Esta publicación científica en formato digital es continuidad de la revista impresa ISSN 0254-0770 / Depósito legal pp 197802ZU38Rev.
AbstractSome important chemical and thermal characteristics of components of fermented and dry Venezuelan Trinitario cocoa beans (Theobroma cacao L.) were determined. Average bean shell weight (as percent of whole bean weight) was 15.5%, with an average thickness 0.310 mm. Its moisture content (d.b.: dry basis) was significantly higher (p≤0.05) than that of whole and peeled beans. In spite of the shell higher moisture content, its water activity (a w ) was lower than that of peeled and whole beans, evidencing higher water binding capacity. Crude fat content (d.b.) was higher in whole beans than in peeled beans and significantly larger than that in shells. Crude protein content (d.b.) exhibited a decreasing order for whole beans, peeled beans and shells. The ash content (d.b.) was significantly higher in the shell than in whole and peeled beans. Cocoa bean constituents, exhibited similar thermal properties, as evidenced by their melting and pyrolysis behavior obtained by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) techniques.
Composición y Caracterización Termogravimétrica de los Componentes de Habas de Cacao Trinitario Venezolano (Theobroma cacao L.) Fermentado y Seco: Habas Enteras, Peladas y CascarillasResumen Se determinaron algunas características químicas y térmicas del cacao Trinitario venezolano (Theobroma cacao L.). El peso promedio de la cascarilla del haba de cacao (como porcentaje del peso del haba entera) fue del 15.5%, con un espesor promedio de 0.310 mm. Su contenido de humedad (b.s.: base seca) fue significativamente mayor (p≤0.05) que el de las habas enteras y sin cascarilla. A pesar de que la cascarilla tiene un mayor contenido de humedad, su actividad de agua (aw) fue menor que la de las habas enteras y sin cascarilla, lo que demuestra una mayor capacidad de adsorción de humedad. El contenido de grasa cruda (b.s.) fue mayor en habas enteras que en las habas sin cascarilla y significativamente mayor que en las cascarillas. Se encontró que el contenido de proteína (b.s.) disminuyó en el siguiente orden: habas enteras, habas sin cascarilla y cascarillas. El contenido de cenizas (b.s.) fue significativamente mayor en la cascarilla que en las habas enteras y sin cascarilla. Los constituyentes de las habas de cacao exhibieron propiedades térmicas similares, de acuerdo con los datos de fusión y pirólisis obtenidos mediante calorimetría diferencial de barrido (DSC) y técnicas de análisis termogravimétrico (TGA).Palabras clave: habas de cacao; cascarillas; actividad de agua; DSC; TGA.Rev.
The evaluation of glassy carbon (GC) electrodes modified with a Nafion (Nf) film and doped with nanoalloys (Nys) deposits of Ag–Hg and Ag–Bi and their application to determination of Cd (II) and Pb(II) in marine sediments, is described. Deposited Ag–Hg and AgBi Nys have a size of approximately ~80 nm dispersed and embedded inside the booths of the Nf net, while other of them remained on Nf net surface. For the AgBiNysNf-GC electrode, a detection limit (DL), 3 s criterion, slightly higher than for the AgHgNysNf-GC modified electrode was obtained. Accuracy of measurements was asserted by comparison with quantification of Cd and Pb in three sets of marine sediments samples previously analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The values of the standard deviation and the coefficients of variation are very low, and also comparable between the different determinations.
Germination is a process that involves changes in the enzymatic activity of grains and macromolecule breakdown, which decreases anti-nutritional factors and increases the synthesis of other constituents. Germinated grains are thus of higher sensory, nutritional and functional value. In this research, pigeon pea (Cajanus cajan) grains were germinated for 96 hours at 20ºC in the dark. Variations in proximal composition, fatty acids composition, antioxidant ability and mineral bioaccessibility were determined. The results obtained showed that because of the germination process, protein content decreased, while ash, fat and carbohydrate content increased. Fatty acid profile was determined and six fatty acids were identified, with the greatest amount of linoleic acid. The fatty acid content changed with the applied process. The polyphenolic content and antioxidant ability also increased as a result of the germination process. The values obtained for the mineral bioaccessibility varied from 16 to 31% for magnesium and potassium, respectively. It was concluded that pigeon pea grains represent a food of high nutritional value, which, as a result of germination, can create positive nutritional changes. Thus, consumption of this food should be promoted.
Presentamos la evaluación de los electrodos de carbono vítreo (GC) modificados con películas de Nafion (Nf) y depósitos bimetálicos de aleaciones Ag-Hg y Ag-Bi. La mayoría de los bimetálicos depositados, con un tamaño promedio de aproximadamente 150 nm, se dispersaron e incrustaron uniformemente dentro de la red del Nafion, mientras que una cantidad mucho menor permaneció encima de las incrustadas sin ninguna orientación regular, como lo indica imágenes de microscopía electrónica de barrido (SEM) y microscopía de fuerza atómica (AFM). Las pruebas de sensibilidad para el electrodo modificado AgBiNf/GC produjeron límites de detección (DL), basados en la variabilidad de una solución en blanco (criterio de 3 s), de 0,78 y 0,66 μg L-1 para Cd (II) y Pb (II), respectivamente; mientras que el DL sobre el electrodo modificado AgHgNf/GC fue 0,17 y 0,24 μg L-1 para Cd (II) y Pb (II), respectivamente. La precisión de la metodología por voltametría de redisolución anódica se verificó mediante el cálculo de porcentajes de recuperación de los dos analitos, expresados como error relativo. Se logró una recuperación del 99% al 92%.
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