No abstract

KeyWordsColumn liquid chromatography Postcolu mn derivatisation Sugars Carbohydrate-rich foods SummaryA method for the direct determination of carbohydrates in foods using an automated-flow system coupled on-line to a high-performance liquid chromatograph is proposed. The method is based on postcolumn clerivatisation of reducing sugars with p-aminobenzoic acid hyclrazide in an alkaline medium following elution from the chromatographic column with an acetonitrile:water graclient as mobile phase. The manifold allows non-reducing sugars to be hyclrolysed prior to insertion into the chromatograph, thus making them compatible with the clerivatisation reaction and with continuous clecolorisation of the sample on an activated carbon column. The method allows determination of six sugars in contents bef,,veen 0.005 and 4% (w/v) with high precision (3.8 -5.0% RSD). For analytical validation, it was applied to determination of fructose, sucrose, maltose, lactose and maltotriose in l",,vo reference materials (milk powder and sugar). Finally the method was used to determine sugars in a varie b, of carbohydrate-rich foods.

Determinación de antocianinas y capacidad antioxidante en extractos de (Muehlembeckia volcanica)Determination of anthocyanins and antioxidant capacity in extracts of (Muehlembeckia volcanica

Two hybrids, 'UPV-FA' and 'UPV-FMy', hereinafter 'Fian' and 'Fimy', were obtained by crossing the wild Cucumis species C. ficifolius with C. anguria and C. myriocarpus, respectively. These species are known to be resistant to nematodes. The hybrids have been tested against the main melon soil borne and aerial fungal pathogens. Both were highly resistant to Macrophomina phaseolina and to Fusarium oxysporum f. sp. melonis (Fom) race 1.2 (wilting isolate), and moderately resistant to Fom 1.2 (yellowing isolate) and to Monosporascus cannonballus. 'Fimy' was highly resistant to powdery mildew races 2 and 5, and 'Fian' was highly and moderately resistant to these races, respectively. These hybrids were previously evaluated as rootstocks for melon in greenhouses and experimental fields with good results (adequate compatibility, growth development and production, and no negative impact on fruit quality). This behaviour has been now confirmed in commercial fields. The same grafting combinations were used: as scion the muskmelon cv. 'Vendrantais', a Charentais type, and the cv. 'Finura', a Piel de Sapo type, and as rootstocks 'Fian', 'Fimy' and two commercial rootstocks 'Cobalt' (Cucumis maxima x Cucumis moschata) and '64-376' (Cucumis melo). As in previous assays, fruit from plants grafted onto 'Cobalt' yielded larger fruits, with wider seminal cavities. In fruit harvested from plants grafted onto 'Fian', 'Fimy' or onto the other Cucumis rootstock some mild differences that do not affect the market quality of fruit were found. All these results confirm the suitability of both hybrids as rootstocks for melon: they show good grafting performance, with reduced impact on fruit quality compared to Cucurbita rootstocks, and better resistance to the fungal pathogens that limit melon production worldwide.

El objetivo: La Influencia de las fases lunares en la fenología y producción en tres variedades de alfalfa (Medicago sativa). Método: Se consideró el experimental y con el diseño factorial, factores de estudios “A” las fases lunares y “B” variedades de alfalfa. Resultados: Se obtuvieron la cosecha después de establecimiento del promedio de 70 días, Tabla 1. La producción materia verde, por cortes y días, el siguiente: 35 y 44 días dependiendo de la estación del año. Tabla 2. Análisis de variancia de la materia verde en 190 días, existen el nivel de significancia entre las fases lunares y las variedades de alfalfa Fc=14.824, Fc=76.7698; F∞=3.05, F∞=3.44, y el coeficiente de la variabilidad de 11.33%. En la tabla 3. Se evalúa la media de rango múltiple de significancia de Tukey (0.01) en las fases lunares de la producción de materia verde del cultivo de alfalfa; se llegó a las siguientes conclusiones: primer lugar la Luna Cuarto Creciente con de 5,732.6401 Kg/há; segundo lugar la Luna Cuarto Menguante con 4,857.5098 kg/há; tercer lugar la Luna Nueva con 4,639.6499 kg/há; y por último la Luna Llena con una producción de 4,042.73 kg/há. Tabla 4 Efecto de las variedades (Factor de estudio “B”). En la prueba de significancia de Tukey en la variedad Cuf 101, fue superior de las demás con una producción de 6, 277.14 kg/há, segundo lugar está la variedad Moapa con 4,643.55 kg/há, y con menor producción de materia verde es la variedad W 350 con 3,533.68 kg/há.