta tasa fraccional de degradación, representado en la siguiente ecuación: Al finalizar la fermentación, el residuo se recuperó y se congeló a temperatura de - 80oC para el análisis de los ácidos grasos volátiles. Se determinaron las concentraciones de acetato, propionato y butirato usando la técnica de High Performance Liquid Cromatography " HPLC " con una columna de Aminex HPX-87H y ácido sulfúrico 0.01 mol/l en la fase móvil, (Hartemink et al., 1997). El análisis estadístico de los parámetros de cinética de producción de gas y AGVs se realizó por medio de un análisis de varianza de acuerdo con el Diseño Experimental empleado (Stell y Torrie, 1980), usando el procedimiento de GLM de SAS 8.02 (SAS inc., Cary, NC, USA) con el siguiente modelo lineal: ...
COMPENDIO Se estudió el efecto prebiótico del derivado de la lactosa (DL) en la población microbiana presente en las muestras de heces (inóculo fecal) de los cerdos posdestete. Se utilizó la técnica de producción de gas in vitro en 2 sustratos: el control pulpa de remolacha (PR) y DL. Se desarrollaron dos etapas. En la primera se determinó la producción del gas y las proporciones de ácidos grasos volátiles (AGV), evaluando la actividad microbiana en los niveles (0, 0.2, 2, 20 y 100%) de DL reemplazando a la PR, durante la fermentación de 144h. El tiempo medio de la producción del gas potencial se alcanzó a las 12h de la fermentación. Este tiempo se utilizó para la segunda etapa con tres niveles de DL (0, 20 y 100%). Se determinó el efecto del DL sobre la composición de la población microbiana (E. coli, lactobacillus y anaerobios facultativos totales), concentración de AGV y sobre el pH, como resultado de la fermentación bacteriana . Se incrementó la concentración del butirato (P < 0.001) y la acidificación (P < 0.001) del medio. El DL modificó la composición microbiana, que se reflejó en la disminución (P < 0.001) del número de colonias microbianas de E. coli. En conclusión el DL en niveles altos presentó efectos prebióticos. Palabras claves: Lactosa, prebiótico, fermentación in vitro, cerdo, butirato, Escherichia coli ABSTRACT Effect of Lactose Derivative (LD) on the present microbial populations in the sample faeces of weaned piglets The prebiotic effect of Lactose Derivative (LD) on the present microbial populations in the sample faeces (faecal inocula) of weaned piglets was studied . The in vitro gas-production technique was used. Using 2 substrates: sugarbeet pulp (SBP) as control and LD as evaluation. Two stages were developed. In the first it the gas production and the Volatile Fatty Acids (VFA) proportions, during 144h fermentation, to evaluate the effect of the microbial activity with different DL levels (0, 0.2, 2, 20 y 100%), as replacement to SBP was determined. The half time gas production potential, was reached at the 12h of fermentation. This time was used for the second stage and the DL levels (0, 20 and 100%). Microbial populations composition (E. coli, Lactobacillus and total facultative Anaerobes), VFA concentration and pH was determined. Effects of the DL were presented on the products of the bacterial fermentation in faecal inocula. An increment in 1 Artículo derivado de la Tesis de Maestría en Producción Animal Tropical. REC.: 22-08-2005 ACEPT.: 02-12-2005 2 Zoot. MSc. Calle19 #44ª-100 Pasto (Colombia).
O objetivo deste trabalho foi estudar a influência de parâmetros reacionais na obtenção via enzimática de galacto-oligossacarídeos (GOS), utilizando-se a enzima comercial β-galactosidase de Kluyveromyceslactis (Lactozym® 3000L), tendo como substrato a lactose. Foi proposto um planejamento experimental 23, verificando a influência da temperatura (30 a 40°C), da concentração de lactose (200 a 400mg.mL-1) e da concentração de enzima (5 a 10U.mL-1) no desempenho da reação enzimática. Os ensaios foram conduzidos a 180rpm e pH 7,0 (tampão fosfato de sódio 0,1M). A enzima Lactozym® 3000L apresentou atividade de transgalactosilação, tendo sido atingido rendimento do processo igual a 41,9% e concentração de GOS de 167,5mg.mL-1 no sistema reacional composto por 400mg.mL-1 de lactose e 5U.mL-1 de enzima a 30°C em 14h de reação. Nessa condição, a conversão de lactose foi de 65,0%. Maior concentração de lactose foi favorável ao mecanismo de transgalactosilação, enquanto que, em menores concentrações, o mecanismo hidrolítico predominou.
Galacto-oligosaccharides (GOS) have now been definitely established as prebiotic ingredients after in vitro and animal and human in vivo studies. Currently, GOS are produced by glycoside hydrolases (GH) using lactose as substrate. Converting lactose into GOS by GH results in mixtures containing GOS of different degrees of polymerization (DP), unreacted lactose, and monomeric sugars (glucose and galactose). Recent and future developments in the production of GOS aim at delivering purer and more efficient mixtures. To produce high-GOS-content mixtures, GH should not only have good ability to catalyze the transgalactosylation reaction relative to hydrolysis, but also have low affinity for the GOS formed relative to the affinity for lactose. In this article, several microbial GH, proposed for the synthesis of GOS, are hierarchized according to the referred performance indicators. In addition, strategies for process improvement are discussed. Besides the differences in purity of GOS mixtures, differences in the position of the glycosidic linkages occur, because different enzymes have different regiochemical selectivity. Depending on oligosaccharide composition, GOS products will vary in terms of prebiotic activity, as well as other physiological effects. This review focuses on GOS production from synthesis to purification processes. Physicochemical characteristics, physiological effects, and applications of these prebiotic ingredients are summarized. Regulatory aspects of GOS-containing food products are also highlighted with emphasis on the current process of health claims evaluation in Europe.
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