A spectrofluorimetric method and a chromatographic method [high-performance liquid chromatography -ultraviolet (HPLC-UV) detection] were compared for vitamin C analysis of green beans. For HPLC-UV, the determination was performed before [ascorbic acid (AA)] and after reduction with dithiothreitol [AA c dehydroascorbic acid (DHAA)]; for spectrofluorimetry, DHAA was determined after oxidation with activated charcoal. The fluorimetric determination of DHAA before oxidation was also carried out, and showed good precision but poor accuracy (very high recovery percentages). HPLC-UV showed better linearity and sensitivity, while spectrofluorimetry was more precise. Both methods were suitable for green bean samples, and the choice of which one to use depends on the particular interest of the analysis: spectrofluorimetry may be preferable when the total content of vitamin C is required, but not for individual analysis of each form. HPLC-UV is more suitable when the interest of the analysis is the ascorbic acid form as a deterioration index of vegetable products.

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A high-performance liquid chromatography (HPLC) method for soluble sugars analysis, using an [[(aminopropyl)methyl]silyl]-bonded amorphous silica column, was applied to several dry legumes:  chickpeas, lentils, white beans, pinto beans, and peas. Monosaccharide (ribose, fructose, glucose, and galactose), disaccharide (sucrose, maltose, and melibiose), and oligosaccharide (raffinose, ciceritol, and stachyose) composition of these samples was analyzed, with special interest on α-galactosides, because of their physiological role in inducing flatulent phenomena in humans after ingestion of legumes. Ciceritol (an inositol digalactoside) was the main sugar in chickpea samples and it was present also in lentils. In all the samples stachyose was found at higher levels than raffinose, and the content of these two flatulence-inducing sugars is higher in beans and lentils and lower in peas and chickpeas. However, great variability has been found in the sugar content of the different samples analyzed, probably due to genetic and environmental factors. The proposed method showed good results for the analysis of 10 simple and complex sugars in legumes, in a final time of about 40 min and in the same chromatographic run. Keywords: Soluble sugars; oligosaccharides; α-galactosides; legumes; HPLC

: Analyses of the nutritional composition of tender leaves of three species of Sonchus (S. asper L, S oleraceus L and S tenerrimus L) from di †erent locations in the south east of Spain were carried out. The proximate composition, as well as the content of mineral elements (Na, K, Ca, Mg, P, Fe, Cu, Zn and Mn), fatty acids, vitamin C, carotenoids and oxalic acid were determined. The results, which referred to fresh weight, emphasised the low proportion of available carbohydrates. Vitamin C contents were high, and ranged from 457 mg kg~1 (S tenerrimus) to 779 mg kg~1 (S oleraceus). Carotenoids were found in a high proportion (158 mg kg~1) in S oleraceus. Mineral element contents were similar to other green leafy vegetables. Fibre was present in amount above 30 g kg~1 in the three species. Essential fatty acids of the u3 series were highest in S oleraceus (44É97%). It is believed that these species of Sonchus could be used for nutritional purposes, due to the high concentrations of nutrients that they contain.1998 SCI. ( Sci Food Agric 76, 628È632 (1998) J

The composition of tender leaves from five species of the family Cruciferae (Alliaria petiolata, Cardaria draba, Cakile maritima, Capsella bursa‐pastoris and Sisymbrium irio)from different locations of the southeast of Spain (Almeria) was investigated. The proximate composition, mineral elements (Na, K, Ca, Mg, P, Fe, Cu, Zn and Mn), fatty acids, vitamin C, carotenoids and oxalic acid contents were determined. The available carbohydrate contents ranged from 1.4% ‐ 8.2%. Vitamin C contents were high, specially in Alliaria petiolata (261 mg/100 g). Carotenoid content was relatively high in Alliaria petiolata (13.3 mg). Mineral elements were present at higher concentrations than is common for other green leafy vegetables. Fiber amounts were also remarkable (1.96–5.38 g/100 g). The ω3 series of fatty acids were predominant in the three species (Capsella bursa‐pastoris 54.02%). Oxalic acid values and ratios of oxalic acid/Ca were moderate, being higher in C. maritima. We believe that these species of crucifers could be used for dietary purposes, due to the amount and diversity of nutrients they contain.