Colour assessment on bread wheat and triticale fresh pasta

Although durum wheat is the cereal of choice for pasta production, in many areas of Argentina pasta is made from bread wheat, since durum wheat is cultivated only in a small region of the country. The purpose of this work was to determine the influence of different bread flours on the colour of laminated fresh pasta. Triticale flour was also studied. In addition, ash, protein, and protein fractions of each flour were measured. Also, the formulation was modified using different gluten, starch, and water concentrations. Pasta lightness and redness were affected mainly by the ash content, while yellowness was affected by the protein content of different flours. A similar effect was found when the formulation was substituted for starch and gluten, due to protein dilution and concentration, respectively. Albumins and globulins correlated with a* component, while gliadins, soluble and insoluble glutenins correlated with b* component; however, only glutenins presented correlation with colour score (CS = [L* + (b*×2)]/20). The greatest amount of water added to the dough produced a decrease of lightness and an increase of redness and yellowness of pasta samples. The overall ANOVA revealed that the greatest sources of variation for pasta colour were the different flours used, in comparison with the effect of starch and gluten substitution, and with the addition of different amounts of water.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Colour assessment on bread wheat and triticale fresh pasta

Although durum wheat is the cereal of choice for pasta production, in many areas of Argentina pasta is made from bread wheat, since durum wheat is cultivated only in a small region of the country. The purpose of this work was to determine the influence of different bread flours on the colour of laminated fresh pasta. Triticale flour was also studied. In addition, ash, protein, and protein fractions of each flour were measured. Also, the formulation was modified using different gluten, starch, and water concentrations. Pasta lightness and redness were affected mainly by the ash content, while yellowness was affected by the protein content of different flours. A similar effect was found when the formulation was substituted for starch and gluten, due to protein dilution and concentration, respectively. Albumins and globulins correlated with a* component, while gliadins, soluble and insoluble glutenins correlated with b* component; however, only glutenins presented correlation with colour score (CS = [L* + (b*×2)]/20). The greatest amount of water added to the dough produced a decrease of lightness and an increase of redness and yellowness of pasta samples. The overall ANOVA revealed that the greatest sources of variation for pasta colour were the different flours used, in comparison with the effect of starch and gluten substitution, and with the addition of different amounts of water.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Efecto de los parámetros del proceso de extracción por prensado sobre el rendimiento y la calidad de aceite de Pistacho

Pistachio nuts have high economical and nutritional value, mostly due to their elevated oil con­tent (50%), which is composed mainly of oleic and linoleic fatty acids. Box-Behnken experimental designs were performed to optimize the oil extraction by response surface analysis. The independent variables measured were seed moisture content (SMC), restriction die (RD), screw press speed (PS) and pressing temperature (PT), while the response variables considered were oil recovery (OR), fine solid contents in the oil (FSC), oil remain­ing in the cake (OC) and parameters related to oil quality (free fatty acid composition (FFAC, mg KOH/g oil), peroxide value (PV, meq O2/kg oil), K232, K270 and pigment contents, mg/kg oil). Given that the chemical quality of pistachio nut oil pressed under different conditions was not affected, the process response was optimized in order to maximize OR under two pressing temperatures. Therefore, at 75 °C, pistachio oil extraction showed a maximum OR (79.61 g/100 g oil) at 8% SMC, 4 mm RD and 20 rpm SP; while, under cold-pressed conditions, the maximum OR (65.97 g/100 g oil) was achieved at 10% SMC, 4mm RD and 20 rpm SP. It is important to highlight that OR values were higher than the results reported previously and the chemical quality parameters from both oils were in the range of Codex standards for virgin (non-refined) oils (FFAC < 0.31 and PV < 0.33).Los frutos de pistacho son altamente nutritivos, principalmente debido a su contenido de aceite (50%), compuesto principalmente por ácidos grasos mono y di-insaturados. Con la finalidad de conocer las condiciones de proceso adecuadas que permitan maximizar la cantidad de aceite extraído preservando la calidad química del mismo se utilizaron dos diseños experimentales de Box-Behnken. Las variables independientes analizadas fueron la humedad de la semilla (HS), el diámetro de reducción (DR), la velocidad y temperatura de prensado (VP y TP, respectivamente), mientras que las variables de respuesta fueron el rendimiento en aceite (RA), el contenido de sólidos finos en el aceite (CFA), el aceite remanente en torta (AT) y parámetros relacionados con la calidad (composición en ácidos grasos libres (CAGL, mg KOH/g aceite), índice de peróxido (IP, meqO2/kg aceite), K232, K270 y pigmentos (mg/kg aceite)). La calidad química de los aceites obtenidos no mostró daño oxidativo y/o hidrolítico significativo bajo las diferentes condiciones del proceso (IP< 0.33 y CAGL< 0.31, respectivamente), por lo tanto, la respuesta se optimizó para maximizar RA a dos TP, 75 y 40 °C. El rendimiento en aceite se maximizó ajustando HS (8% ó 10% b.h.), DR (4 mm), VP (20 rpm) a ambas temperaturas, alcanzando extracciones de aceite de 79.61% y 65.97%, respectivament

Efecto de distintos oxidantes sobre la calidad de panes elaborados por el método tradicional argentino

La metodología de panificación tradicional argentina se destaca por utilizar escasa levadura y realizar fermentaciones muy largas, utilizando como oxidante bromato de potasio. Con la prohibición del uso de bromato desde el año 1998,cobró importancia el análisis de la acción de distintos oxidantes en estos procesos.En el presente trabajo se estudió la acción de 5 oxidantes sobre la retención de gases, el volumen de pan, las propiedades reológicas, la estructura de la miga y las interacciones entre proteínas. Los resultados de las electroforesis muestran que los oxidantes favorecen la formación de agregados proteicos, lo que estaría indicando el establecimiento de puentes disulfuro a partir de grupos sulfhidrilo. También se observa que ninguno de los aditivos en estudio puede suplantar por sí solo al bromato de potasio en este tipo de panificación, siendo la azodicarbonamida el oxidante que tiene el comportamiento más simila

Colour assessment on bread wheat and triticale fresh pasta

Although durum wheat is the cereal of choice for pasta production, in many areas of Argentina pasta is made from bread wheat, since durum wheat is cultivated only in a small region of the country. The purpose of this work was to determine the influence of different bread flours on the colour of laminated fresh pasta. Triticale flour was also studied. In addition, ash, protein, and protein fractions of each flour were measured. Also, the formulation was modified using different gluten, starch, and water concentrations. Pasta lightness and redness were affected mainly by the ash content, while yellowness was affected by the protein content of different flours. A similar effect was found when the formulation was substituted for starch and gluten, due to protein dilution and concentration, respectively. Albumins and globulins correlated with a* component, while gliadins, soluble and insoluble glutenins correlated with b* component; however, only glutenins presented correlation with colour score (CS = [L* + (b*×2)]/20). The greatest amount of water added to the dough produced a decrease of lightness and an increase of redness and yellowness of pasta samples. The overall ANOVA revealed that the greatest sources of variation for pasta colour were the different flours used, in comparison with the effect of starch and gluten substitution, and with the addition of different amounts of water.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Características tecnológicas de almidones de dos variedades de batatas (Ipomoea batatas [L.] Lam) infectadas con «encrespamiento amarillo»

El cultivo de batata se ve limitado por virosis y un complejo de siete virus, «encrespamiento amarillo» (EA), de alta incidencia en Argentina, provoca significativas disminuciones de rendimiento y calidad. En un ensayo experimental, con variedades Arapey INIA y Beauregard (sanas y enfermas con EA), se estimaron componentes de rendimiento (principalmente peso: PRC y número: NRC de raíces comerciales), rendimiento y característicastecnológicas de almidón como gelatinización y retrogradación (calorimetría diferencial de barrido) y viscosidad aparente de las pastas (analizador de viscosidad). Se analizó el comportamiento reológico de los geles de almidón, mediante resistencia a la compresión con analizador de textura, y se determinó distribución de tamaño de partícula. NRC y PRC fueron significativamente menores en plantas enfermas respecto a sanas (mermas de 81% para NRC en ambas variedades y 87% y 85,5% para PRC, en Beauregard y Arapey, respectivamente). EA no afectó al rendimiento de almidón, sin diferencias entre raíces sanas y enfermas de ambas variedades, aunque Arapey (9,00-10,05%) superó a Beauregard (6,23-8,06%). La entalpía de gelatinización del almidón resultó significativamente mayor en plantas enfermas de Beauregard que en sanas, sin diferencias en la temperatura de inicio de gelatinización entre ambos tratamientos, contrariamente a lo que sucedió en Arapey. El pico de viscosidad y la viscosidad final de los almidones fueron similares en plantas sanas y enfermas de ambas variedades, igual que la resistencia a la compresión de geles elaborados con almidones provenientes de plantas sanas y enfermas de ambos genotipos. Todas las muestras tuvieron una sola población de tamaño de partícula de almidón (rango: 5 -25 μm con pico cercano a 15 μm). En definitiva, EA no afectó la calidad tecnológica del almidón. Sin embargo, la disminución significativa de producción de raíces comerciales en plantas enfermas conllevó relevante reducción de la cantidad total de almidón por planta

The electrochemistry of nanostructured Ni–W alloys

This work reports on the features that Ni–W nanostructured alloys, electrodeposited on carbon steel by different current pulse programs, may present depending on their surface morphology and surface composition. The Ni–W nanostructured coating, with a cauliflower structure, lack of fragility, and high WO3/W surface composition ratio, is a stable electrode to catalyze hydrogen evolution reaction, exceeding bulk and electrodeposited Ni catalytic activity. Also, the nanostructured alloys must have a low WO3/W surface composition ratio for Ni and its oxides to provide protection and improve corrosion resistance in sulfate media.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Morphological stabilization and KPZ scaling by electrochemically induced co-deposition of nanostructured NiW alloy films

We have assessed the stabilizing role that induced co-deposition has in the growth of nanostructured NiW alloy films by electrodeposition on polished steel substrates, under pulsed galvanostatic conditions. We have compared the kinetic roughening properties of NiW films with those of Ni films deposited under the same conditions, as assessed by Atomic Force Microscopy. The surface morphologies of both systems are super-rough at short times, but differ at long times: while a cauliflower-like structure dominates for Ni, the surfaces of NiW films display a nodular morphology consistent with more stable, conformal growth, whose height fluctuations are in the Kardar-ParisiZhang universality class of rough two-dimensional interfaces. These differences are explained by the mechanisms controlling surface growth in each case: mass transport through the electrolyte (Ni) and attachment of the incoming species to the growing interface (NiW). Thus, the long-time conformal growth regime is characteristic of electrochemical induced co-deposition under current conditions in which surface kinetics is hindered due to a complex reaction mechanism. These results agree with a theoretical model of surface growth in diffusion-limited systems, in which the key parameter is the relative importance of mass transport with respect to the kinetics of the attachment reaction.We acknowledge financial support from ANPCyT (PICT 2012-1808), CONICET (PIP 0671) and Universidad Nacional de La Plata (11X760) as well as from MINECO/FEDER (Spain/UE) Grants MAT2014-54231-C4-1-P, FIS2015-66020-C2-1-P and MAT2014-52405-C2-2-R, as well as by Comunidad Autónoma de Madrid (Spain) Grant NANOAVANSENS S2013/MIT-3029. M.E.V. is member of the research career of CICPB

Morphological stabilization and KPZ scaling by electrochemically induced co-deposition of nanostructured NiW alloy films

We have assessed the stabilizing role that induced co-deposition has in the growth of nanostructured NiW alloy films by electrodeposition on polished steel substrates, under pulsed galvanostatic conditions. We have compared the kinetic roughening properties of NiW films with those of Ni films deposited under the same conditions, as assessed by Atomic Force Microscopy. The surface morphologies of both systems are super-rough at short times, but differ at long times: while a cauliflower-like structure dominates for Ni, the surfaces of NiW films display a nodular morphology consistent with more stable, conformal growth, whose height fluctuations are in the Kardar-Parisi- Zhang universality class of rough two-dimensional interfaces. These differences are explained by the mechanisms controlling surface growth in each case: mass transport through the electrolyte (Ni) and attachment of the incoming species to the growing interface (NiW). Thus, the long-time conformal growth regime is characteristic of electrochemical induced co-deposition under current conditions in which surface kinetics is hindered due to a complex reaction mechanism. These results agree with a theoretical model of surface growth in diffusion-limited systems, in which the key parameter is the relative importance of mass transport with respect to the kinetics of the attachment reaction.Facultad de Ciencias Exacta

Modulated structures in electroconvection in nematic liquid crystals

Motivated by experiments in electroconvection in nematic liquid crystals with homeotropic alignment we study the coupled amplitude equations describing the formation of a stationary roll pattern in the presence of a weakly-damped mode that breaks isotropy. The equations can be generalized to describe the planarly aligned case if the orienting effect of the boundaries is small, which can be achieved by a destabilizing magnetic field. The slow mode represents the in-plane director at the center of the cell. The simplest uniform states are normal rolls which may undergo a pitchfork bifurcation to abnormal rolls with a misaligned in-plane director.We present a new class of defect-free solutions with spatial modulations perpendicular to the rolls. In a parameter range where the zig-zag instability is not relevant these solutions are stable attractors, as observed in experiments. We also present two-dimensionally modulated states with and without defects which result from the destabilization of the one-dimensionally modulated structures. Finally, for no (or very small) damping, and away from the rotationally symmetric case, we find static chevrons made up of a periodic arrangement of defect chains (or bands of defects) separating homogeneous regions of oblique rolls with very small amplitude. These states may provide a model for a class of poorly understood stationary structures observed in various highly-conducting materials ("prechevrons" or "broad domains").Comment: 13 pages, 13 figure