The objective of the present work was to evalúate the effect of different factors on the extraction of pectin from lemon albedo, using the enzymatic extract with polygalacturonase activity of Wickerhamomyces anomalus (WA strain 110), a native yeast from the Province of Misiones, Argentina. Pectin extraction process was carried out in Erlenmeyer flasks containing lemon albedo, buffer and the crude enzymatic extract of WA strain 110, with agitation (pH 5.0). Factors studied were: solid-liquid ratio, temperature, time and enzyme activity. The soluble polymeric material was precipitated with ethanol and the weight of the dried gel obtained was named as ethanol insoluble material (EIM). It was obtained a yield of MlE of 35.93± 0.67% (w/w), with a solid / liquid ratio of 1/50, 12.5 mL of EE (PGase activity in the reaction médium: 4.28 UE/mL), 40° C, 4 h, and pH 5.0. This valué was higher than that obtained using the chemical method, which confirms the goodness of the enzymatic process used.

El objetivo del presente trabajo fue evaluar el efecto de diferentes factores en la extracción de pectina a partir de albedo de limón, mediante el extracto enzimático con actividad poligalacturonasa de Wickerhamomyces anomalus (WA cepa 110), una levadura autóctona de la provincia de Misiones, Argentina. El proceso de extracción enzimática de pectina se realizó en frascos Erlenmeyers conteniendo albedo de limón, buffer y el extracto enzimático crudo de WA cepa 110, con agitación (pH 5,0). Los factores evaluados fueron: relación sólido/líquido, temperatura, tiempo y actividad enzimática. El material polimérico se precipitó con etanol y el peso seco del gel obtenido se denominó material insoluble en etanol (MIÉ). Se obtuvieron rendimientos de MIÉ de 35,93±0,67% (p/p), con una relación sólido/líquido de 1/50, 12,5 mL del EE (actividad PGasa en el medio de reacción: 4,28 UE/mL), 40° C, 4 h y pH 5,0. Este valor fue superior al obtenido utilizando el método químico, lo cual confirma la bondad del proceso enzimático utilizado.

The objective of the present research was to evaluate the effect of the cultivation conditions on the production of a polygalacturonase (PGase) by Wickerhamomyces anomalus. Fermentations were carried out in agitated flasks, in a synthetic medium, varying culture conditions (temperature, pH and agitation). A 2³ factorial design was initially applied and then response surface methodology. The macerating capacity of the enzymatic extract on a vegetal tissue was evaluated. PH and temperature significantly influenced the production of PGase enzyme, while the influence of the stirring rate was not significant. The highest titles were obtained at 30°C and pH of 5.1; with a maximum PGase activity of 18.84 EU / mL. The enzymatic extract was able to macerate bell pepper tissues. Enzymatic extracts with high PGase activity were obtained, under selected conditions, of interest in food technology.

El objetivo del presente trabajo fue evaluar el efecto de las condiciones de cultivo sobre la producción de una Poligalacturonasa (PGasa) por Wickerhamomyces anomalus. Las fermentaciones se realizaron en frascos agitados, en un medio sintético, variando las condiciones de cultivo (temperatura, pH y velocidad de agitación). Se aplicó inicialmente un diseño factorial 2³ y posteriormente la metodología de superficie de respuesta. Se evaluó la capacidad macerante del extracto enzimático sobre un tejido vegetal. El pH y la temperatura influyeron significativamente en la producción de la enzima PGasa, mientras que la influencia de la velocidad de agitación fue no significativa. Los mayores títulos se obtuvieron a 30° C y pH de 5,1; con un valor máximo de actividad PGasa de 18,84 UE/mL. El extracto enzimático fue capaz de macerar tejidos de pimiento morrón. Se obtuvieron extractos enzimáticos con elevada actividad PGasa, en las condiciones seleccionadas, de interés en tecnología de los alimentos.

Pasta consumption is massive and there is no variety in premixes for gluten-free noodles. The objective of this work was to evaluate the chemical characteristics of noodles made from a premix for cassava starch, corn meal, milk, salt and xanthan gum; and its shelf life. In order to know the centesimal composition and the digestibility of proteins we used elaborate and cooking noodles. Premix bags were packaged for the shelf life and analyzed for 12 months of storage at room temperature and humidity. High values of ash, fat, total dietary fiber and carbohydrates, and low protein levels were obtained; the protein digestibility was 92.72%. The ANOVA reported a significant difference for humidity at different months, with a decrease in time; no microorganisms of health interest were detected. The premix was suitable for human consumption according to Argentine Food Code.

El consumo de pastas es masivo, no existiendo variedad en premezclas para fideos libres de gluten. El objetivo del trabajo fue evaluar caracteristicas quimicas de fideos elaborados a partir de una premezcla para pastas con fecula de mandioca, harina de maiz, leche, sal y goma xantica; y la vida util en anaquel de la misma. Para conocer la composicion centesimal y la digestibilidad de proteinas se recurrio a elaboracion y coccion de fideos; para la vida util se empaquetaron bolsas de premezcla y analizaron durante 12 meses de almacenamiento a temperatura y humedad ambiente. Se obtuvieron valores elevados de cenizas, grasas, fibra dietaria total y carbohidratos, y bajos de proteinas; la digestibilidad de proteinas fue 92,72%. El ANOVA reporto diferencia significativa para humedad a los diferentes meses, con disminucion en el tiempo; no se detectaron microorganismos de interes sanitario. La premezcla resulto apta para consumo humano segun Codigo Alimentario Argentino.

The objective of the present work was to determine the predictive ability of Pilosof and exponential models to describe water absorption kinetics of cassava tissues macerated with the enzymatic extract of Wickerhamomycesanomalus. Cassava tissues were macerated in Erlenmeyers flasks at 45 oC, on a rotator shaker (190 rpm), during 1,2 and 4 h, with different extract enzymatic dilutions. Macerated cassava tissues were filtered and dried. A good fit of the experimental data to water absorption models evaluated was obtained. The highest value of C∞ (water concentration at equilibrium) was reached at 1 h of maceration, using undiluted enzymatic extract, with a lower cell damage respect to longer treatments. At higher enzymatic treatment times, water absorption rate constant (K) increased, but C∞ decreased.

El objetivo del presente trabajo fue determinar la capacidad predictiva de los modelos de Pilosof y Exponencial, para describir la cinetica de absorcion de agua de tejidos de mandioca macerados con el extracto enzimatico de Wickerhamomycesanomalus. Los tejidos de mandioca fueron macerados en frascos erlenmeyers, a 45 oC, en agitador rotatorio (190 rpm), durante 1, 2 y 4 h, utilizando diferentes diluciones del extracto enzimatico. El tejido macerado fuefiltrado y secado.Se obtuvo un buen ajuste de los datos experimentales a los modelos de absorcion de agua evaluados. El mayor valor de C∞ (concentracion de agua en el equilibrio) se obtuvo a tiempos de maceracion de 1 h, utilizando extracto enzimatico sin diluir, con un menor dano celular respecto a los tratamientos efectuados a mayores tiempos. Al aumentar el tiempo del tratamiento enzimatico, la constante de velocidad de absorcion de agua (K) fue mayor, pero C∞ disminuyo.

The objective of the present study was the isolation of a yeast strain, from citrus fruit peels, able to produce a polygalacturonase by submerged fermentation with maceration activity of raw cassava roots. Among 160 yeast strains isolated from citrus peels, one strain exhibited the strongest pectinolytic activity. This yeast was identified as Wickerhamomyces anomalus by 5.8S-ITS RFLP analysis and confirmed by amplification of the nucleotide sequence. The yeast produced a polygalacturonase (PG) in Erlenmeyer shake flasks containing YNB, glucose, and citrus pectin. PG synthesis occurred during exponential growth phase, reaching 51 UE.mL-1 after 8 hours of fermentation. A growth yield (Yx/s) of 0.43 gram of cell dry weight per gram of glucose consumed was obtained, and a maximal specific growth rate (µm) of 0.346 h-1 was calculated. The microorganism was unable to assimilate sucrose, galacturonic acid, polygalacturonic acid, or citrus pectin, but it required glucose as carbon and energy source and polygalacturonic acid or citrus pectin as inducers of enzyme synthesis. The crude enzymatic extract of Wickerhamomyces anomalus showed macerating activity of raw cassava. This property is very important in the production of dehydrated mashed cassava, a product of regional interest in the province of Misiones, Argentina.

O objetivo deste estudo foi determinar a suscetibilidade de aeromonas de origem alimentar a carbapenems bem como investigar a presença de um gene codificante de metalocarbapenemase, denominado "cph A". A suscetibilidade in vitro foi determinada pelo metodo de diluição em agar. Todas as cepas foram suscetíveis a Imipenem, Meropenem e Biapenem. Porém foi observado um forte efeito de tamanho do inóculo sobre as CIM das carbapenems na maioria das cepas. A detecção de metalo-beta-lactamase foi realizada pelo metodo lodometrico. Seis cepas das sete testadas demostraron a presença da enzima. A presença do gene cphA foi determinada por PCR e foi detectada em duas cepas de A veronii bv. sobria.

The purpose of this study was to determine the susceptibilities of food-borne Aeromonas to carbapenems, as well as to investigate the presence of a metallo carbapenemase-encoding gene, named cphA. Minimum Inhibitory Concentration (MIC) was determined following NCCLS standards. All the tested microorganisms were susceptible to imipenem, meropenem and biapenem. However, a strong inoculum size effect on carbapenem MICs was observed for most of the strains. Six strains, out of seven, showed the presence of metallo--beta-lactamases but cphA gene was detected in only two strains of A. veronii bv. sobria.