Identification of irradiated foods by the thermoluminescence of mineral contamination

Summary This investigation assessed the radiation-induced thermoluminescence (TL) of food minerals for identifying irradiated foods. Mineral contamination, rather than the inherent mineral content, of foods was studied. Positive identification of foods given 1–10-kGy doses depends on the contents and composition of the mineral contamination and the time span between irradiation and TL analysis. All 20 irradiated spice and herb samples could be identified without comparing them with unirradiated material. Three out of 60 lots of spices and herbs examined so far were so pure that the mineral contents were too low to allow TL analysis. If the soil where potatoes are grown contains feldspars, sprout inhibition treatment with 100–200-Gy doses can also be detected for up to one year, using the 90–250° C low-temperature part of the TL spectrum for evaluation.

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Die Identifizierung strahlenbehandelter Lebensmittel anhand der Thermolumineszenz mineralischer Verunreinigungen

Zusammenfassung Gegenstand dieser Untersuchung ist die strahleninduzierte Thermolumineszenz (TL) der in Lebensmitteln enthaltenen Mineralien als Mittel zur Identifizierung strahlenbehandelter Lebensmittel. Untersucht wird nicht der Eigengehalt der Lebensmittel an Mineralien, sondern die Mineralienkontamination. Die positive Identifizierung von Lebensmitteln, die mit einer Dosis von 1–10 kGy bestrahlt worden waren, ist abhängig vom Gehalt und der Zusammensetzung der Mineralienkontamination sowie von der Zeitspanne zwischen Bestrahlung und TL-Analyse. Noch nach Ablauf von maximal einem halben Jahr konnten sämtliche Gewürzund Kräuterproben (insgesamt 20 Stück) ohne irgendwelche Vergleiche mit unbestrahltem Material identifiziert werden. Von insgesamt 60 bisher überprüften Losen waren drei so sauber, daß ihr Mineraliengehalt für eine TL-Analyse nicht ausreichte. Wenn der Boden eines Kartoffelfelds Feldspate enthält, kann auch die Keimhemmungsbehandlung der Kartoffeln mit Dosen von 100 bis 200 Gy noch bis nach Ablauf von einem Jahr erkannt werden; für die Bewertung wird dabei der Niedrigtemperaturanteil des TL-Spektrums im Bereich von 90 bis 250 °C herangezogen.

     

Import control of irradiated foods by the thermoluminescence method

Summary A thermoluminescence (TL) method was applied for the import control of irradiated foods. The method is based on the determination of the TL of mineral contaminants in foods. Detection of irradiation was incorporated in official Finnish control procedures in spring 1990. For foodstuffs with a reduced microbe content and in which no fumigant residues are found, possible irradiation is investigated by the TL method. The minerals are separated from the foods in different ways: picking is used for spices; water rinsing for herbs, spices, berries and mushrooms; high-density liquid to separate the organic material from the mineral fraction in seafood; and carbon tetrachloride for foods forming gels with water. To date about 140 food samples have been analysed for control purposes: 50 samples of herbs and spices, 25 samples of berries and mushrooms and 65 samples of seafood. Of these, 14 samples of herbs and spices and 5 samples of seafood were shown to have been irradiated. Differences in TL intensity between irradiated and unirradiated samples were at least 1 and usually 3–4 orders of magnitude.

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Einfuhrkontrolle bestrahlter Lebensrnittel mit Hilfe der Thermoluminescenz-Methode

Zusammenfassung Eine Thermoluminescenz-Methode (TL) wurde für die Einfuhrkontrolle bestrahlter Lebensmittel verwendet. Diese Methode basiert auf der Messung der Thermoluminescenz von in den Lebensmitteln vorhandenen mineralischen Verunreinigungen. Diese Methode, eine Bestrahlung festzustellen, wurde im Frühjahr 1990 in das offizielle finnische Kontrollverfahren aufgenommen. Lebensmittel mit reduziertem Mikrobengehalt, ohne feststellbare Begasungsrückstände werden mit der TL-Methode auf eventuelle Bestrahlung überprüft. Die mineralischen Stoffe werden mit verschiedenen Verfahren aus den Lebensmitteln abgetrennt. Dabei werden bei Gewürzen die mineralischen Partikel manuell entnommen, bei Kräutern, Gewürzen, Beeren und Pilzen werden diese mit Wasser abgespült, bei Meeresfrüchten wird mit hochkonzentrierter Lösung behandelt und das organische Material wird von der anorganischen Fraktion bei Lebensmitteln, die mit Wasser gelieren, mit Kohlenstofftetrachlorid abgetrennt. Bis jetzt sind zu Kontrollzwecken etwa 140 Lebensmittelproben analysiert worden: 50 Kräuter- und Gewürzproben, 25 Beeren- und Champignonproben und 65 Proben von Meeresfrüchten. Dabei konnte bei 14 Kräuter- und Gewürzproben sowie bei 5 Proben von Meeresfrüchten eine Bestrahlung nachgewiesen werden. Zwischen den bestrahlten und den unbestrahlten Proben zeigten sich in der TL-Intensität Unterschiede von mindestens einer, meist jedoch von drei bis zu vier Größenordnungen.

     

Development and single laboratory validation for thermoluminescence detection of irradiated foods using X-ray irradiation

The thermoluminescence (TL) method using X-rays was investigated for the purpose of detection of irradiated food, and the method was validated at a single laboratory level. A small X-ray irradiator was developed as an alternative radiation source for normalization, and X-ray irradiation conditions equivalent to gamma-ray irradiation from (60)Co were established. Gamma-ray irradiated spices were used for the method validation. The detection limits (MDL) and lower limit of integrated TL intensities (MDL×10) for the spices were checked and the separation of silicate minerals from the spices was confirmed to be sufficient for TL analysis. There was no significant difference in TL glow ratio obtained using two sets of X-ray irradiation equipment including the newly developed equipment. Repeatability and intermediate precision showed no influence of analysts, X-ray irradiation equipments, or measurement days on the TL ratios. From these results, this detection method was validated in a single laboratory.     

Microbiological safety of irradiated foods

This paper attempts to summarize relevant information on microbiological safety of irradiated foods in the light of previous reports of expert committees and current literature references. After a brief survey of the relative radiation resistance of food-borne microorganisms, the importance of microbial load for dose requirement, and the role of post-irradiation conditions, it addresses the following questions: Could selective changes in the microflora, caused by non-sterilizing radiation doses, make known pathogens more likely to occur, or bring into prominence unfamiliar pathogens? Is it probable that 'mutational' (including adaptive) changes might make pathogens more virulent, more harmful, or more difficult to recognize, and could new pathogens arise in this way? Is it possible that development of radiation-resistant strains might render the antimicrobial irradiation processes ineffective? The present survey of relevant scientific evidence related to these questions reaffirms the basic conclusion of earlier reviews, that microbiological safety of irradiated food is fully comparable with that of foods preserved by other acceptable preservation methods. Similar to other preservation processes, gains in microbiological or keeping quality attained by food irradiation can be and must be safeguarded by proper control in the food irradiation facilities and by proper care of the product before and after processing.     

Applicability of thermoluminescence techniques to identify irradiated seafoods using different methods of mineral separation: An interlaboratory blind trial

Thermoluminescence (TL) technique for identifying γ-irradiated (0–10 kGy) anchovies (dried), kelp (dried), and mackerel (fresh) was validated in an interlaboratory blind trial. Different irradiation detection laboratories were involved by using 2 methods of mineral separation (density separation and acid hydrolysis) for the analysis. Key TL parameters, including the TL glow-curve shape, intensity, and the TL ratio (TL₁/TL₂) were used to characterize the irradiation status. All irradiated samples exhibited an intense TL peak at approximately 200°C, which was absent in non-irradiated samples. TL glow curve interpretations were also confirmed by determining the TL ratio. Different participating laboratories reported 89–100% correct results. Both methods of mineral separation were equally effective; however, some variation was observed in the results from different laboratories for irradiated mackerel, which might be due to a lack of isolated minerals, differences in personnel expertise, and different TL instruments.     

Increased supercooling in irradiated foods

The supercooling temperatures of γ-irradiated and control cod, mushroom, and two chicken samples were measured using a Differential Scanning Calorimeter (DSC). The mean supercooling temperatures were significantly lower in three out of the four samples of the irradiated foods, suggesting that the effect might be the result of irradiation. There was high variability between samples and a possible dependence on spoilage which require further investigation to assess the potential of the test for detecting irradiated foods.     

热释光法在辐照食品检测中出现假阳性问题的探讨

目的探讨热释光法在辐照食品检测中出现假阳性的问题。方法按照标准EN1788-2001《食品与硅酸盐矿物隔绝的食品的辐射检验热致发光法》,采用热释光法对深海鱼加工产品进行辐照食品检测。结果与花椒粉等典型辐照样品不同,深海鱼加工产品虽然检测结果为阳性,但其谱图与典型辐照样品谱图存在一定差异。主要表现为一次发光曲线中,典型辐照样品谱图的发光峰下降舒缓,峰型符合正态分布;而深海鱼加工产品的发光峰下降陡峭,并不符合正态分布。据此,怀疑热释光法对深海鱼加工产品的检测分析结果实为假阳性。结论建议在对深海鱼产品进行辐照检测时,谨慎选用热释光法或采用其他检测方法如气相色谱分析碳氢化合物法进行复验。     

An improved method to identify irradiated rice by EPR spectroscopy and thermoluminescence measurements

Minimal change in irradiated foods with low dose treatment makes the identification process a difficult task. Two independent physical methods, electron paramagnetic resonance (EPR) spectroscopy and thermoluminescence (TL) detection were employed for detection of irradiation treatment on Basmati rice. EPR investigation of 0.5–2.0 kGy irradiated rice samples showed a short lived, asymmetric, dose dependent spectrum (g = 2.005), characterised by the radicals of irradiated starch. However, this signal disappears with time. The present work explores the possibility to identify irradiated rice by the relaxation characteristics and thermal behaviour of the radicals. This study reports for the first time that the different microwave saturation behaviours of the signal (g = 2.004) in irradiated and non-irradiated rice samples provide an important clue to identify radiation treatment beyond the period when the radiation specific EPR spectral lines have disappeared. TL investigation involving scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) of the poly-minerals isolated from the rice samples allowed to discriminate clearly between irradiated and non-irradiated samples even after a prolonged period of storage.     

The contamination of vegetable foods by lead containing street dust

To assess the contamination of fruit and vegetables by lead-containing road dust, products displayed in the open air and in retail shops, respectively, were analysed for lead content. The lead exposure within the range of the retail shop was characterized by an aerosol with 0.2-2.5 microgram/m3 and a sedimentable lead dust of 2.13-6.55 mg/m2-30 d. The lead content of the products displayed in the open air was some 0.5 to 6-fold higher. This difference was statistically significant. 92-100% of the lead dust could be removed from the products by washing with water. Increased lead contents were also found on fruit stored in a cellar (0.66 and 0.42 p.p.m., respectively) near a parking place. In consideration of the proportion of these foods in the diet consumed, no health hazard to the population can be deduced from these data; but in single cases, a temporary rise of the blood-lead level may occur. Covering fruit and vegetables presented in the open air with thin-sheet plastics or selling such products in plastics bags will prevent contamination.     

Gluten contamination of cereal foods in Canada

Persons suffering from celiac disease (CD) must avoid foods containing gluten or those contaminated with wheat, barley, or rye. This study was designed to estimate gluten contamination of cereal-based foods available in Canada, whether labelled gluten-free or not. About half of the 148 foods sampled were labelled as gluten-free. According to R5-enzyme-linked immunosorbent assay (ELISA), twenty-three cereal-based foods (or 15%) contained more than 20 mg of gluten per kg, including sixteen regular and seven gluten-free foods, the latter being the least contaminated. When used in combination with R5-ELISA, AOAC-ELISA (not detecting barley) was a simple and efficient tool to roughly estimate the nature of the gluten contamination, which was later confirmed by real-time polymerase chain reaction for barley, and wheat/barley/rice. Rice-, corn- or quinoa-based foods were the safest for celiac patients. In addition to misleading food labelling for both gluten-rich and gluten-free foods, critical issues for persons with CD included foods made with oats or buckwheat (contaminated with wheat and barley gluten) in addition to those, such as breakfast cereals, specifically enriched with barley malt ingredients.     

Effect of contamination of foods by Aspergillus flavus on the nutritive value of protein

The effect of aflatoxin was measured on the protein quality of peanut meal (PNM) and fish meal (FM) Total protein efficiency, protein efficiency ratio, net protein utilisation, examination of the histopathology of the liver, ileal digesion of amino acids and plasma amino acid concentration were used as bioassays together with chemical score (CS), dye binding capacity (DBC), essential amino acid index (EAAI), and discriminant computered PER (DC-PER) as chemical methods. In trial 1, aflatoxin-free PNM was compared with infected PNM at graded levels of toxin when fed to chickens and ducklings. In trial 2, various mixtures of PNM and FM at a constant aflatoxin level (280 μg kg^?1) were fed to compare the effects of aflatoxin on proteins of differing quality. Ducks were more sensitive to the toxin than chickens, as indicated by deterioration of protein quality, and the effects on growth and the histological appearance of the liver were magnified on diets of low quality (PNM), but not of high quality (FM). Contamination of PNM resulted in progressive increase in DBC and, to a lesser extent, in DC-PER, while EAAI and CS were not affected. The importance of these findings lies in the problems of mould contamination of animal feedstuffs in humid, tropical conditions, which may affect the more sensitive animals, and may not be detected by chemical methods of measuring protein quality, nor by bioassay on chickens, if the levels of contamination are low.     

Trace contamination of foods by migration from plastics packaging—A review

Plastic packaging often contains many components in addition to the base polymer. Additives are required both for the manufacturing process to give acceptable results and for the finished product to have the desired characteristics. Furthermore, decomposition products may arise from these additives, while the base polymer itself will contain monomer and oligomers in addition to traces of constituents of the polymerisation mixture (such as catalysts) and any decomposition products arising from these. Printing inks, laminates and their adhesives further complicate the picture. Consequently, the final product can contain a multitude of components at all levels from traces to perhaps 20–30% by weight.Where these components are of low molecular weight, a potential exists for their migration into packaged foods. It is essential, therefore, that manufacturers and users of plastic packaging intended for food contact be aware of the chemical nature of the range of potential migrants expected from a given polymer/additive/food system and have some understanding of the underlying mechanisms and kinetics of migration.This paper presents an overview of current knowledge of migration. After an outline of the physical basis of migration, the concept of—and problems inherent in—measuring overall migration are described, followed by a discussion of selected specific migrants.Although information on contamination from residual monomers forms the bulk of the available literature on specific migrants, migration of other base polymer constituents and of non-volatile plastics additives and their decomposition products can be of importance and is reviewed here.     

桶装矿泉水的藻类污染及防治措施

桶装矿泉水中出现的藻类污染现象，讨论了藻类污染的途径，对灭菌方法进行了研究，试图寻求一种快速有效的灭藻消毒工艺．     

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

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.     

Gluten contamination in manufactured gluten-free foods in Turkey

ABSTRACT

Gluten contamination in manufactured gluten-free foods (mGFFs) is a major health, well-being and economic issue worldwide for both mandatory and voluntary GFF-consumers. Although scarce, a number of surveys have shown that up to 21.5 % of mGFFs in circulation in the market are contaminated with gluten. However, at the present time there is no published work reporting gluten contamination in mGFFs produced in Turkey. In this paper miscellaneous mGFFs produced in Turkey were analysed for gluten concentration (G) to fill this knowledge gap, and to compare the situation in Turkey with worldwide efforts on this issue. A total of 200 mGFFs from 8 product categories (snack, pasta, bread, cookie, cracker, farina, traditional and others), and manufactured using 7 main ingredients (cereal mixture, buckwheat, corn, rice, locust bean, potato, and others) were analysed. A significant portion of mGFFs (17.5 %) were contaminated with gluten and therefore unacceptable as being GFF. The results point to buckwheat as the main cause of this contamination. If buckwheat is excluded, the ratio of unacceptable mGFFs dramatically decreases to 6.3 % and probably to 1.8 %, which are comparable figures to those reported for other countries. Almost all countries are subjected to the same regulations on GFFs, and the problem of gluten contamination could readily be solved to a great extent if pre-market measures are mandated. Enforcing mGFF-producers to screen their raw materials and final products to detect the presence of gluten, and preventing the release of contaminated mGFFs into the market would be a practical measure in favour of all stakeholders involved in GFF-consumption.     

利用矿质元素“指纹”识别葡萄酒原产地

综述了目前葡萄酒矿质元素的分析测定方法及在原产地"指纹"识别方面的研究现状,介绍了多元素组成和同位素比值在葡萄酒原产地识别上的研究实例,预测和展望了该领域可能的研究趋势及国内相关研究的前景.     

辐照食品检测技术方法与标准

对辐照食品检测的目的、原理以及建立检测方法的要求进行系统归纳,对不同辐照食品检测方法和国内外标准制定情况进行比较.发现目前还不存在一种适用于所有辐照食品检测的方法,现有的方法各有优劣.同时并指明我国辐照食品检测技术今后的研究和发展方向.     

深圳市市售食品中镉污染状况调查

目的了解深圳市市售食品中镉污染状况,为采取有针对性的控制措施提供科学依据。方法采取分层随机抽样方法,采集2017年深圳市市售水产品、蔬菜及食用菌、畜肉类等19类2 410份食品样品,用电感耦合等离子体-质谱(ICP-MS)法检测食品中镉含量,检测结果按GB 2762—2017《食品安全国家标准食品中污染物限量》及NY 659—2003《茶叶中铬、镉、汞、砷及氟化物限量》进行评价。结果 2 410份样品中镉检出率为48.7%(1 174/2 410),超标率为7.9%(190/2 410)。水产品中镉污染最严重,超标率为24.0%(187/780);其中双壳类镉含量最高,中位数含量为0.340 mg/kg,超标率为34.1%(184/540)。水果超标率为1.3%(1/80),蔬菜及菌类超标率为0.7%(2/270)。不同来源样品超标率差异有统计学意义(P0.05)。结论深圳市市售水产品、水果、蔬菜及菌类中存在镉含量超标现象,尤其水产品中镉污染严重,建议相关部门采取有效措施,加强监管力度,保障食品安全。     

Detection of mineral oil and paraffin in foods]

The author describes a thin-layer chromatographic method for the detection of small amounts of mineral oil and paraffin in foods. Fatty acids, glycerides, fat-soluble vitamins, sterols, and unsaturated hydrocarbons remain at the starting point. This method permits to detect as little as 0.2 mug of mineral oil or 20 mug of mineral oil/kg of food in low-fat products. 0.01% of mineral oil-like contaminants may be detected in fats.