Identification Of Irradiated Food Research Articles

European inter-comparison studies as a tool for perfecting irradiated food detection methods

Abstract In this paper, we present the results of inter-comparison studies on identification of irradiated food carried out by the leading European laboratories from 1991 to 2018. In 1990s, the Federal Institute for Health Protection of Consumers and Veterinary Medicine in Germany played the leading role in the organization of the inter-laboratory tests on this subject. At the beginning of the present century, the Spanish Agency for Food Safety and Nutrition and Food National Spanish Centre took over this role. In total, 47 international tests were carried out in which nearly 500 samples of alimentary products were analysed in 37 laboratories from 14 European countries. The tests were aimed at proving the reliability of analytical methods – thermoluminescence (TL), photostimulated luminescence (PSL), and electron paramagnetic resonance (EPR) spectroscopy – for identification of specific irradiated food products and to control the analytical skills and experience of participating laboratories. The results made possible a discussion on why some irradiated food samples are more difficult for identification. In general, the tests showed that TL measurements of products such as herbs, nuts, peppers, and raisins, and EPR studies of fish and chicken bones, fresh strawberries, and dried fruits could be used as reliable control methods. The challenge that control laboratories are facing now, is related to the identification of complex food products such as diet supplements or biopharmaceuticals, in which only some additives are irradiated.

Potential of thermoluminescence analysis over electron paramagnetic resonance approach to identify irradiated shrimp even after cooking

Thermoluminescence (TL) technique and Electron Paramagnetic Resonance (EPR) spectroscopy were employed to identify irradiated Indian shrimp after prolonged storage of 65 days and cooking at maximum temperature of 120°C. The composition of isolated minerals from intestinal grits revealed the origin of thermoluminescence. The TL glows of irradiated samples were characterized by a peak at around 220°C. Radiation-induced TL signal was detected even after cooking at 120°C. In case of EPR spectroscopy outer shell of the shrimp was chosen to study paramagnetic species. An anisotropic radiation induced paramagnetic center was found and characterized by g⊥ = 2.0046 and g|| = 1.997 for the shrimps exposed to 8 kGy. However, radiation-specific EPR signal disappeared after cooking and was not able to help detect irradiation below 3–4 kGy. The results of this study suggested potential of TL technique in identification of irradiated and cooked shrimp exposed to commercially relevant radiation doses. Practical applications Radiation processing is one of the important food preservation technologies. Preservation by ionizing radiation can play an important role in hygienization of shrimps, thereby, contributing toward export of sea-foods. Identification of irradiated food is of paramount importance to consumer, facility operators, and regulators. However, detection of negligible changes in irradiated food matrix is a challenging task. The present study explains the potential of two independent approaches based on thermoluminescence (TL) and electron paramagnetic resonance (EPR) spectroscopy in detection of irradiated shrimp. Further, TL technique exhibited potential to identify irradiated shrimp even after cooking. The results obtained could be of immense help toward all the stakeholders associated with this technology in consumer acceptance, and decision making.

An improved approach to identify irradiated spices using electronic nose, FTIR, and EPR spectroscopy.

Changes in cumin and chili powder from India resulting from electron-beam irradiation were investigated using 3 analytical methods: electronic nose (E-nose), Fourier transform infrared (FTIR) spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The spices had been exposed to 6 to 14 kGy doses recommended for microbial decontamination. E-nose measured a clear difference in flavor patterns of the irradiated spices in comparison with the nonirradiated samples. Principal component analysis further showed a dose-dependent variation. FTIR spectra of the samples showed strong absorption bands at 3425, 3007 to 2854, and 1746 cm(-1). However, both nonirradiated and irradiated spice samples had comparable patterns without any noteworthy changes in functional groups. EPR spectroscopy of the irradiated samples showed a radiation-specific triplet signal at g = 2.006 with a hyper-fine coupling constant of 3 mT confirming the results obtained with the E-nose technique. Thus, E-nose was found to be a potential tool to identify irradiated spices.

Liquid Chromatography–Electrospray Ionization Tandem Mass Spectrometric Analysis of 2-Alkylcyclobutanones in Irradiated Chicken by Precolumn Derivatization with Hydroxylamine

Food irradiation is a common preservation method that is used in many countries. The ability to identify irradiated food is important for assuring compliance with regulatory policies, such as food labeling requirements, and for informed consumer choice. There is thus a significant demand for analytical methods of high sensitivity and selectivity to identify irradiated food, especially for foods subjected to low-dose irradiation and for processed or composite foods that contain small quantities of irradiated ingredients. 2-Alkylcyclobutanones (2-ACBs) are uniquely formed during food irradiation and have been adopted by the European Committee for Standardization as signature biomarkers for the identification of irradiated foods. We now report the development of a novel assay for quantification of 2-ACBs in γ-irradiated food by liquid extraction of fat content followed by precolumn derivatization and liquid chromatography-tandem mass spectrometric (LC-MS/MS) detection. Precolumn derivatization with hydroxylamine introduced a polar functional group into the otherwise nonpolar 2-ACBs, which greatly enhanced ESI-MS response. The method was validated for extraction efficiency, precision, accuracy, and detection limit. In comparison with the current GC-MS based European official method (EN1785:2003) for 2-ACBs determination, our new LC-MS/MS method offers a more efficient sample processing protocol with reduced solvent consumption. More importantly, the combination of chemical derivatization and LC-MS/MS detection significantly enhanced the analytical sensitivity of the method, which allows confident identification of food irradiated with as little as 10 Gy. To the best of our knowledge, this is the first report of 2-ACB determination by LC-MS/MS and the first analytical method allowing confident identification of irradiated food at dosage of down to 10 Gy.

Electron Spin Resonance Spectroscopy for the Identification of Irradiated Foods with Complex ESR Signals

Electron spin resonance (ESR) spectroscopy for the detection of irradiated food could provide complex spectra due to the presence of different nonirradiation-specific paramagnetic species in the sample. Particularly, ESR signals from naturally present Mn2+ could limit the ESR-based detection of irradiated foods of plant origin. In this study, the effects of different concentrations of Mn2+ on the radiation-specific ESR spectral features of radiation-induced crystalline sugar or cellulose radicals were examined. Soy sauce powder with Mn2+ was irradiated at 10 kGy and its effect on the identification of radiation-induced sugar (pak choi, 10 kGy) and cellulose (red pepper powder, 10 kGy) radicals was evaluated. In the blends of red pepper and soy sauce, the left (g 1 = 2.025) and central (g 2 = 2.005) peaks of the cellulose signal significantly decreased with the decline of red pepper content (R 2 = 0.9384, g 1; 0.8819, g 2). However, the right peak (g 3 = 1.988) significantly increased (R 2 = 0.9353, g 3) with an escalation in the soy sauce content. The cellulose radical signals were identifiable from the blends containing more than 50 % red pepper powder. In the blends of soy sauce and pak choi, the ESR intensity of crystalline sugar radicals significantly decreased with the decline in pak choi content (R 2 = 0.9887). However, Mn2+ signal didn’t overlap with the sugar radical signals. The ESR signals from radiation-induced crystalline sugar remained unaffected; however, the signals from cellulose radicals provided a reduced detectionability depending upon the concentration of Mn2+ in the sample.

Identification and dosimetry of irradiated walnuts (Juglans regia) using EPR

Electron paramagnetic resonance (EPR) is an easy, fast, and reliable tool for identification of irradiated food. Untreated nuts may encounter hazards of carrying several pathogens or microbial contamination; walnuts are of specific importance due to their nutritional and medicinal values, and hence walnut processing via gamma irradiation is a necessary step. EPR was employed for the identification and dosimetry of Cs-137 gamma-irradiated walnuts (shells and kernels). Several important parameters were studied, such as spectral features, microwave power dependence of signal intensities, and short- and long-term time dependences. Responses of walnut shells and kernels to different radiation doses in the range 0–10 kGy were investigated. Results confirmed that EPR is a suitable tool for the identification and dosimetry of irradiated walnuts using either their shells or only kernels.

A preliminary approach to identify irradiated foods by thermoluminescence measurements

Thermoluminescence (TL) is one of the physical methods for the identification of irradiated foods. Among the currently developed methods, TL is the most widely used method for the identification of irradiated foods. However, in order to use this method, silicate minerals should be isolated from food samples. The process for the isolation of silicate minerals is time consuming and laborious. In this work, we have investigated the applicability of the TL method using iron-containing minerals instead of silicate minerals. In the TL analyses of dried spices, TL glow curves of iron-containing minerals showed maximum temperatures between 150 and 250°C which were the same as those of silicate minerals. The process for the mineral separation of the proposed method is simple, fast, easy, and reliable. Moreover, the analysis results including TL ratio have not shown significant differences compared with the silicate minerals method. As a result, the TL measurements using the iron-containing minerals could be an excellent method for the identification of the irradiated foods, including dried spices.

Identification of low amount of irradiated spices (red pepper, garlic, ginger powder) with luminescence analysis

For the identification of irradiated food, current analysis methods have limitations regarding presence and stability of radiation-induced markers. In this study, different spice blends with small quantity of different irradiated (0, 1 and 10kGy) spice powders, such as red pepper, garlic or ginger, were investigated using PSL and TL techniques. In PSL-based screening analysis, the spice blends containing 10% of irradiated materials (1 or 10kGy) were determined as intermediate or positive. In TL results, the blends containing 1% of 1 or 10kGy-irradiated spices showed the typical TL glow curves that could be interpreted as positive. The blends with irradiated garlic powder provided more good results where identification was possible at 0.5% mixing of irradiated sample. However, the TL ratios of all spice blends were <0.1 and only TL glow curve shape and intensity may be used to discriminate the samples having irradiated component.

Comparison of elemental contents of Korean space foods using instrumental neutron activation analysis

The analysis of mineral contents in space foods is needed to obtain an information on a comprehensive elemental composition as well as the investigation on the effects of human nutrition and health based on the dietary intake of mineral elements. Recently, six items of new Korean space foods (KSFs) such as kimchi, bibimbap, bulgogi, a ramen, a mulberry beverage and a fruit punch which was developed by the KAERI, and the contents of more than 15 elements in the samples were examined by using instrumental neutron activation analysis (INAA). Five biological certified reference materials, NIST SRM were used for analytical quality control. The results were compared with those of common Korean foods reported, and these results will be applied toward the identification of irradiated foods.

Silicates collected from personal objects as a potential fortuitous dosimeter in radiological emergency

Abstract The use of silicates as thermoluminescent material is well known and ranges from the identification of irradiated food to the dose reconstruction using quartz extracted from bricks and tiles. Recently the possibility to collect silicates from the dust present on personal objects for individual dosimetry in case of radiation accident or radiological attack, was investigated for dose of 10 Gy. The aim of the present work was to investigate the possibility to detect dose levels below 10 Gy. To this extent objects supposed to contain high amount of silicates such as keys, coins and cigarette tobacco ( Bortolin et al., 2010 ) were tested in the dose range 0.1–5.0 Gy. The TL signal was distinguishable from the geological signal in the whole range of dose. To simulate a realistic situation, laboratory irradiation was performed directly on the objects before silicates collection and TL analysis were carried out at two different time points, within a week. The glow curves registered 7 days after laboratory irradiation at 5 Gy showed an artificially radiation-induced TL signal well distinguishable from the natural background.

Evaluation of the original dose in irradiated dried fruit by EPR spectroscopy

Abstract The electron paramagnetic resonance spectroscopy (EPR) is one of the physical methods, recommended by the European Committee for Standardization, for the identification of irradiated food containing cellulose, such as dried fruit. In this work the applicability of EPR as identification method of irradiated pistachios, hazelnuts, peanuts, chestnuts, pumpkin seeds is evaluated; the time stability of the radiation induced signal is studied and the single aliquot additive dose method is used to evaluate the dose in the product.

The identification of irradiated crustaceans and evaluation of the dose by thermoluminescence: Intercomparison between two methods for extracting minerals

Abstract The thermoluminescence (TL) is one of the physical methods recommended by the European Committee for Standardization, for the identification of irradiated food from which silicate minerals can be extracted. The efficacy of the method strongly depends on the quantity and purity of the extracted minerals, and therefore on the extraction procedure. In this work we applied the TL for the identification of crustacean Nephrops norvegicus irradiated at 0.5−1.5−3.0 kGy, comparing two different procedures for extracting minerals: by means of a density gradient or with acid hydrolysis. The identification of the irradiation treatment was always achieved with both procedures, without any false positive. A dose reconstruction method was also set up and tested. A little preference should be given to the acid hydrolysis extraction procedure, that requires less quantity of food sample and reagents, as well as less time to be carried out, and gives a satisfactory reconstruction of dose.

Would it Still be Possible to Identify Irradiated Lipid-containing Foods Towards the End of their Shelf-life?

The current British and European Standard (BS EN1785: 2003) for the identification of gamma irradiated foods is based on the isolation and detection of a group of lipid derived 2-alkylcyclobutanone compounds that are formed following irradiation. The 2-alkylcyclobutanones (2-dodecylcyclobutanone {DCB}, and 2-tetradecylcyclobutanone {TCB}) have been validated as radiolytic markers in the routine chemical identification of irradiated foods. This study was carried out with the view to answering a key question in relation to the fate of irradiated foods post irradiation and during storage; would it still be possible to correctly identify foods as having being irradiated towards the end of their shelf-life? Chemical detection method was employed to closely follow and plot the loss of each of these radiolytic markers throughout shelf-life. Significant levels of DCB and TCB were detected in all irradiated beef samples, which have been stored over 12-month period. Despite the considerable drop in the levels of both markers with time, it was still possible to detect both markers and therefore confirm that the stored samples had in fact been previously irradiated. These reported findings confer additional traceability choice to the global market of irradiated foods that may consequently, raise confidences among concerned parties.

Identification of irradiated crab using EPR

EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156–5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response.

Qualitative and quantitative thermoluminescence analysis on irradiated oregano

Thermoluminescence (TL) dosimetry is one of the physical methods used for the identification of irradiated food, suitable for foods from which silicate minerals can be extracted. The aims of the present work were to apply the TL analysis for a qualitative identification of irradiated oregano, and to set up a quantitative procedure to estimate the original treatment dose on the sample. The experimental results show that the TL analysis allows to distinguish irradiated oregano even seven months after the treatment. The additive dose procedure gives a rough estimation of the treatment dose, but can be helpful when the TL ratio method is unsatisfactory.

Evaluation of Several Dosimeters for Identification of Irradiated Foods Using a 5 MeV Electron Beam.

Electron-beam irradiation facilities are commercially utilized for food irradiation. This study investigates whether dosimeters used to detect gamma-rays can also be used to accurately detect electron-beam irradiation. The irradiation souses for gamma-ray at the Takasaki Institute were used throughout this study. Four kinds of dosimeters, RadiaChromic (RC), GammaChromic (GC), Amber3042 (AM), Radix (RX), and alanine (AL) were irradiated at doses from 0.1 to 60 kGy using a 5 MeV electron-beam (EB) at the Japan Irradiation Service Co. Ltd. (Japan). AL was submitted to the National Physics Laboratory in order to evaluate the doses that AL were absorbed. At low-level dose range, all dosimeters indicated correct values. This means those dosimeters were usable to accurately detect electron beam irradiation. But at higher range they all required correction due to either temperature effects or varying sensitivity to electron-beam exposure. Dose-depth profiles were obtained using ham and cheese samples, in order to check penetration of EB by the calibrated machine.

照射食品検知の現状と将来

The XII th International Meeting on Radiation Processing was held at Avignon March 25 to 30th, 2001. Many methods for identification of irradiated foods were presented in the meeting. The 5 standard methods issued by the British Standard Institutes (BSI) were effective since 1997. Most papers were related to the 5 standards. The papers reported 8 extended applications to foods that are not validated by BSI manuals. Comet assay is a new candidate for the standard. Six applications of comet assay and related assay for 17 foods are presented. Viscosity method for grains and nuts, impedance method for potato, and infrared method for milk products were also reported in the conference.

照射食品の検知―熱ルミネセンス (TL) 法―

照射食品の検知―熱ルミネセンス (TL) 法―

Identification of irradiated food: The current status

There are a number of methods now available for the identification of a range of irradiated foods. Following successful evaluation in interlaboratory blind trials, five standard methods, based on thermoluminescence, electron spin resonance spectroscopy and the formation of hydrocarbons and cyclobutanones, have been submitted to the European Committee of Standardization (CEN) for its consideration. Research is continuing in the development of other techniques and in the future additional methods may become available.

Detection of radiation-induced hydrocarbons in baked sponged cake prepared with irradiated liquid egg

For identification of irradiated food, radiation-induced volatile hydrocarbons (HC) are determined by gas chromatography in the non-polar fraction of fat. However, in complex food matrices the detection is often disturbed by fat-associated compounds. On-line coupling of high performance liquid chromatography (LC) and gas chromatography (GC) is very efficient to remove such compounds from the HC fraction. The high sensitivity of this fast and efficient technique is demonstrated by the example of detection of radiation-induced HC in fat isolated from baked sponge cake which had been prepared with irradiated liquid egg.