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Introduction – The consumption of new exotic fruits, with their high nutritional and sensory value, has significantly increased in the past few years. Among the tropical fruits durian (Durio zibethinus Murr.) is less known than mango (Mangifera indica L.) and avocado (Persea americana). It has been shown that durian, mango and avocado possessed high nutritional and bioactive properties, but these data were determined using different methods. In order to obtain reliable results we investigated samples of durian, mango and avocado of the same stage of ripeness and unified methods were used for determination of the antioxidant potential. As far as we know, no results of such comparative investigation of three tropical fruits (durian, mango and avocado) and the use of such tests for phytochemical control have been published. Objective – Lyophilised durian, mango and avocado samples harvested in 2008 in Thailand and Israel were investigated. Methodology – The contents of crude protein, fat, carbohydrate, dietary fibre, total polyphenols, flavonoids, tannins and flavanols were determined by elemental analysis and UV spectroscopy. The presence of polyphenols (flavonoids and phenolic acids) in the investigated samples was studied by Fourier transform infrared (FT‐IR) spectroscopy and three‐dimensional fluorometry. Four complementary radical scavenging assays were used for antioxidant determination: ferric reducing antioxidant power (FRAP), 2, 2‐azino‐bis (3‐ethyl‐benzothiazoline‐6‐sulfonic acid) diamonium salt (ABTS•+), 1‐diphenyl‐2‐picrylhydrazyl method (DPPH) and cupric reducing antioxidant capacity (CUPRAC). Chemometrical processing was used for statistical comparison of the fruits. Results – All spectrometric measurements were highly correlated. The contents of total fibre, proteins and fats were significantly higher (p < 0.05) in avocado, and carbohydrates were significantly lower in avocado (p > 0.05) than in the two other fruits. The wavelength numbers of FTIR spectra for three investigated fruits were in the same range (1700–600 cm−1) as for catechin and gallic acid, used as standards. One main peak could be easily observed at the approximate location of ex/em 275/305 nm and the other one at ex/em 350/430 nm in the methanol polyphenol extracts of investigated fruits in three‐dimensional fluorescence, in contour and cross fluorescence maps. Similarity was found between durian, mango and avocado in polyphenols (9.88 ± 1.0, 12.06 ± 1.3 and 10.69 ± 1.1, mg gallic acid equivalents/g dry weight, d.w.), and in antioxidant assays such as CUPRAC (27.46 ± 2.7, 40.45 ± 4.1 and 36.29 ± 3.7, µM Trolox equivalent (TE)/g d.w.) and FRAP (23.22 ± 2.0, 34.62 ± 3.4 and 18.47 ± 1.9, µM TE/g d.w.), respectively. The multisample median test between all possible pairs of groups is a Tukey–HSD type comparison and denotes the different groups in a case when a pair‐wise test is significant and its q statistical value is greater than the table q parameter. The multisample median test of FRAP values were chosen from the compared fr...

The effect of nitrogen application levels (0.16 and 0.24 g N kg(-1) soil) on seed proteins and their amino acid compositions of amaranth (Amaranthus spp.) and quinoa (Chenopodium quinoa Willd) was studied. Total proteins of amaranth and quinoa had high contents of lysine (6.3-8.2 g 100 g(-1) protein) but low contents of methionine (1.2-1.8 g 100 g(-1) protein). Seed proteins were fractionated on the basis of different solubility in water, saline, and buffer as albumin-1 (Albu-1), albumin-2 (Albu-2), globulin (Glob), and glutelin (Glu) and were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Albu-1 was high in lysine (5.4-8.6 g 100 g(-1) protein), while Albu-2, which is a part of storage proteins, had a high leucine content (7.2-8.9 g 100 g(-1) protein) as an effect of different nitrogen application levels. Glu fractions were well-balanced in their essential amino acids with the exception of methionine. In conclusion, nitrogen application can be used for the nutritional improvement in human diet by increasing and maintaining protein and essential amino acid contents.

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The aim of this investigation was to determine the nutritional and bioactive properties of relatively less investigated exotic fruit durian (Durio zibethinus Murr.) and to compare these indices with widely used mango (Mangifera indica L.) and avocado (Persea americana). For this purpose HPLC, three-dimensional fluorescence (3D-FL), several radical scavenging assays and multivariate factor analysis were used. It was found a similarity in acetone extracts between durian and mango in the contents of polyphenols (1.66 ± 0.08, 1.48 ± 0.05, mg GAE g )1 DW, respectively), and in some antioxidant assays such as ABTS (11.98 ± 0.5, 12.24 ± 0.5, lm TE g )1 DW, respectively) and DPPH (5.61 ± 0.3, 5.22 ± 0.2, lm TE g )1 DW, respectively). Durian and avocado were similar in the contents of polyphenols, and ABTS and DPPH values in water and in methanol extracts, respectively. Based on the obtained results the nutritional and bioactive properties of durian are comparable with those indices in mango and avocado. In conclusion, durian can be recommended as a part of disease prevented diets.

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