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EN
In the present work the carbon and nitrogen isotopic composition of food products bought in the retail trade in Warsaw is demonstrated. The research was carried out using meat (pork, chicken), hen eggs and honey. These products originated from the conventional and ecological farms. The values of the isotopic ratios are expressed as δ notation and correspond to the international standards (V-PDB for δ13C, and air for δ15N) according to the following general formula: δ(‰) = [(R sample / R standard) – 1] × 1000, where R represents the ratio between the less abundant and more abundant isotopes, in particular 13C/12C and 15N/14N. The results received in our laboratory, were compared with results presented in the literature for similar products. The results of the study show that the N and C stable isotope ratios in the tested products can be applied to verify their authenticity.
EN
Results of the examination of the variety of dry plant extracts (Thyme extract, Celery seed extract, Artichoke extract, Citrus aurantium extract and others) by two different detection methods are described. Both PSL and TL methods are presented and discussed. Comparative study based on the analysis of the results obtained by thermoluminescence (TL) and photostimulated luminescence (PSL) measurements delivered the arguments that preselection of detection methods based on model studies is rational to be adapted in analytical laboratories specialized in the detection of irradiated foods.
EN
The results of experiments on the detection of irradiated component in commercial flavour blends composed of a mixture of non-irradiated spices, herbs and seasonings are presented. A method based on the thermoluminescence measurements on silicate minerals isolated from blends has been adapted. It has been proved that by applying this technique it is possible to detect 0.05% by weight of paprika, irradiated earlier with a dose of 7 kGy, which was a minor component of nonirradiated flavour blends.
EN
The results of our own detection of irradiation in various foods: meat, poultry, fishes, spices, dried fruits, mushrooms, crops, fresh fruits and food additives are presented. The techniques for detection whether foods have been irradiated or not, such as EPR spectrometry, thermoluminescence (TL), DNA damage by "comet" method and ability for germination of grains has been discussed. The applicability of particular technique to specific food-stuffs has been indicated.
PL
Przedstawiono własne wyniki detekcji napromieniowania różnych rodzajów żywności: mięsa, drobiu, ryb, suszonych owoców, orzechów, grzybów, zbóż, świeżych owoców oraz dodatków do żywności. Omówiono zastosowanie do oceny czy żywność była napromieniowana, czy nie, techniki EPR, termoluminescencji (TL), metody "kometkowej" badania uszkodzeń DNA, oraz pomiarów zdolności kiełkowania. Wskazano zakres stosowalności poszczególnych technik w stosunku do różnych rodzajów żywności.
6
Content available remote Application of the DNA comet assay for detection of irradiated meat
EN
Radiation induces damage to the DNA. This damage (fragmentation) can be assessed in the irradiated food using Single Cell Gel Electrophoresis (SCGE), known as DNA comet assay. Fragmentation of DNA may also be caused by improper storage of meat and repeated freezing and thawing. This makes identification of irradiated meat by this assay not reliable enough. In order to know the scale of the processes imitating irradiation effects in DNA of the comets, their shape and lenghts were examined in both unirradiated and irradiated fresh meat (D = 1.5 or 3.0 kGy) stored at 4°C or frozen (-21°) up to 5 months. Comets formed upon SCGE were stained with DAPI or silver and examined in fluorescent or light microscope. They were divided arbitrarily into 4 classes. Comets of class IV were found quite often in fresh meat stored at 4°C. In meat samples that were irradiated and stored frozen, comets of class, I, II and III were observed. The negative comet test is univocal. Positive comet test, however, needs confirmation. The meat should be subjected to further analysis with other validated methods.
PL
Promieniowanie powoduje uszkodzenia DNA. Te uszkodzenia (fragmentację) można ocenić w napromieniowanej żywności stosując elektroforezę w żelu pojedynczej komórki, zwaną także testem kometowym. Fragmentację DNA w mięsie mogą także wywoływać: nieprawidłowe przechowywanie mięsa oraz powtarzane zamrażanie i rozmnażanie. Czyni to identyfikację napromieniowania mięsa mniej wiarygodną. W celu poznania procesów imitujących napromieniowanie, tj. powodujących powstawanie kometek DNA, oceniano ich kształt i długość w mięsie nie napromieniowanym i napromieniowanym dawką 1.5 lub 3.0 kGy przechowywanym w 40C lub w stanie zamrożenia do 5 miesięcy. Otrzymane kometki DNA barwiono barwnikiem fluorescencyjnym DAPI lub srebrem i badano w mikroskopie fluorescencyjnym lub zwykłym. Kometki podzielono na 4 klasy. Kometki IV klasy znajdowano często w mięsie przechowywanym w 40C. W próbkach mięsa napromieniowanego i przechowywanego w stanie zamrożenia obserwowano kometki klasy l, II i III. Negatywny test kometowy jest jednoznaczny. Test dodatni wymaga potwierdzenia przez zastosowanie innych metod dających miarodajne wyniki.
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