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- Author or Editor: M. Jakšić x
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Abstract
The use of X-ray tube fluorescence spectrometer with composite secondary target radiator is explained. Experimentally measured efficiencies and detection limits for coal samples are presented and discussed.
Abstract
A ring-shaped, 109 Bq241Am radioisotope source was used for the excitation of K-shell X-rays from rare earth elements (56<Z<64), present in powdered geological material. In order to improve the efficiency of the measurement of these elements in the concentration range down to 10 ppm, the optimum geometry of the system was found. The results obtained are presented and discussed.
Maize samples collected in Serbia during a period of seven years were investigated on the presence of fumonisins. Concentration of fumonisins was determined by validated direct competitive Enzyme Linked Immunosorbent Assay method. This method was in accordance with European Union requirements, therefore accredited and performed in the Serbian accredited official laboratory. Summary analysis of all obtained results revealed fumonisins contamination in 82% of the total of 291 maize samples with average contamination being 1.515 mg/kg. An increase in the percentage of contaminated samples (from 51 to 100%), as well as an increase in mean fumonisin concentration in positive samples (from 0.227 to 3.281 mg/kg) and median values in positive samples (from 0.070 to 2.140 mg/kg) was noticed during the observation period. Although in Serbia there is no regular control of fumonisins in corn for animal feeding, long-term results indicate their wide distribution in this grain. Since the data on climate elements show change in temperature and precipitation in relation to multiannual average on the territory of Serbia, further research on the effects of climate change on the development of mold, the appearance of insects and the production of toxins are necessary in order to check the resistance of currently grown hybrids in the territory of Serbia on fungal growth and fumonisins production.
Abstract
Rye is an important raw material of bread due to tradition and its favourable nutritional and technological qualities. Despite the beneficial fibre composition, a special group of short-chain carbohydrates, the so called FODMAPs (fermentable oligo-, di-, monosaccharides and polyols) may cause problems for patients with irritable bowel syndrome. The aim of our work was to investigate the non-starch carbohydrate (dietary fibre compounds, short-chain carbohydrates) composition of rye varieties, and of their novel milling fractions obtained from industrial milling trials and test loaves made from them. Regarding fibre and short chain carbohydrate composition, rye varieties did not show significant differences. In new subfractions, fibre and FODMAP composition were described, among profiles most of them differ from commonly used flours, independently from variety. The yeast fermentation and baking caused a decrease in water-extractable arabinoxylan content, at the same time increased the substitution pattern of water-extractable arabinoxylans. Furthermore, breadmaking process decreased the fructan content, and therefore increased the fructose level, thus modifying the short-chain carbohydrate composition. Based on our knowledge, this research is among the first ones investigating the fibre and short-chain composition of rye from the seeds to the consumable final products.
