Purificación de lecitina de soja. 1-Selección de equipamiento y determinación de las condiciones operativas. 2-Obtención de diagrama de equilibrio

In this work we describe the choice of the best operating conditions to produce pure powder soybean lecithin, extracting with acetone, in a bench scale. The equipment was designed in order to obtain adequate impeller and turbine systems response because there is significant viscosity variations between batches, and the extraction process was difficult. By operating in these conditions, we have obtained the equilibrium values for the phospholipids/oil/acetone mixture. The results showed that there are a phospholipids/oil interaction and this might be by solute absorption or because the solute is soluble in the solid and it is no reparting by equal between the equilibrium liquid and solid phases.En el presente trabajo se describe la selección de las condiciones operativas óptimas para la purificación de lecitina de soja, utilizando acetona y operando en discontinuo. El equipo se diseñó teniendo en cuenta que se producía una gran variación de la viscosidad que dificultaba la extracción, por lo que se debió prestar especial atención al diseño del sistema impulsor y del sistema agitador. Operando bajo estas condiciones se obtuvieron los valores de equilibrio para la mezcla fosfolípidos/aceite/acetona. Los resultados evidencian interacción entre los fosfolípidos y el aceite, bien porque habría absorción preferente de soluto o bien porque el soluto es soluble en el sólido y no se distribuye por igual entre las fases líquidas y sólidas en el equilibrio

La construcción de nociones básicas de química en ciencias agropecuarias : el caso de "efectos electrónicos en las moléculas"

La comprensión de la relación estructura-propiedades es fundamental en el estudio de química en las ciencias agropecuarias. En ese sentido y a partir de las dificultades observadas en los alumnos para la aplicación de ese núcleo conceptual, se identificó la noción básica efectos electrónicos en las moléculas y se planteó la investigación de su construcción conceptual. Se utilizaron en este estudio dos instrumentos metodológicos: cuestionario y entrevista semiestructurada con modalidad clínica. Se detectaron ciertos obstáculos epistemológicos en la argumentación de los alumnos. Éstos fueron: la tendencia a la generalización, el empirismo inmediato y los modelos simplistas, que actuarían bloqueando el pensamiento profundo. Concluímos que el aprendizaje de la noción efectos electrónicos en las moléculas requiere del despliegue de toda su complejidad epistemológica.The understanding of the structure-properties relation is of great importance in the chemistry study in Agricultural Sciences. In this sense, starting from the difficulties found in students when applying this conceptual nucleus, we identified the basic notion molecular electronic effects and proposed the research of its conceptual construction. In this study, two methodologies were applied: questionnaire and clinical semistructured interview. The answers and the arguments of the students showed certain epistemological obstacles. These were: the tendency to generalization, the immediate empiricism and the simplistic models that would act blocking the profound thoughts. We concluded that the learning of the notion: molecular electronic effects needs to display its overall epistemological complexity

Emulsifying Properties of Different Modified Sunflower Lecithins

Lecithins are a mixture of acetone-insoluble phospholipids and other minor substances (triglycerides, carbohydrates, etc.). The most commonly processes used for lecithin modification are: fractionation by deoiling to separate oil from phospholipids, fractionation with solvents to produce fractions enriched in specific phospholipids, and introduction of enzymatic and chemical changes in phospholipid molecules. The aim of this work was to evaluate the emulsifying properties of different modified sunflower lecithins in oil-in-water (O/W) emulsions. In this study, five modified sunflower lecithins were assessed, which were obtained by deoiling (deoiled lecithin), fractionation with absolute ethanol (PC and PI enriched fractions), and enzymatic hydrolysis with phospholipase A2 from pancreatic porcine and microbial sources (hydrolyzed lecithins). Modified lecithins were applied as an emulsifying agent in O/W emulsions (30:70 wt/wt), ranging 0.1–2.0% (wt/wt). Stability of different emulsions was evaluated through the evolution of backscattering profiles (%BS), particle size distribution, and mean particle diameters (D [3, 4], D [3, 2]). PC enriched fraction and both hydrolyzed lecithins presented the best emulsifying properties against the main destabilization processes (creaming and coalescence) for the analyzed emulsions. These modified lecithins represent a good alternative for the production of new bioactive agents.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Application of Enzymatic Hydrolysis on Sunflower Lecithin Using a Pancreatic PLA2

The aim of the present investigation was to evaluate the influence of the main operating conditions on the application of an enzymatic hydrolysis on sunflower lecithin at laboratory scale. This study seeks to contribute to the oil industry with useful information for rescaling this modification process, in order to increase the value-added of sunflower lecithins.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Early detection of left ventricular diastolic dysfunction in Chagas' disease

BACKGROUND: Chagas' disease may cause left ventricular diastolic dysfunction and its early detection in asymptomatic patients would allow to stratify the risk and to optimize medical treatment. The aim of this study is to investigate if transmitral Doppler flow can detect early abnormalities of the diastolic left ventricular function in patients during the indeterminate phase of Chagas' disease, in which the electrocardiogram (ECG), chest x-ray and 2-D echocardiogram (2D-echo) are normal. METHODS: a group of 54 patients with Chagas' disease was studied and compared to a control group of 27 subjects of similar age. All were assessed with an ECG, chest X-ray, 2-D echo, and transmitral Doppler flow. RESULTS: both groups had similar values in the 2D-echo. In patients with Chagas' disease, the transmitral Doppler showed a higher peak A velocity (control group: 0.44 m/sec, Chagas group: 0.55 m/sec, p = 0.001), a lower E/A ratio (control group: 1.45, Chagas group: 1.22, p < 0.05), and a lengthening of the deceleration time of early diastolic filling (control: 138.7 ± 26.8 msec, Chagas group: 167.9 ± 34.6 msec, p = 001), thus revealing an early disorder of the diastolic left ventricular function in patients with Chagas' disease. CONCLUSION: in patients with Chagas' disease who are in the indeterminate phase, transmitral Doppler flow allowed to identify early abnormalities of the left ventricular diastolic function, which provide useful clinical information for prognostic stratification and treatment

Obtaining and use of sunflower hydrolyzed lecithins in oil/water (O/W) emulsions

Las lecitinas son una mezcla compleja de fosfolípidos -principalmente fosfatidilcolina (PC), fosfatidiletanolamina (PE), fosfatidilinositol (PI)-, glicolípidos, carbohidratos y aceite. Si bien las lecitinas de soja lideran el mercado, el empleo de las lecitinas de girasol podría representar una alternativa interesante dado que son un producto no GMO y poseen rangos similares en la distribución de sus fosfolípidos mayoritarios. La introducción de cambios en la concentración relativa de estos componentes, mediante procesos de hidrólisis enzimática, puede originar lecitinas modificadas de mayor funcionalidad para la manufactura de diversos productos (margarinas, productos de panadería y emulsiones alimentarias). El objetivo de este trabajo fue investigar la aplicación de lecitinas hidrolizadas de girasol como agente emulsificante en sistemas O/W. Para ello, la lecitina nativa de girasol fue sometida a una hidrólisis enzimática utilizando una fosfolipasa A2 (Lecitase 10 L, Novo Nordisk). El proceso de hidrólisis se llevó a cabo -a escala laboratorio- en un reactor termostatizado con agitación continua (50 rev/min) a 60 ºC, 5 h. Se colocaron 27 g de lecitina, 18 ml de CaCl2 0.4 M y 0,54 ml de la enzima ajustando el pH inicial a 7 y 9, respectivamente, con eliminación posterior del aceite residual (deoiling). Las lecitinas hidrolizadas fueron utilizadas en la formulación de emulsiones O/W (30:70 p/p) en un rango de concentraciones de 0,1 - 2.0% con respecto a la fase acuosa, mediante la homogeneización en Ultraturrax T25 (10.000 rpm, 1 min). Por otra parte, lecitina hidrolizada de soja (Solec K-EML, Solae Company) y lecitina nativa de girasol sin aceite, fueron utilizadas en las mismas condiciones con fines comparativos, estudiando la estabilidad de las distintas emulsiones mediante su caracterización óptica en función del tiempo con un analizador vertical de barrido (Quick Scan). Las emulsiones obtenidas con lecitinas hidrolizadas a pH 7 y 9 (LH7 y LH9) presentaron un aumento de su estabilidad hasta niveles de concentración de 0,5%, disminuyendo levemente esta capacidad –en ambos casos- entre 1 - 2%. Estas emulsiones exhibieron diferencias altamente significativas (p < 0,01) en este parámetro con respecto a las obtenidas con lecitina nativa de girasol en todas las concentraciones estudiadas. Con respecto a la lecitina hidrolizada de soja, no presentaron diferencias a niveles de concentraciones 0,1 – 0,5%, aunque ciertas diferencias se evidenciaron a mayores concentraciones. La conversión de fosfolípidos a lisofosfolípidos por hidrólisis enzimática así como el aumento del balance hidrofílico-lipofílico (HLB) serían los responsables del aumento del poder emulsificante asociado a las lecitinas hidrolizadas obtenidas frente a la lecitina nativa de girasol, lo cual les confiere una alta potencialidad como emulsificante a nivel industrial.Lecithins are a complex mixture of phospholipids – mainly phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI)-, glycolipids, carbohydrates and oil. Although soybean lecithins are leader of the market, the use of sunflower lecithins could be an interesting alternative because they are non-GMO products and the distribution of their main phospholipids is similar to soybean lecithins. The introduction of changes in the relative concentration of these compounds by enzymatic hydrolysis, can originate modified lecithins with a high functionality, which could be used for the manufacturing of several products (margarines, bakery products, food emulsions). The aim of this work was to investigate the application of sunflower hydrolysed lecithins as emulsifying agent in O/W systems. Native Sunflower lecithin was used asa a substrate of enzymatic hydrolysis using an A2 phopholipase (Lecitase 10 L, Novo Nordisk). The hydrolysis process was carried out –at a laboratory scale- in a thermostatized reactor with continuous agitation (50 rpm) at 60 ºC, 5 h Lecithin (27 g), CaCl2 0.4 M (18 ml) and the enzyme (0.54 ml) were placed in the reactor, adjusting the initial pH to 7 (LH7) and 9 (LH9), with a subsequent elimination of residual oil (deoiling). The hydrolysed lecithins were used in the formulation of O/W emulsions (30:70 w/w) in a range of concentrations (0.1 - 2.0% with respect to the aqueous phase) with the homogenization in an Ultraturrax T25 homogenizer (10,000 rpm, 1 min). On the other hand, soybean hydrolysed lecithin (Solec K-EML, Solae Company) and native sunflower lecithin deoiled, were used in the same operative conditions, studying the stability of the different emulsions through their optical characterization time-dependent with a vertical scan analyzer (Quick Scan). The emulsions obtained with LH7 and LH9 showed an increase of their stability at 0.5%, with a slight decrease of this capacity –in both cases – between 1 – 2%. These emulsions showed highly significant differences (p &lt; 0.01) in this parameter with respect to those obtained with native sunflower lecithin in all concentrations studied. Regarding soybean hydrolysed lecithin, significant differences (p &lt; 0.01) were found at concentrations greater than 0.5% but not in the range of 0.1 – 0.5% (p &gt; 0.05).The conversion of phospholipids to lisophospholipids by enzymatic hydrolysis and the increase of the hydrophilic – lipophilic balance (HLB) would be the responsible of the high emulsifying properties of the hydrolysed lecithins with respect to the native sunflower lecithins, which gives a high potential as an emulsifier to industrial scale.Centro de Investigación y Desarrollo en Criotecnología de Alimento

DtnSim: Bridging the Gap Between Simulation and Implementation of Space-Terrestrial DTNs

International audienc

Internetworking Approaches Towards Along-Track Segmented Satellite Architectures

International audienceThe Argentinian Space Agency (CONAE) has beenpursuing the development of segmented satellite architectures asa novel strategy to reduce the cost and improve responsivenessof space access. Among the key enablers for these architectures,wireless communication is likely to be the most critical as itrequires to operate on a highly dynamic, sparse and extremeenvironments. In this work, we analyze and derive the mainspecifications that a communication system for segmented architectures(CSSA) must support. In particular, we provide anabstract model to predict the access time to segmented systems tolater propose a layered arrangement of the main specificationsfor the CSSA. Finally, we analyze by simulation a particularCSSA configuration in a simple yet representative scenario withan along-track flight formation