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81.
A simple method, using permanent modifiers, has been developed for chromium (Cr) determination in food of plant origin by the slurry sampling graphite furnace atomic absorption spectrometry. In particular comparison of the action of Mg(NO3)2, iridium (Ir)/niobium (Nb) and iridium (Ir)/tungsten (W) was examined. Finally, for chromium determination in food, the mixture of 2 μg of Ir with 10 μg of Nb was used as permanent modifier. The analytical procedure was optimised carefully on the basis of the data from pyrolysis and atomisation temperature curves studies. The results obtained for four certified reference materials using external calibration with aqueous standards were in good agreement with the certified values. The precision and accuracy of Cr determination by the described method were also acceptable: the RSD were lower than 10% and recoveries for CRMs were in the range of 95-103%. The characteristic mass for chromium was determined to be 3.9 pg and the detection limit for the optimised procedure at the 0.75% (w/v) slurry concentration - 86.6 ng g−1. 相似文献
82.
Udaya N. Wanasundara Ryszard Amarowicz Fereidoon Shahidi 《Food research international (Ottawa, Ont.)》1995,28(6):525-530
Defatted canola meal was extracted with 95% (v/v) ethanol at 80 °C. The extract was fractionated on a Sephadex LH-20 column using methanol as eluate. Seven major fractions were isolated according to UV absorption, content of phenolics and sugars. Antioxidant activity of these fractions was evaluated in a β-carotenelinoleate model system. Fraction IV showed the best antioxidant effect by exhibiting the highest preventive activity against the bleaching of β-carotene. Further separation of this fraction on TLC indicated that it contains several compounds including phenolic acids and trihydroxy phenolic compounds such as flavones and flavonols. 相似文献
83.
Shuxun Shao Xiubo Mi Laurent Ouerdane Ryszard Lobinski Juan Francisco García-Reyes Antonio Molina-Díaz Andrea Vass Mihály Dernovics 《Food Analytical Methods》2014,7(5):1147-1157
Orthogonal liquid chromatographic (ion exchange, reversed phase, and ion pairing) and mass spectrometric [electrospray ionization (ESI)-TOF-MS, ESI-Orbitrap MS, and inductively coupled plasma mass spectrometry (ICP-MS)] methods were addressed to identify and quantify selenium species from a naturally Se-enriched green bean (Phaseolus vulgaris vulgaris) sample after proteolytic digestion. While selenomethionine (10.1 mg/kg as Se) and selenate (9.5 mg/kg as Se) could be quantified in a straightforward way by anion exchange LC-ICP-MS technique, a multistep purification protocol was required to identify Se-methylselenocysteine and γ-glutamyl-Se-methylselenocysteine in an unambiguous way prior to quantification by using either in-source fragmentation (LC-ESI-TOF-MS) or collision-induced dissociation (LC-ESI-Orbitrap MS). Finally, Se-methylselenocysteine (2.6 mg/kg as Se) and γ-glutamyl-Se-methylselenocysteine (1.2 mg/kg as Se) could contribute to the overall selenium recovery of 72 %. This sample is the first of the Faboideae subfamily and Phaseolus ssp. to be speciated to such an extent for selenium including γ-glutamyl-Se-methylselenocysteine, a highly potential selenium species, which makes this bean material an ideal candidate for functional food purposes. 相似文献
84.
Juana Frias Concepcion Vidal-Valverde Halina Kozlowska Ryszard Gorecki Johana Honke Clifford L. Hedley 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1996,203(1):27-32
Seeds of pea (Pisum sativum L. cv. Ergo), faba bean (Vicia faba ssp. minor Harz., cv. Tibo) and yellow pea lupin (Lupinus luteus L. cv. Juno) were sampled at different days after flowering (DAF) and their content of soluble carbohydrates was determined: Analysis of samples showed thatmyo-inositol, fructose, glucose, galactose and sucrose were found in high abundance early in development and their content decreased gradually during maturation. -Galactosides, which includes the content of raffinose, stachyose and verbascose, started to appear later in seed development, at 37 DAF in peas, 40 DAF in faba beans and 45 DAF in lupins. Their accumulation increased considerably during seed growth, and the maximum content was obtained in mature seeds; 3.8% in peas, 4.5% in faba beans and 10.4% in lupins. Results obtained for these sugars during seed development were fitted to modelling curves in order to predict sugar content at different development stages. 相似文献
85.
Bogdan Smyk Piotr Wieczorek Ryszard Zadernowski 《European Journal of Lipid Science and Technology》2011,113(5):592-596
There is no simple method available to estimate the concentration of conjugated fatty acids (CFA) with more than two double bonds in plant oils, because there are no commercially available complete sets of CFAs standards needed for such analysis. This paper presents such a method based on the absorption and fluorescence spectra of available CFAs standards and a computer program calculation. Using this method, the concentrations of the α‐eleostearic acid (conjugated trienoic acid (ELA) 8.8 × 10?4 mol/L) and cis‐parinaric acid (conjugated tetraenoic acid (PnA) 3.5 × 10?5 mol/L) in evening primrose oil were estimated. The accuracy of the calculation method is around 10%. Practical applications: This is the first report about the existence of CFAs in evening primrose oil. The described method estimates the total concentration of trienes, tetraenes, and pentaenes in evening primrose oils without using HPLC or other analytical methods. These CFAs are important from a health point of view. They are not synthesized by the human body. Therefore, plant oils containing these fatty acids (FA) are very valuable. Knowledge about the concentrations can be utilized to prepare a mixture of the plant oils with a favourable n‐3 to n‐6 FAs ratio and in addition containing CFAs. 相似文献
86.
Katarzyna Majewska Joanna K. Banach Ryszard Żywica Ireneusz Białobrzewski 《International Journal of Food Properties》2013,16(2):392-406
The work aimed at determination of electric properties of wheat grain in dependence on its variety, moisture, geometrical features of kernels and applied current frequency. Wheat grain of 4 Polish winter varieties: Korweta, Juma, Mikon and Kobra from harvest 2001 were used as the material for study. Grain was sized into 3 fractions: (1) > 2,8mm, (2) 2,5–2,8mm, and (3) 2,2–2,5mm. Basic geometrical features were determined for not sorted grain (control sample) and its three fractions by the use of digital image analysis. Electric properties of grain (at 11% and 15% moisture content) have been performed with the Hewlett Packard 4263B meter. Measurements of impedance, resistance, admittance, conductance, as well as equivalent parallel capacitance and equivalent series capacitance were made. Obtained results were subjected to statistical analysis with the use of Statistica? programme. Changes in electric properties of grain significantly depended on all of studied factors. Most of all significant correlations appeared between geometrical features and studied electric properties of grain of 15% moisture. Statistical analysis of the results proved significant linear correlations between electric properties of kernels and their length, perimeter and circularity coefficient RC2 at higher measurement frequencies. 相似文献
87.
Artur Dybko Wojciech Wroblewski Janusz Maciejewski Zbigniew Brzozka Ryszard S. Romaniuk Jedrzej Kielkiewicz 《应用聚合物科学杂志》1996,59(4):719-723
The article presents a new idea of the application of polymer track membranes (PTM) for immobilization of a reagent in fiber optic chemical sensors. PTM was made of a poly(ethylene terephthalate) foil (10 μm in thickness, pores of 0.2 μm in diameter). The usefulness of membranes additionally covered by poly(vinyl chloride) was tested in a fiber optic redox titrator. The titrator utilized N,N′-diphenylbenzidine as a reagent which changes its absorbance in dependence on the redox potential. The measuring system is based on a lightemitting diode and a silicon photodiode connected to a bifurcated fiber optic bundle. The gain is in price and availability of the membrane. © 1996 John Wiley & Sons, Inc. 相似文献
88.
Dense films of poly[(4-ethylphenoxy)(phenoxy)phosphazene] (PEPP), a potentially attractive ion-exchange membrane material, were crosslinked to varying degrees using UV light and a photoinitiator. This polymer contained two kinds of substituents: phenoxy groups to be used for possible functionalization (e.g., sulfonation) and ethylphenoxy side-chains for photocrosslinking, where hydrogens at the benzylic carbons could be abstracted by a photoinitiator-leaving macroradicals that after recombination formed covalent bonds. The polyphosphazene polymer was synthesized, mixed with a photoinitiator, shaped into a thin film by solvent casting, and irradiated with UV light for a specified period of time. Benzophenone (BP), was selected as the photoinitiator because it was miscible with poly-phosphazene, had the highest rate of hydrogen abstraction, and absorbed UV light of 365 nm wavelength. The half-life of benzophenone in 50 μm-thick irradiated films was determined to be 20 min. When the BP–PEPP molar ratio was increased from 0 to 0.5, the glass transition temperature increased after irradiation from −8.8 to 53.5°C. At the same time, the equilibrium swelling in dimethylacetamide, at 25°C, decreased from infinity to 0.31. Tensile strength tests of the crosslinked films revealed a nonlinear dependence on BP–PEPP molar ratio. © 1996 John Wiley & Sons, Inc. 相似文献
89.
It was shown using several examples that the ratio of apparent viscosity and Newtonian viscosity at the same temperature as function of shear stress is independent of temperature. It means that viscosity curves for different homogeneous polymer systems measured in various temperatures create a common master curve, which is very convenient for practical calculations of many technically important flows. It was also shown that for such systems, the stress dependence can be often very well described by simple function of Kohlrausch type. Moreover, it was found that for small-amplitude oscillatory shear, similar master curves can be created by representing the absolute value of complex viscosity or its components as functions of absolute value of complex modulus. For nonhomogeneous systems, second-order temperature effects may appear. They were taken into account by additional rule based on the so-called no-flow temperature. It was also shown that the first normal stress difference as function of shear stress is temperature independent. POLYM. ENG. SCI., 60:44–54, 2020. © 2019 Society of Plastics Engineers 相似文献
90.
Pawe Kowalczyk Mateusz Szymczak Magdalena Maciejewska ukasz Laskowski Magdalena Laskowska Ryszard Ostaszewski Grzegorz Skiba Ida Franiak-Pietryga 《International journal of molecular sciences》2021,22(2)
Silver and its nanoparticles (AgNPs) have different faces, providing different applications. In recent years, the number of positive nanosilver applications has increased substantially. It has been proven that AgNPs inhibit the growth and survival of bacteria, including human and animal pathogens, as well as fungi, protozoa and arthropods. Silver nanoparticles are known from their antiviral and anti-cancer properties; however, they are also very popular in medical and pharmaceutical nanoengineering as carriers for precise delivery of therapeutic compounds, in the diagnostics of different diseases and in optics and chemistry, where they act as sensors, conductors and substrates for various syntheses. The activity of AgNPs has not been fully discovered; therefore, we need interdisciplinary research to fulfil this knowledge. New forms of products with silver will certainly find application in the future treatment of many complicated and difficult to treat diseases. There is still a lack of appropriate and precise legal condition regarding the circulation of nanomaterials and the rules governing their safety use. The relatively low toxicity, relative biocompatibility and selectivity of nanoparticle interaction combined with the unusual biological properties allow their use in animal production as well as in bioengineering and medicine. Despite a quite big knowledge on this topic, there is still a need to organize the data on AgNPs in relation to specific microorganisms such as bacteria, viruses or fungi. We decided to put this knowledge together and try to show positive and negative effects on prokaryotic and eukaryotic cells. 相似文献