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Effect of irradiation on the patulin content and chemical composition of apple juice concentrate.

The influence of ionizing radiation on the patulin content of apple juice concentrate was investigated. The results indicated that patulin, at an initial concentration of about 2 mg/kg, disappeared after irradiation of the concentrate with doses as low as 2.5 kGy. For lower doses, the extent of patulin degradation was proportional to the absorbed dose. Irradiation of the concentrate with doses sufficient for patulin disappearance did not change the titratable acidity, the content of reducing sugars and carbonyl compounds or the amino acid composition. The content of ascorbic acid slightly decreased and the colour of the concentrate brightened. The intensity of the patulin absorption spectra after irradiation of mycotoxin in aqueous solutions decreased.

Amino Acids↗

Electron paramagnetic resonance studies of gamma-irradiated corn.

Gamma-irradiated corn samples in the range 0.1-2.0 kGy dose range were studied by the EPR technique. The signal consists of one structureless line with a width of 0.82 +/- 0.02 mT and a g-factor of 2.004 +/- 0.002. The intensity of this line shows a linear dependence in this dose range. The corn samples were ground prior to irradiation. Before grinding the samples did not show any EPR signal. After grinding they present a free radical EPR line with the same characteristics as that produced by the gamma rays. The stability of these centers as a function of the temperature and time after irradiation was investigated. Analysis of these results suggest the presence of only one type of radical produced by both the mechanical and irradiation processes.

Electron Spin Resonance Spectroscopy↗

Electron spin resonance investigations of gamma-irradiated shrimp shell.

Gamma-irradiation of shrimp shell induces the formation of stable free radicals, which can be monitored by electron spin resonance (ESR) spectroscopy. The ESR spectrum of the free radicals is more complex than was originally reported, and was found to be species-dependent. The results presented include the effects of the following parameters on the ESR spectrum: different types of pre- and post-irradiation processing, absorbed dose, storage time, and species variations. The effects of these parameters on the ESR spectra are used to explain discrepancies between previously reported spectra for irradiated shrimp shell. Finally, the possible application of ESR spectroscopy as a tool for post-irradiation monitoring of shrimp is assessed.

Animals↗

A new approach for extension of the identification period of irradiated cellulose-containing foodstuffs by EPR spectroscopy.

We report on the possibility of identification by EPR spectroscopy of some irradiated cellulose-containing foodstuffs, at a relatively long time after the irradiation, when the characteristic EPR spectral lines of the cellulose free radical have essentially disappeared. In such cases rather expensive and time-consuming methods (e.g. thermoluminescence analysis) have to be applied. The present communication demonstrates with some pre-irradiated spices, dried medicinal and sweet herbs that simply heating the samples to 60 degrees C for one hour leads to a significant (50% or more) decrease of the EPR intensity of the remaining central line of the samples. For comparison, the loss in the intensity of the same line upon heating non-irradiated samples at 60 degrees C for one hour was only about 10%. This inexpensive new procedure will extend the post-irradiation period in which EPR can be used for distinguishing irradiated from non-irradiated samples, of certain cellulose-containing foodstuffs.

Cellulose↗

Identification of irradiation treatment of aromatic herbs, spices and fruits by electron paramagnetic resonance and thermoluminescence.

Electron paramagnetic resonance and thermoluminescence signals induced by gamma irradiation in some herbs, spices and fruits were systematically studied in order to detect the treatment. Using European protocols the validity and effectiveness of these two techniques are compared in regard to time of storage after irradiation.

Electron Spin Resonance Spectroscopy↗

[Effect of being fed gamma-irradiated fish on embryogenesis and the chromosomes of white rats].

Experiments on Wistar rats were made to study potential embryotoxic and cytogenetic effects of fresh and smoked fish subjected to gamma-irradiation. Embryotoxic action of irradiated fish was studied in 611 embryos obtained from 52 females. The number of alive and dead embryos, their mass, length and the presence of external and internal developmental abnormalities were determined. the animals' bone marrow cells were subjected to cytogenetic examination with the use of the metaphasic method. A total of 2426 cells from 35 rats were examined for the occurrence of chromosome aberrations. The examination has revealed no embryotoxic or cytogenetic action of both fresh and smoked fish subjected to gamma-irradiation.

Animals↗

[The use of ionizing radiation for the decontamination of salmonella-containing slaughtered broiler chickens and powdered eggs].

The effect of cobalt-60 gamma irradiation was investigated on the concentration of Salmonella (S.) typhimurium in artificial contaminated chicken carcasses and on the number of S. tennessee and S. agona in artificial contaminated spray-dried whole egg powder and liquid whole egg. Irradiation of carcasses and of liquid whole egg was carried out at deep frozen conditions between -10 degrees C and -18 degrees C and whole egg powder at 15-20 degrees C. The irradiation doses used where between 0.05 and 8.0 KGy. The D10-value of S. typhimurium in broiler chicks ranged between 0.57 and 0.74 and of S. agona respectively S. tennessee amounted to 0.95 and 1.07 in spray dried whole egg powder and 0.47 respectively 0.53 in whole egg content. Irradiation causes drastic reduction of physiological microflora in chicken carcasses. By radiation treatment using a dose of 4.0 KGy, germ count reductions by 3-5 decimal powers were achieved. Resistance of microbes increases in following succession: Pseudomonas spp., Salmonella spp., other Enterobacteriaceae spp., Micrococcus spp., Flavobacterium spp., yeasts, Bacillus spp., Streptomyces spp., fungi. Results of microbiological and sensorial examinations allow following conclusions: 1. Irradiation is highly effective against Salmonella. 2. Irradiation dose of 4.0 KGy is able to kill about 1 Million Salmonella bacteria per chicken. This guarantees safe elimination of natural occurring Salmonella bacteria in broiler chicken carcasses. 3. Irradiation of chicken carcasses up to 4.0 KGy causes no injury of quality, however storage longer than 4 months deteriorates sensorial qualities more than of unirradiated carcasses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Inhibition of microbial growth in chub-packed ground beef by refrigeration (2 degrees C) and medium-dose (2.2 to 2.4 kGy) irradiation.

Two studies were conducted to monitor microbial growth in chub-packed ground beef. In the first study, the effect of storage temperatures (2 and 7 degrees C) on chubs was examined for up to 18 days. Storage of chubs at 2 degrees C slowed microbial growth such that total counts exceeded 7.5 log10 cfu/g within 10 days compared to within 4 days for chubs stored at 7 degrees C. Microbial counts > or = 7.5 log10 cfu/g were associated with off-odors and samples were considered spoiled. The predominant microbes were homofermentative lactococci, although a gas-producing bacterium, Hafnia alvei, was prevalent in one of three trials. In the second study, medium dose (2.2 to 2.4 kGy) X-ray irradiation extended the shelf-life of chub-packed ground beef at 2 degrees C by approximately 14 days. Microbial counts on irradiated ground beef did not exceed 7.5 log10 cfu/g during 34 days of storage, while this level was reached in non-irradiated chubs by day 13. The predominant microbes on both non-irradiated and irradiated chubs were homofermentative lactococci; H. alvei was not isolated in the second study. These data indicated that refrigerated (2 degrees C) storage significantly delayed microbial spoilage in chub-packed ground beef, and that spoilage was further delayed when refrigerated (2 degrees C) ground beef chubs were exposed to medium dose irradiation.

Animals↗

Degradation of monoterpenes in orange juice by gamma radiation.

Single-strength orange juice was irradiated with 0, 0.89, 2.24, 4.23, and 8.71 gGy of gamma radiation at 5 degrees C and then stored at 7 degrees C for 21 days. Volatile compounds, isolated by solid-phase microextraction, were separated and identified using a gas chromatograph equipped with a mass selective detector. The majority of the volatile compounds were terpenes, and the most abundant volatile compounds were ethanol and limonene. Most volatile compounds were stable during the 21-day storage period except geranial and neral which decreased over time. Irradiation reduced the concentration of acyclic monoterpenes, such as geranial, neral, myrcene, and linalool 1 and 7 days after irradiation, but did not affect other monoterpenes, sesquiterpenes, or other volatile compounds. The reduction of acyclic monterpenes increased linearly with radiation dose, and correlated with an increase in thiobarbituric acid reactive substrates (TBARS) content. Reduction in the concentration of monoterpenes induced by irradiation was not significant 21 days after irradiation. Our results indicate that acyclic monoterpenes are sensitive to irradiation whereas most other volatile compounds are resistant.

Beverages↗

Analysis of gamma-irradiated melon, pumpkin, and sunflower seeds by electron paramagnetic resonance spectroscopy and gas chromatography-mass spectrometry.

Seeds of melon (Citrullus lanatus var. sp.), pumpkin (Cucurbita moschata), and sunflower (Heliantus annus) were gamma-irradiated at 1, 3, 5, and 10 kGy and analyzed by electron paramagnetic resonance (EPR) and gas chromatography-mass spectrometry (GC-MS) according to EN1787:2000 and EN1785:2003, respectively. Distinguishable triplet signals due to the presence of induced cellulose radicals were found at 2.0010-2.0047 g in the EPR spectra. The gamma-irradiated radiolytic markers of 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were identified in all irradiated seed samples. Both the free radicals and the alkylcyclobutanones were found to increase with irradiation dose. In general, linear relationships between the amount of radicals and irradiation dosage could be established. Studies at an ambient temperature (20-25 degrees C) in a humidity-controlled environment showed a complete disappearance of the cellulosic peaks for irradiated samples upon 60 days of storage. Such instability behavior was considered to render the usefulness of using EPR alone in the determination of irradiated seed samples. On the other hand, 2-DCB and 2-TCB were also found to decompose rapidly (>85% loss after 120 days of storage), but the radiolytic markers remained quantifiable after 120 days of postirradiation storage. These results suggest that GC-MS is a versatile and complimentary technique for the confirmation of irradiation treatment to seeds.

Cucurbita↗

Thiobarbituric acid reactive substances and volatile compounds in chicken breast meat infused with plant extracts and subjected to electron beam irradiation.

The effect of irradiation on thiobarbituric acid reactive substances (TBARS) and volatile compounds in raw and cooked nonirradiated and irradiated chicken breast meat infused with green tea and grape seed extracts was investigated. Chicken breast meat was vacuum infused with green tea extract (3,000 ppm), grape seed extract (3,000 ppm), or their combination (at a total of 6,000 ppm), irradiated with an electron beam, and stored at 5 degrees C for 12 d. The targeted irradiation dosage was 3.0 kGy and the average absorbed dosage was 3.12 kGy. Values of TBARS and volatile compound contents of raw and cooked chicken meat were determined during the 12-d storage period. Thiobarbituric acid reactive substances values ranged from 15.5 to 71.4 mg of malondialdehyde/kg for nonirradiated raw chicken and 17.3 to 80.1 mg of malondialdehyde/kg for irradiated raw chicken. Values for cooked chicken ranged from 31.4 to 386.2 and 38.4 to 504.1 mg of malondialdehyde/kg for nonirradiated and irradiated chicken, respectively. Irradiation increased TBARS and hexanal values of controls and meat infused with plant extracts. Hexanal had the highest intensity of volatiles followed by pentanal and other volatiles. Cooking the samples significantly (P < 0.05) increased the amounts of TBARS and volatiles. Addition of plant extracts decreased the amount of TBARS as well as hexanal and pentanal values. Although irradiation increases lipid oxidation, infusion of chicken meat with plant extracts could reduce lipid oxidation caused by irradiation.

Aldehydes↗