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Various approaches in EPR identification of gamma-irradiated plant foodstuffs: A review
Abstract
Irradiation of food in the world is becoming a preferred method for their sterilization and extending their shelf life. For the purpose of trade with regard to the rights of consumers is necessary marking of irradiated foodstuffs, and the use of appropriate methods for unambiguous identification of radiation treatment. One-third of the current standards of the European Union to identify irradiated foods use the method of the Electron Paramagnetic Resonance (EPR) spectroscopy. On the other hand the current standards for irradiated foods of plant origin have some weaknesses that led to the development of new methodologies for the identification of irradiated food. New approaches for EPR identification of radiation treatment of herbs and spices when the specific signal is absent or disappeared after irradiation are discussed. Direct EPR measurements of dried fruits and vegetables and different pretreatments for fresh samples are reviewed.
... In this sense, it is important to be able to identify irradiated and nonirradiated species and, if possible, to identify the level of irradiation, in order to contribute to consumers' food safety. Aleksieva and Yordanov (2018) explained that the difficulty of differentiating between irradiated and unirradiated species comes from the fact that there is only a single line before and after radiation treatment. ...
... An ESR spectrum characteristic of a food of irradiated plant origin is associated with the liberation of free radicals induced by cellulose, receiving the name "cellulose-like" (Aleksieva & Yordanov, 2018). The cellulose-like EPR spectrum in irradiated paprika is considered as consisting of a nonspecific central line and specific doublet of cellulose signal (Kispéter et al., 2003). ...
... It should be taken into account that cellulose-like ESR spectra may not be detected in irradiated spices with low cellulose content, or at irradiation doses lower than 10 kGy. In addition, their spectra can disappear 70 to 90 days after irradiation, depending on the storage conditions, having as an irradiation identifier only the increase in intensity of the natural singlet line, which is not proof of high irradiation energy (Aleksieva & Yordanov, 2018). For this reason, it is important to develop adequate protocols for the authentication of irradiated spices using ESR and to explore ESR imaging to obtain a more realistic distribution of paramagnetic species. ...
Food fraud in herbs and spices is an important topic, which has led to new technologies being studied as potential tools for fraud identification. Nontargeted technologies have proven to be a useful tool for the authentication of herbs and spices. The present review focuses on the use of near‐infrared, hyperspectral imaging, Fourier‐transform infrared, Raman, nuclear magnetic resonance, and electron spin resonance spectroscopy for the authentication of spices, which includes the determination of origin and irradiated spices and the identification of adulterants. The methods developed based on vibrational spectroscopy combined with chemometric techniques seem to be promising tools for determining the presence of adulterants and contaminants in herbs and spices. On the other hand, nuclear magnetic resonance seems to be the most efficient technology to determine the origin of herbs and spices although, for some cases, studies with near‐infrared spectroscopy can be a viable substitute. Electron spin resonance spectroscopy is the technique par excellence used for the authentication of irradiated herbs and spices, so its use should be expanded to many more spices’ varieties. Portable devices are preferred by those involved in the food industry, due to its manageability and low cost. Data fusion and big data are shown as promising tools for spice fraud control. In conclusion, spectroscopic techniques show a great efficiency to authenticate spices, although their evaluation must be expanded to other spice varieties, to new strategies of data analysis (as data fusion and big data), and to the use of portable devices.
... The electron spin resonance (ESR) measurements were carried out after irradiation (zero time) and after 6 months on the same samples. The free radicals created electron paramagnetic resonance (EPR) signals were recorded at room temperature by an X-band EMX spectrometer (Bruker, Germany) located at NCRRT, Cairo, Egypt, using a standard rectangular cavity of ER 4102 (Gohn, 1986;Aleksieva and Yordanov, 2018). ...
... The presence of free radicals in the non-irradiated fruits is due to the presence of sugar crystals and cellulose particles naturally in the date fruits (Chiappinelli et al., 2019). In addition, the method of fruit dehydration, which depends on the high temperature, also affects the formation of free radicals, and these radicals are difficult to recombine due to the crystalline structure of the sugar molecules (Aleksieva and Yordanov, 2018;Kuvykina et al., 2022). The signal of free radical intensity was significantly higher in the kernel of the dates in comparison to other parts. ...
Cadra cautella is a serious insect pest of stored figs and dates. The irradiation sensitivity of different development stages of C. cautella and large-scale testing of the proposed irradiation quarantine doses (50–500 Gy), were investigated. The impact of a PI dose of 400 Gy on the physiochemical and microbiological quality of dry dates (Bartamoda cv.) stored at room temperature was also investigated. An irradiation dose of 100 Gy prevented egg hatching in the F1 generation when 1–3 days old eggs were irradiated. Irradiation doses of 200 and 300 Gy prevented adult emergence when 2 nd and 4 th instar larvae were irradiated. When the pupae stage was irradiated, an irradiation dose of 400 Gy prevented the hatchability of F1 generation, indicating that this stage was the most radio-tolerant. The results of large-scale testing of the proposed phytosanitary irradiation dose (400 Gy) applied to 18, 0000 pupae resulted in no reproduction (zero hatching of F1 generation). There were no significant differences in the physiochemical properties of stored dates during the storage period at room temperature. Stable ESR signal intensity was recorded for 6 months in all parts of the irradiated fruits, and the intensity was highest in the kernel. The PI dose of 400 Gy also slightly reduced all microorganisms' counts. In conclusion, the dose level of 400 Gy stopped the reproduction potential of C. cautella . and they maintained the quality characteristics of dry date Bartamoda fruits during storage at room temperature for 6 months in tightly closed packages.
... Alternative methods for gamma-irradiated botanical foodstuffs are thermo-luminescence (TL), photo-stimulated luminescence, gas chromatography (GC), direct epifluorescent filter technique/the aerobic plate count, and DNA comet assay. GC and TL are basic methods, while others are for screening use (Aleksieva and Yordanov, 2018). Luminescence applicability as a detection method is attributable to stimulation, from the formerly exposed mineral component of the foods to ionizing radiation. ...
... Similarly, for lemon samples, the lower dose sample (0.4 kGy) was indexed in proximity to the control on day 0, but easily distinguishable on 20th day. Likewise, portable EPR for customary analysis of irradiated foodstuffs equates to set-up ease and operability, including purpose-based protocols, applications, and reliable calibration (Aleksieva and Yordanov, 2018). Analysis methods for irradiated comestibles are continually researched. ...
The trend for healthy food and lifestyle has enabled consumers to include fruits and vegetables in their daily diet.
Fruits and vegetables are vulnerable to rapid deterioration while improper management of fresh produce also
adds to unfruitful disposal causing environmental pollution and economic problems resultantly. Also, the consumer refusal of chemical additives and losses of the food bioactive compounds due to thermal processing has
attracted the attention of the research fraternity to look for better alternatives. Ionizing radiation treatment of
fresh produce is a non-thermal approach that holds the potential to stretch the shelf-life of fruits and vegetables
with numerous benefits over thermal approaches. Irradiation is a physical method of food preservation apt for
microbial inactivation, shelf-life improvement, and sprout inhibition without nutritional losses and chemical
residues. Ionizing radiation treatment of horticultural produce involves exposure to radiations from sources viz.
X-rays, gamma-rays, electron beam. Reviewing the performances of ionizing radiation for perishable food systems, the current article has been summarized to provide an insight into the concept, application, its effects,
together with a market outlook covering consumer attitude and pertaining legislations. Furthermore, it also
provides a gleam into the future perspective of the technology to nurture the agro-food realm.
... This process damage the microbial DNA inactivating the cell ( Fig. 1 ). Irradiated foods do not become radioactive and are considered safe ( Aleksieva & Yordanov, 2018 ). Although the highest dose allowed for commercial use is 10 kGy, substantially lower doses are sufficient for pathogen destruction (1-5 kGy) and delayed ripening and senescence of fruits and vegetables (0.2-0.5 kGy) ( Loro, Botteon & Spoto, 2018 ;Frimpong, Kottoh, Ofosu & Larbi, 2015 ). ...
... Irradiated products must be labeled as such on their packaging. Methods such as electron paramagnetic resonance spectroscopy can identify whether the food received ionizing radiation, providing greater consumer safety and facilitating the control of the technique ( Aleksieva & Yordanov, 2018 ). ...
In recent years, minimally processed fruits and vegetables have gained widespread consumer attention due to the need for a convenient yet healthy diet. As several factors can affect the shelf life of minimally processed products, it is essential to use preservation technologies that maintain the freshness of fruits and vegetables ensuring consumer health. In the second part of this review, the main physical preservation methods including heat treatments, refrigeration, irradiation, high pressure, ultraviolet radiation, and electrolyzed water are discussed in terms of their advantages, disadvantages, and applications. Advances in packaging for minimally processed products are also explored, such as active and intelligent packaging, edible films and coatings, and vacuum packaging. Defining the operational parameters related to treatment time and dose/intensity appropriate is one of the greatest difficulties in the application of physical methods. Therefore, these factors must be carefully evaluated, as must the sustainability and economic viability of each method.
... Food irradiation should be performed not only to ensure microbiological safety of food product but also to limit the chemical transformations caused by radicals, which may have a negative effect on the energy value, as well as biochemical and organoleptic properties of the product as a whole [11][12][13][14][15][16][17][18][19][20][21][22][23]. For dry products, such as tea, spices, powders, etc., it is necessary to apply the EPR method to control the chemical changes caused by free radicals [12][13][14][15]. ...
... Food irradiation should be performed not only to ensure microbiological safety of food product but also to limit the chemical transformations caused by radicals, which may have a negative effect on the energy value, as well as biochemical and organoleptic properties of the product as a whole [11][12][13][14][15][16][17][18][19][20][21][22][23]. For dry products, such as tea, spices, powders, etc., it is necessary to apply the EPR method to control the chemical changes caused by free radicals [12][13][14][15]. However, when it comes to foods high in moisture, detecting the fact of irradiation using the EPR method is difficult due to diffusion and further disappearance of free radicals [16]. ...
... Food irradiation should be performed not only to ensure microbiological safety of food product but also to limit the chemical transformations caused by radicals, which may have a negative effect on the energy value, as well as biochemical and organoleptic properties of the product as a whole [11][12][13][14][15][16][17][18][19][20][21][22][23]. For dry products, such as tea, spices, powders, etc., it is necessary to apply the EPR method to control the chemical changes caused by free radicals [12][13][14][15]. ...
... Food irradiation should be performed not only to ensure microbiological safety of food product but also to limit the chemical transformations caused by radicals, which may have a negative effect on the energy value, as well as biochemical and organoleptic properties of the product as a whole [11][12][13][14][15][16][17][18][19][20][21][22][23]. For dry products, such as tea, spices, powders, etc., it is necessary to apply the EPR method to control the chemical changes caused by free radicals [12][13][14][15]. However, when it comes to foods high in moisture, detecting the fact of irradiation using the EPR method is difficult due to diffusion and further disappearance of free radicals [16]. ...
Radiation treatment of food products carried out to increase their shelf life can result in chemical transformations initiated by free radicals. Volatile compounds (alcohols, aldehydes, ketones, etc.) formed, in particular, as a result of lipid oxidation, impair the organoleptic properties of products. Method of gas chromatography-mass spectrometry (GC-MS) makes it possible to identify the fact of food processing by detection of volatile marker compounds: in the case of meat products, the existing standard brings under regulation detection of 2-alkylcyclobutanones, however, the products with a reduced fat content, such as turkey and chicken, require an alternative marker. The results of GKh-MS study revealed the dependence of microbiological parameters and the content of various volatile organic substances in chilled turkey meat on the dose of electron radiation. It is shown that the total amount of alcohols, ketones and aldehydes (11 compounds) decreases exponentially with an increase in the absorbed dose. An increase in the radiation dose leads to a higher content of carbonyl compounds (aldehydes and acetone), which results in a specific taste and smell of the irradiated products. At the same time, the acetone concentration increases linearly with the absorbed dose, which makes it possible to use acetone as a potential marker of the degree of irradiation of low-fat meat products. Irradiation in the «working» doses (0.5 – 1 kGy) significantly suppresses the pathogenic microflora and keeps the organoleptic properties of the product.
... Absorbed-dose estimation was performed through the calibration of PSL and ESR signals of the spice mixtures according to the applied doses of E-beam irradiation at 0, 6, 10, and 14 kGy (Aleksieva & Yordanov, 2018). ...
... Disordering of the scatter plots demonstrated goodness of fit of linear fitted models. Same doseresponse calibration curve method was reported by Aleksieva and Yordanov (2018) for identification and dose evaluation of irradiated foodstuffs of plant origin. ...
Spice is a highly susceptible to microbial contamination and its microbial decontamination by irradiation has been increasing worldwide now. Therefore, a reliable detection method for irradiated food is required in compliance with existing labeling regulations. Two different commercial spice-mixtures samples (A and B) were subjected to electron beam (E-beam) irradiation at 0–14 kGy, for which four different analytical approaches were employed: photostimulated luminescence (PSL), electronic nose (E-nose), electron spin resonance (ESR) spectroscopy, and fourier transform infrared (FTIR) spectroscopy. As screening trials, PSL analysis revealed negative results from non-irradiated samples (sample A) (<700 photon counts/60 s: PCs), while positive results from irradiated samples (>5000 PCs/60 s). E-nose approach through principal component analysis also showed a clear discrimination in their flavor patterns between non-irradiated and irradiated samples. The above screening results were effectively validated through determination of radiation-induced crystalline sugar signals by ESR spectroscopy. However, FTIR spectra showed that no significant alterations were observed in functional groups of spice samples upon irradiation. These trials of detection for unknown spice mixtures demonstrated that sample B was found to be irradiated without any labelling on commercial product packages in markets, that was assured through standard PSL and ESR analyses.
... The first step involves creating a uniform method for classifying herbs and guaranteeing efficient quality control procedures. This procedure entails keeping active ingredients or indicators at steady, reliable concentrations in herbal medicines [85]. Its objective is to minimize variations among batches and ensure that each product meets predetermined standards for quality [86]. ...
High-performance liquid chromatography (HPLC) is widely regarded as one of the most effective and adaptable methods for separating and analyzing the components of herbal mixtures. It is utilized to identify and quantify phyto-components within these mixtures. This chapter focuses on the utilization of HPLC techniques, including ultra-performance liquid chromatography (UPLC) or ultra-high-performance liquid chromatography (UHPLC), in the analysis of various herbal products. It provides several specific examples of protocols for such analysis and offers a brief overview of available HPLC techniques and methods. Additionally, this chapter includes step-by-step protocols for the chemical profiling or fingerprinting of herbs, herbal mixtures, and herbal products.
... One important application of EPR is monitoring the radiation dose of food products, cosmetics, and drugs after their sterilization via ionizing radiation of gamma-and X-rays or electron beams [1][2][3][4]. It was found that gamma rays generate paramagnetic centers inside the bone fragments contained within meat products which has led the European Committee for Standardization to adopt EPR as one of the methods employed to identify irradiated food [5]. EPR has also been applied to detect radicals generated in antibiotics like piperacillin, ampicillin, and crystalline penicillin after their sterilization with gamma-irradiation which may potentially reduce the pharmacological activity and alter the pharmacokinetic properties of the drugs. ...
Electron paramagnetic resonance (EPR) spectroscopy is an essential tool to investigate the effects of ionizing radiation, which is routinely administered for reducing contaminations and waste in food products and cosmetics as well as for sterilization in industry and medicine. In materials research, EPR methods are not only employed as a spectroscopic method of structural investigations, but also have been employed for detection of changes in electronic structure due to radiation damage from high energy X-rays, for example, to monitor radical formation inside biomolecules caused by X-ray irradiation at carbon, nitrogen, and oxygen K-edges at synchrotron facilities. Here a compact EPR spectrometer, based on EPR-on-a-chip (EPRoC) sensor and a portable electromagnet, has been developed as a solution for monitoring radiation damage of samples during their investigation by X-ray absorption spectroscopy (XAS) at synchrotron facilities. A portable electromagnet with a soft iron core and forced air temperature stabilization was constructed as the source of the external magnetic field. The sweep range of magnetic field inside the most homogeneous region of the portable electromagnet is 12–290 mT. The compact spectrometer performance was evaluated by placing the EPRoC sensor inside either a commercial electromagnet or the portable electromagnet to record the EPR spectrum of tempol, irradiated alanine, and dilithium phthalocyanine (Li2Pc). The potential performance of the portable spectrometer for the detection of radiation damage in organic compounds and transition metal-containing catalysts during XAS measurements in both fluorescence and transmission modes was calculated with promising implications for measurements after implementation in a synchrotron-based XAS spectrometer.
... EPR spectroscopy has demonstrated its efficacy as a precise and dependable methodology for the dosimetric assessment of pharmaceuticals subjected to irradiation [9]. Numerous research endeavors have elucidated the structural characteristics and radiation susceptibilities of free radicals generated within irradiated pharmaceuticals, food products and amino acid derivatives through the application of EPR spectroscopy [10][11][12][13][14][15]. In the investigation involving the irradiation of raw ifosamide drug material using gamma radiation, a computed g value of g = 2.0030 was established. ...
This study aims to investigate the spectroscopic, dosimetric, and stability properties of free radicals generated within 4-piperidinecarboxylic acid (4PCA) sample due to gamma irradiation within the 2–20 kGy range, utilizing electron paramagnetic resonance (EPR) spectroscopy. To achieve this goal, the EPR signals of the samples were studied in relation to microwave power, ranging from 0.01 to 50 mW, at room temperature. The investigation revealed that γ-irradiation induces the formation of –CH2ĊCH2CH2– (radical I) and –ĊHN– (radical II) radicals within the 4PCA compound. Hyperfine structure constants and g values were also determined for the radicals. The optimal agreement between experimental and computed results within the dose range of 2–20 kGy was achieved using polynomial and linear functions. Experimental measurements were undertaken under varied temperature conditions (123–323 K) to study the dosimetric features of free radicals generated as a consequence of gamma irradiation. Furthermore, an investigation into the time dependency of signal intensity within the irradiated sample was conducted, with the objective of analyzing the long-term stability characteristics of the free radicals present.
... The first step is to built standardization and identification of herbs for effective quality control measures. Standardization and identification of herbs involve establishing consistent and reliable levels of active compounds or markers in herbal medication products (Aleksieva and Yordanov, 2018). It aims to minimize batch-to-batch variability and ensure that each product meets predetermined quality standards (Ketai et al., 2000). ...
This manuscript provides an in-depth review of the significance of quality control in herbal medication products, focusing on its role in maintaining efficiency and safety. With a historical foundation in traditional medicine systems, herbal remedies have gained widespread popularity as natural alternatives to conventional treatments. However, the increasing demand for these products necessitates stringent quality control measures to ensure consistency and safety. This comprehensive review explores the importance of quality control methods in monitoring various aspects of herbal product development, manufacturing, and distribution. Emphasizing the need for standardized processes, the manuscript delves into the detection and prevention of contaminants, the authentication of herbal ingredients, and the adherence to regulatory standards. Additionally, it highlights the integration of traditional knowledge and modern scientific approaches in achieving optimal quality control outcomes. By emphasizing the role of quality control in herbal medicine, this manuscript contributes to promoting consumer trust, safeguarding public health, and fostering the responsible use of herbal medication products.
... As shown in Figure 1b and 1c, the spectral patterns of Prednol and Ventolin following irradiation with 500 Gy and 25 kGy are remarkably similar. Their spectra centered at g = 2.004, which is in good agreement of the complex signal arising because of sugar-like radicals formed in irradiated foodstuffs containing sugar crystals (20,21) . Considering that both drugs contain lactose as an excipient, it was thought that the lactosederived radical was primarily responsible for forming this spectral pattern. ...
Among many sterilization methods, radiosterilization is a preferred method in the pharmaceutical industry because of its advantages. However, the detection of radiosterilization of drugs is a growing concern for many government regulatory agencies around the world because of changes in the drug’ss structure because of exposure to radiation. Electron Paramagnetic Resonance (EPR) proved to be a very sensitive technique to discriminate between irradiated and non irradiated drugs and detect radicals for days even to years. In this study, the focus is on the detection of radiosterilization of irradiated three asthma drugs (Airfix, Ventolinand Prednol) by using EPR spectroscopy. Regarding the commercial aspect so fdrugs, it was found that radical scan be detected at least 2 y after irradiation. Therefore, paramagnetic centers formed by the effect of radiation in the samples were determined and th e stability of these centers was examined for 2y byperforming the fading study.
... There are many EPR studies examining the structures and radiation sensitivities of free radicals formed after irradiation. [8][9][10][11][12][13][14][15][16]. In the study in which the paramagnetic characterization and dosimetric properties of Airfix, an asthma drug, were examined; it was stated that after irradiation, very stable radicals of the alkyl-type were formed [17]. ...
In this study, spectroscopic, dosimetric and stability characteristics of free radicals formed in acetazolamide (ACE) sample as a result of gamma irradiation in the range of 0–15 kGy were determined using electron paramagnetic resonance (EPR) spectroscopy. For this purpose, by interpreting the spectra of the sample in the 0–100 mW microwave power region, it was determined that two different radicals were formed in the sample. The structures formed after irradiation were attributed to CH3OṄ-(radical I) and -OSOṄH (radical II) radicals. The g-values, hyperfine coupling constants and spectrum contribution ratios of these radicals contributing to the experimental spectrum were also calculated. It has been determined that radical II is quite stable both at high temperature and after a long storage period.
... The range of the compounds considered to be "natural products" is broad and in this review it is restricted to extracts and isolated compounds. It will not include the vast array of EPR literature on the photosystems (Britt et al., 2004;Un et al., 2001), irradiated food (Aleksieva et al., 2018), seeds (Barbana et al., 2013), shells (Kavetskyy et al., 2022), and clays (Götze et al., 2002). ...
Background: Applications of electron paramagnetic resonance (EPR) spectroscopy to natural product research have proven useful to understand the properties of natural product extracts and their intrinsic compounds. There are few reviews on this subject written as an initial introduction. Aims: To provide an explanatory review of EPR spectroscopy applied to natural products research. Methods: The search for this review was carried out in the following databases: SciFinder, Google Scholar, PubMed, MEDLINE, and Science Direct, with particular emphasis on publications from the last decade. Results: The articles chosen typically used EPR to provide qualitative and quantitative data of radicals or the action of radicals in natural product research. Studies include the measurement of radical scavenging capacity, singlet oxygen detection and direct detection of semiquinone radicals in extracts. Other applications include the study of autooxidation, and photochemical properties. Conclusion: The current trend for use of EPR in natural products research is by far in radical scavenging capacity. A fast array of experimental methods and reaction chemistry are available to tailor for biological context, which is a great advantage of the versatility of EPR. Previous ground-breaking use in detection of semiquinone radicals in extracts has waned, however, given the prevalence for quinones in plants, and cheaper bench top EPR instruments, there must be an opportunity for this to progress further. The current generation of EPR instruments offers new opportunities to probe natural product molecules and extracts with greater resolution.
... Our aim was primarily to characterize the response of the AN4 tomato under a potent radiative pro-oxidant stimulus. ESR spectroscopy, a leading method for evaluating food matrices (Aleksieva and Yordanov, 2018), revealed that, in tomato fruits, high dose gamma radiation mainly induces cellulose radicals, as expected for a plant matrix (Duliu and Bercu, 2017), and showed that AN4 fruits metabolites have a higher free radical scavenging activity compared to wild type ripe fruits. This trait may be very beneficial both in terms of food consumption and in terms of plant resistance to pro-oxidant stimuli. ...
Introduction: Methods for production of fresh, health food are needed in view of long-term, deep-space manned missions. To this end, crops tailored for better performance under non-terrestrial conditions may be obtained by the exploitation of biochemical patterns related to specialized metabolites known to confer protection against environmental challenges and to be beneficial to human health.
Methods: In this work, for the first time, MicroTom plants have been engineered specifically for agrospace applications to express PhAN4 , a MYB-like transcription factor able to regulate the biosynthesis of anthocyanins that influence tomato genes possibly involved in agrospace-relevant functions.
Results: PhAN4 engineering underpinned the genetic background of the dwarf tomato MicroTom while maintaining yield and photosynthetic capacity. PhAN4 expression resulted in the accumulation of anthocyanins and polyphenols, a differential carotenoid profile, increased antioxidant scavenging capacities of fruits compared to the original genotype. Improved ability to counteract ROS generation and to preserve plant protein folding after ex-vivo gamma irradiation was observed.
Discussion: These results highlights that the manipulation of specific metabolic pathways is a promising approach to design novel candidate varieties for agrospace applications.
... These hard and dried peelings were shown to have an excellent potential for the presence of cellulose based radiation-induced triplet signals. Such a fact that seeds, shells or skins of foods could trap radiationinduced cellulose radicals and be used to monitor the radiation exposure of the foods has already been investigated (Aleksieva and Yordanov, 2018). The skins or peelings obtained from the food samples were dry, hard and rich in cellulose contents, and were expected to retain radiation-induced cellulose radicals. ...
Electron Spin Resonance (ESR) spectrometry is a potential technique for detection of irradiated foods like plant foods, which contain cellulosic materials as well as low molecular weight sugars and like the meat and fish, which contain bones. This study is focused on identification of irradiated foods such as tree nuts (pine nuts and walnuts), beans and pulses (red grams, white beans, pinto beans and green peas), and food containing low molecular weight sugars (pan masala and dried dates). The food samples were obtained from Pakistan and exposed to different permissible doses of radiation using electron beam linear accelerator. The control and irradiated samples were kept at room temperature in the laboratory for the record of ESR spectra. For post-irradiation stabilities the food samples were analysed at different intervals of time (15, 90 and 300 days). The controlled samples in case of cellulosic foods showed ESR signal at g0 = 2.004 and irradiated samples were shown with triplet signal indicative of the presence of radiation-induced cellulose radicals. Similarly, in case of Pan Masala and dried dates, a straight signal at zero level was observed for un-irradiated samples and a complex ESR signal was appeared for irradiated samples. The observed radiation-induced signals were dose-dependent and showed an increasing trend with an increase in radiation dose. The comparison of intensities of ESR signals was also carried out along with the study of post-irradiation stabilities of the ESR signals and method proved to be valid for differentiation of controlled and irradiated samples of food.
... Irradiation of food has the potential to replace sodium nitrite, as well as the fumigants ethylene dibromide, ethylene oxide, and methyl bromide. This is crucial because these fumigants may be hazardous to humans and/or have negative impacts on the ozone layer in the atmosphere (4 Currently, ten standards for the identification of irradiated food are in use within the European Union, six of which are primary and four of which are for 'screening' purposes. Three of the most important standards use the EPR spectroscopy approach. ...
In the current study, the EPR signal of both gamma-irradiated shell and kernel of the pistachio is recorded and investigated. The spectrum properties, microwave power dependency of signal intensities, short- and long-term temporal dependencies, and other significant factors are studied. This investigation was done on how varying radiation doses (0–10 kGy) affected the reactions of pistachio shells and kernels. The time dependence of the radiation-induced signal intensity of pistachio showed that the maximum intensity reached about 98.75% and 67% of its original value for shells and kernels, respectively, after the first six hours. These results indicate that EPR is an effective tool for gamma-irradiated pistachio identification and dosimetry, whether employing pistachio shells or kernels.
... There are a number of techniques used to record and control chemical changes in food that occur after radiation treatment [14]. The method of electron paramagnetic resonance (EPR) is actively used for dry foods of plant origin, products containing calcium, cellulose, crystalline sugar, and others [15][16][17]. The thermoluminescence (TSL) and photoluminescence (PL) methods are used for foods that contain silicon, such as seafood, potatoes, onions, and beets [18,19]. ...
One of the most important tasks in the food industry is the search for alternative biochemical markers of radiation treatment in dietary, chilled meat products such as chicken and turkey. Major organic volatile chemicals found in meat products can be precisely identified using gas chromatography coupled with mass spectrometry. In the response to the needs of the food industry, our research team conducted a series of experiments involving the irradiation of chilled poultry meat using an electron accelerator. The experiments showed that the concentration of pure volatile organic compounds in saline solution dropped exponentially with an increase in the irradiation dose, which proves that these chemicals decomposed when exposed to ionizing radiation. However, when turkey meat was exposed to an electron beam with doses up to 1 kGy, the concentration of alcohols, aldehydes, and ketones peaked, only to decrease with an increase in the irradiation dose up to 2 kGy, and then went up slightly when the irradiation dose was within the range from 2 kGy to 10 kGy. To determine the reason behind the nonlinear dependencies of organic compound concentrations in turkey meat on the irradiation dose, we developed a mathematical model that acknowledges the presence of two opposing processes, those of decomposition and accumulation of organic compounds as a result of the decomposition of other compounds that can be found in turkey meat.
... Different methods of chemical analysis are used depending on the type of product. For dry products, the electron-paramagnetic resonance technique is actively applied [12][13][14][15] . This method, however is not applicable to products containing a high amount of moisture, because it does not to detect free radicals after the treatment due to diffusion of radicals. ...
The purpose of this work was to compare the effect of electron and X-ray irradiation on microbiological content and volatile organic compounds in chilled turkey meat. Dose ranges which significantly suppress the pathogenic microflora while maintaining the organoleptic properties of the turkey meat are different for electron and X-ray irradiation. According to the study it is recommended to treat chilled turkey using X-ray irradiation with the dose ranging from 0.5 to 0.75 kGy, while in electron irradiation permissible doses should be within 0.25–1 kGy. Three main groups of volatile compounds: alcohols, ketones, and aldehydes—were found in irradiated and non-irradiated samples of turkey meat. It was found that the total amount of aldehydes, which are responsible for the formation of a specific odor of irradiated meat products, increases exponentially with the increase in the absorbed dose for both types of irradiation. It was established that acetone can be used as a potential marker of the fact of exposure of low-fat meat products to ionizing radiation.
... For instance, with its ability to evaluate free radicals, EPR spectroscopy has been set as a primary tool to identify irradiated foods in 1/3 of the current standards of the European Union. 19 More importantly, EPR spectroscopy is a powerful way to study Ca-rich materials. For example, Ca(II) is the second essential messenger that ensures proper brain function. ...
... Different methods of chemical analysis are used depending on the type of product. For dry products, the electronparamagnetic resonance technique is actively applied [12][13][14][15]. This method, however is not applicable to products containing a high amount of moisture, because it does not make it possible to detect free radicals sometime after the treatment due to diffusion of radicals. ...
The purpose of this work was to compare the effect of electron and X-ray irradiation on microbiological content and volatile organic compounds in chilled turkey meat.
Dose ranges which significantly suppress the pathogenic microflora while maintaining the organoleptic properties of the turkey meat are different for electron and X-ray irradiation. According to the study it is recommended to treat chilled turkey using X-ray irradiation with the dose ranging from 0.5 kGy to 0.75 kGy, while in electron irradiation permissible doses should be within 0.25 kGy-1 kGy.
Three main groups of volatile compounds: alcohols, ketones, and aldehydes were found in irradiated and non-irradiated samples of turkey meat. It was found that the total amount of aldehydes, which are responsible for the formation of a specific odor of irradiated meat products, increases exponentially with the increase in the absorbed dose for both types of irradiation. It was established that acetone can be used as a potential marker of the fact of exposure of low-fat meat products to ionizing radiation.
... It is a clean technology that does not produce chemical residue, waste-water, combustion gases as compared to other methods (Slave, Negut, & Grecu, 2014). Although the irradiated products are not very common in the current human food market due to negative consumer perception, irradiated pet food products is a growing market (Aleksieva & Yordanov, 2018). In the United States, the Food and Drug Administration (FDA) has approved the use of irradiation in both human and animal food products to a predetermined maximum dose (FDA, 2001(FDA, , 2015. ...
Dried sweet potatoes (SPs) are often irradiated for improved safety and shelf life. Formation of irradiation‐derived radicals was analyzed using electron paramagnetic resonance (EPR) spectroscopy. These irradiation‐specific radicals can be used to characterize the irradiation history of dry plant‐based foods containing cellulose and sugars. The signal characteristics (intensity and peak shape) were evaluated at different sample locations (skin and flesh), as a function of sample preparation method (grinding, sieving, and pelletizing). The signal intensity was quantified using a double integration method of the peaks based on the area under the curve. The sieving caused ca. 50% decrease in total signal intensity as compared to nonsieved samples due to loss of cellulose‐based radicals. The flesh of irradiated SP showed complex EPR spectra with multiple satellite peaks of cellulose radicals (333.5 and 338.8 mT) and split peak of dextrose radicals (337.4 mT); while skin spectra were distinctive of cellulose radicals. In this study, we demonstrated the effects of sample composition and preparation method on formation and analysis of irradiation‐specific radicals based on EPR.
Practical Application
In the last decade or so, there have been health concerns related to the consumption of irradiated pet food products. Electron paramagnetic resonance spectroscopy can be used to analyze the irradiation history of dry products containing cellulose and sugar, such as the popular dog treat dried sweet potatoes, to ensure the products were irradiated within safe limits. This work demonstrates that the formation of irradiation‐specific radicals is affected by the sample location (skin and flesh) and moisture content.
... The European Community provides several analytical methods that can be used for the identification of the irradiation treatment. Among the proposed and validated analytical methods (physical, chemical and biological), the electron spin resonance (ESR) spectroscopy is a powerful technique for the identification of irradiated food [10]. Indeed, three standard methods based on ESR have been adopted by the European Committee of Normalization: ...
Food irradiation is used to preserve food from pathogenic microorganisms, deterioration and to extend shelf life. The EU legislation states that any irradiated food or food ingredients must be labeled with the word “irradiated”. The ESR spectroscopy is a powerful tool to enhance official checks; hence, it has been used to detect irradiated hazelnuts. The results from the ESR studies on hazelnuts before and after X-ray irradiation are reported. Before irradiation hazelnuts exhibit one singlet ESR line characterized with a g-factor of 2.0046 ± 0.0006. After irradiation, a typical “cellulose-like” triplet ESR spectrum appears. To investigate the radio-induced free radical stability, the peak-to-peak amplitude of the ESR satellite signals was considered. Fading measurements indicate that the intensity of the ESR spectra of hazelnuts is reduced to about 70% after 30 days. In addition, the microwave power behavior and a dose–response relation were investigated. The study confirmed the applicability of ESR technique to detect irradiated hazelnuts also when a long time after treatment was passed.
... The use of EPR spectroscopy to monitor radicals in γ-radiated foods is a common practice which is very well documented in the literature [31][32][33][34][35][36][37][38][39]. The most of the studies were focused on consumer safety due to the use of this method in some countries for food product sterilization. ...
... 7 Among these, electron spin resonance (ESR) spectroscopy is a method approved in several countries for detecting irradiation in foods containing cellulose (herbs and spices, fruit seeds, and nutshells), meat or fish bones, or crystalline sugar. 8 The method relies on the formation of stable radicals on solid parts of food upon irradiation. 9,10 Clove is the dried aromatic flower bud of the evergreen tree Eugenia caryophyllata Thunb. ...
BACKGROUND
Food irradiation is a widely used technique for improving the safety and shelf life of foods, including most spices. However, growing concerns by consumers about this technique require further investigation on the effects of radiation, both on the safety of the food and on its organoleptic properties. In this work, cloves of diverse origins were submitted to different irradiation doses in a ⁶⁰Co source. The presence of trapped radicals and their time‐dependent decay after irradiation were assessed by electron spin resonance (ESR) spectroscopy. The volatile bioactive composition and the clove oil were evaluated before and after irradiation by gas chromatography time‐of‐flight mass spectrometry.
RESULTS
Results show an increase of the amount of volatiles collected after irradiation, especially of caryophyllene oxide and acetic acid, although these are still minor constituents. No new compound was detected after irradiation. Radicals decay fast, and 60 days after irradiation they were undetectable by ESR.
CONCLUSION
Gamma irradiation showed to be a clean technique for clove decontamination, since no significant change in the aroma or oil compositions was found, and low levels of trapped paramagnetic species, after the initial decay period, were detected upon irradiation. Furthermore, irradiation doses higher than those legally allowed are equally safe. © 2018 Society of Chemical Industry
The present work represented results from a comprehensive study of free radicals and the antioxidant properties of irradiated walnuts. The effects of gamma irradiation on free radical generation and their stability, as well as on the antioxidant activity in walnuts, were investigated by Electron Paramagnetic Resonance (EPR) spectroscopy, Oxygen Radical Absorbance Capacity (ORAC), and Hydroxyl Radical Antioxidant Capacity (HORAC) assays. Walnut samples were irradiated using 60Co at two different doses: 10 and 25 kGy. As a marker for the identification of high-energy radiation treatment, characteristic cellulose radical signals were detected after irradiation and remained observable for over eight months. A significant increase in antioxidant activity was observed at higher irradiation doses, as measured by DPPH free radical scavenging activity, ORAC and HORAC assays.
Turmeric is a functional ingredient commonly used in food, pharmaceutical, and cosmetic products due to its
health benefts and bioactivity, including anti-inflammatory, antioxidant, and anticancer benefts. Irradiation is a
common technique used to decontaminate microorganisms and extend the shelf life of spices. However, there are
scientifc debates over the use of irradiation in food products. This study aimed to assess the effects of ionizing
radiation, including gamma rays and electron beams, on bioactive compounds and microbial characteristics of
turmeric powder. Technically, high-performance liquid chromatography with UV–Vis detection was used to
assess bioactive compounds. Another aim of the present study was to determine free radicals in irradiated and
non-irradiated samples within one month of storage using electron paramagnetic resonance (EPR). Results
showed that gamma and electron-beam irradiations could decrease microbial contamination of turmeric by
approximately 5 and 6 log cfu/g, respectively. Contents of bioactive compounds increased in irradiated samples
and curcumin contents in gamma and electron-beam irradiated samples were 232–248 and 215–266 mg/g dry
weight (dw), respectively. Furthermore, the study detected that free radicals increased in all irradiated samples
immediately after irradiation but decreased over time. Decrease in EPR signals was faster in gamma-irradiated
samples during storage. Numbers of free radicals induced by gamma and electron-beam irradiations were
6.59–4.70, 2.69–1.60, 1.61–1.34, and 0.99–1.05 on days 0, 7, 14, and 21, respectively. After 21 days of storage,
the numbers of free radicals in all non-irradiated and irradiated samples were similar. Therefore, free radicals
induced by irradiations were degraded during storage and eliminated after 21 days.
The use of ionizing radiation offers a boundless range of applications for polymer scientists, from inducing crosslinking and/or degradation to grafting a wide variety of monomers onto polymeric chains. This review in particular aims to introduce the field of ionizing radiation as it relates to the degradation and recycling of cellulose and its derivatives. The review discusses the main mechanisms of the radiolytic sessions of the cellulose molecules in the presence and absence of water. During the radiolysis of cellulose, in the absence of water, the primary and secondary electrons from the electron beam, and the photoelectric, Compton effect electrons from gamma radiolysis attack the glycosidic bonds (C-O-C) on the backbone of the cellulose chains. This radiation-induced session results in the formation of alkoxyl radicals and C-centered radicals. In the presence of water, the radiolytically produced hydroxyl radicals (●OH) will abstract hydrogen atoms, leading to the formation of C-centered radicals, which undergo various reactions leading to the backbone session of the cellulose. Based on the structures of the radiolytically produced free radicals in presence and absence of water, covalent grafting of vinyl monomers on the cellulose backbone is inconceivable.
The United Nations Sustainable Development Goals (SDGs) are 17 objectives that all 193 UN Member States have agreed to achieve by 2030. The UN SDGs provide worldwide guidance for addressing challenges faced by nations. The importance of SDGs is to ensure reliable and sustainable infrastructural solutions that support economic development and human well-being. Radiation Technologies (RTs) use are increasing in developing countries across different areas such as hospitals, research institutes, agriculture, and industries RTs manufacturers offer a warranty that
incorporates maintenance costs. However, there is a problem for these countries due to a lack of internal maintenance mechanisms. Therefore, RTs costs and maintenance remain prohibitive factors in developing countries. IAEA plays an active
part in helping the international community with the 17 SDGs achievements with financial affordability. Although, geopolitical forces, such as climate change, nuclear energy, and pandemic, could impact RTs benefits.
Radiation technology provides a wide range of technologies that can help to promote sustainable development. A country may employ a variety of instruments and ways to accomplish its development goals and difficulties, and radiation technology is rapidly becoming a part of the answer for many countries. It has
the potential to be more cost-effective and ecologically friendly than traditional options, as it consumes less energy and produces less waste. This is critical for all nations, but especially for those with minimal resources. Its varied number of applications makes it ideal for the diverse tasks necessary to achieve the United Nations Sustainable Development Goals (SDGs) and its comprehensive set of goals, which span health and the environment to industry and infrastructure.
In this study, the potential of using OSL (Optically Stimulated Luminescence) reader for fast, easy and inexpensive detection of irradiated black cumin and poppy samples of different brands was investigated under blue light excitation. Three different brands were selected for each food from local markets and each brand of food was irradiated with Co-60 gamma radiation at doses of 1 kGy, 3 kGy, 5 kGy and 7 kGy. OSL signal intensities for each dose were measured both immediately after irradiation and one year after irradiation. While no OSL signal was observed in any of the non-irradiated samples, a significant increase in OSL signal intensities was observed in all samples after irradiation. In addition, it was determined that the OSL signal intensities obtained from some poppy and black seed brands were high enough to allow the determination of irradiation even one year after irradiation.
The headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) technique was used to investigate 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) as X-ray induced markers in irradiated dairy products. For the first time, an intensive study on several types of milk and cheeses, was carried out to evaluate both the suitability of this analytical technique for dairy products and how different factors related to these types of food, such as matrix composition, ripening time and technological processes, can affect 2-DCB and 2-TCB extraction. The results demonstrated that these analytes were identified in all types of irradiated samples, even if 2-TCB showed a lower sensibility than 2-DCB. Moreover, for both analytes, increasing irradiation dose over the experimental range of 0.5–5.0 kGy, a linear response was observed in all the matrices studied. The minimum dose level (MDL) and limit of detection (LOD), in irradiated and spiked samples, were 0.5 kGy and 5.0 μg L⁻¹, respectively. Furthermore, linear correlation between 2-DCB and 2-TCB contents was demonstrated. Finally, chemometric analysis highlighted the influence of ripening time and dairy technological processes on extraction capability of the two investigated analytes.
Use of ionising radiation for commercial sterilisation to increase the hygienic quality of spices is increasing worldwide. Among several detection methods, Electron Spin Resonance (ESR) spectroscopy is one of the reliable techniques for irradiated foods containing some hard and dried parts. Spices are therefore candidates of such a method and radiation treated spices can be detected. The purpose of the present work was to identify the radiation treatment of spices like cinnamon, cardamom, ginger and rosemary using the sensitive technique of ESR spectroscopy. The spice samples were irradiated to 5, 10, 15 and 20 kilogray (kGy) or unirradiated and the samples were dried in vacuum oven and were placed into quartz tubes for ESR measurement. On measurements, the unirradiated samples were found to show the ESR-signal at g-value of 2.004 that is typical in case of plant foods containing cellulose. Whereas, the irradiated samples showed a formation of a new paramagnetic structure that appeared in the form of a triplet-signal, attributed to radiation-induced cellulose radical. The clear difference between the nature of ESR signals in case of unirradiated and irradiated samples provided the evidence of the radiation treatment of spices samples. It is therefore concluded that radiation treatment of spices can be identified using sensitive ESR spectroscopy during a storage period of three to ten months.
Electron paramagnetic resonance (EPR) spectroscopy can be applied as an effective and non-invasive spectroscopic method for analyzing samples with unpaired electrons. EPR is suitable for the quantification of radical species, assessment of redox chemical reaction mechanisms in foods, evaluation of the antioxidant capacity of food, as well as for the analysis of food quality, stability, and shelf life. It can be employed for evaluating and monitoring the drug release processes, in vitro and in vivo. EPR can be employed for the direct detection of free radical metabolites, and the evaluation of drug release mechanisms from biodegradable polymers; it can be employed for analyzing the drug antioxidant effects. Additionally, spatial resolution can be achieved through EPR-imaging. EPR spectroscopy and imaging have shown diverse applications in food, biomedical and pharmaceutical fields, and also more applications are predictable to emerge in the future. This review highlights recent advances and important challenges related to the application of EPR in food, biomedical and pharmaceutical analysis and assessment.
Electron paramagnetic resonance (EPR) spectroscopy, also known as electron spin resonance (ESR) is a technique that detects paramagnetic atoms and molecules containing unpaired electrons. Unpaired electrons occur in free radicals and many transition metals complexes. It is a highly sensitive, versatile and specific technique that enables static and dynamic studies of materials, chemical samples, and biological systems. EPR's specificity to paramagnetic species makes it valuable to research and development in biology and medicine and physical sciences, as well as pharmaceutical and food industries. EPR has many applications in natural product research. Using EPR it is possible to detect antioxidant capacity to quench free radicals. For example, radical scavenging activity of silymarin and its major flavonolignans components as well as white tea extracts and its major catechin components were measured using this technique. EPR allowed the identification of slow-rate, intermediate-rate and fast-rate antioxidants in differently colored lettuce cultivars. In addition, antioxidant capacity of 21 kinds of fruits including strawberry, mulberry, lemon, and banana was measured using EPR and UV–vis spectroscopy and the two techniques were found highly correlated. EPR spectroscopy was used for studying the antioxidant activity of lemon balm, eyebright, St. John's Wort and sage.
EPR spectroscopy has useful applications in pharmaceutical and food industry involving natural products. Heat, light, oxygen, moisture, sterilization processes, impurities, and excipient interactions are some of the factors that can compromise natural products stability. If natural products are involved in manufacturing of pharmaceuticals, these factors may cause degradation of the active pharmaceutical ingredients, excipients, or formulations resulting in loss of product potency or toxic by-product generation. Degradation processes quite often involve free radicals that are responsible for the majority of the damage that occurs in drug products. For example, oxidative stability of olive oil was studied using EPR and correlated to its content of polyphenols and tocopherols. EPR finds application in detecting free radicals in plants induced by irradiation used for decontamination as alternative to heat and fumigation. The versatility of EPR technique opens future perspectives for more applications in elucidating metabolism of secondary metabolites involving paramagnetic species.
A brief list of the main directions in radiation processes using ionizing radiation in a wide range of doses and energies is given. The necessity of monitoring doses in irradiated objects and diagnosing radiation fields is substantiated. It is noted that in world practice, these problems are solved with the help of dosimetric EPR systems and detectors based on L-α-alanine. Using the example of sterilizing medical devices by radiation from an electron accelerator, a series of experimental results have been obtained that confirm the possibility of using polytetrafluoroethylene as a detector in dosimetric EPR systems for monitoring radiation processes.
A brief list of the main directions in radiation technologies using ionizing radiation in a wide range of doses and energies is given. The necessity of dose control in irradiated objects and diagnostics of radiation fields is proven. It is noted that in world practice these problems are solved using an EPR dosimetry system using detectors based on L-α - alanine. A series of experimental results was obtained, showing the possibility of using Russian EPR / PTFE dosimetry system for routine dose measurements during radiation sterilization of medical equipment.
Oxidation is one of the deterioration reactions of proteins in food, whose importance does not lag behind that of others such as Maillard, lipation or protein‐polyphenol reactions. While research on protein oxidation has led to an accurate perception on the processes and consequences in physiological systems, knowledge on specific implications of protein oxidation in food or the role of “oxidized” dietary protein for the human body is comparatively scarce. Food protein oxidation can occur during the whole processing axis, from primary production to intestinal digestion. The present review wants to summarize the current knowledge and mechanisms of food protein oxidation from a chemical, technological and nutritional‐physiological viewpoint and give a comprehensive classification of the individual reactions. Different analytical approaches will be compared, and the relationship between oxidation of food proteins and oxidative stress in vivo will be critically evaluated.
Oxidation is one of the deterioration reactions of proteins in food, the importance of which is comparable to others such as Maillard, lipation, or protein‐phenol reactions. While research on protein oxidation has led to a precise understanding of the processes and consequences in physiological systems, knowledge about the specific effects of protein oxidation in food or the role of “oxidized” dietary protein for the human body is comparatively scarce. Food protein oxidation can occur during the whole processing axis, from primary production to intestinal digestion. The present review summarizes the current knowledge and mechanisms of food protein oxidation from a chemical, technological, and nutritional–physiological viewpoint and gives a comprehensive classification of the individual reactions. Different analytical approaches are compared, and the relationship between oxidation of food proteins and oxidative stress in vivo is critically evaluated.
The development of reliable methods to distinguish between irradiated and non-irradiated food is essential to address the growing industrial interest in irradiation technology. DNA comet and thermoluminescence (TL) analyses were carried out to investigate radiation-induced markers in gamma-irradiated grapes (0–2 kGy). A DNA comet assay of the seeds and flesh of irradiated samples displayed tailed cells with a dose-dependent increase in tail length. In TL measurements, irradiated samples were characterized by a prominent TL peak at 180 °C with enhanced intensity. The TL ratio (TL1/TL2) enhanced the reliability of the results by confirming successful isolation of minerals. Irradiation was detectable for up to 6 weeks of storage, with overall acceptance qualities confirmed by a sensory evaluation. The results of the study suggest that both detection techniques could be used to identify irradiated grapes and that simultaneous use could provide a clear determination of irradiation status.
The aim of the present study is to prove radiation processing in air dehydrated dates, prunes and figs, as well as to recommend which part of the fruit to sample. The detection method is Electron Paramagnetic Resonance (EPR) spectroscopy. Before irradiation in date stone, prune stone and flesh, and fig seeds EPR spectroscopy was detected a weak singlet line, whereas date flesh and fig flesh are EPR silent. After gamma-irradiation in date stone and flesh, and fig flesh a “sugar-like” EPR spectrum is recorded. In prune stone a typical “cellulose-like” spectrum is detected, whereas in prune flesh and fig stone only singlet line is recorded as before radiation treatment. Of research done it can be seen that the irradiation is proved in a different part of the fruit. European Protocol EN 13708 is applicable to irradiated dried dates and figs, whereas Protocol EN 1787 for dried prunes. © 2016, National Centre for Agrarian Sciences. All rights reserved.
In this study, the impact of gamma (γ) radiation on seeds was investigated in four native alpine species, Campanula barbata L., Cirsium spinosissinum (L.) Scop., Plantago alpina L., and Silene vulgaris (Moench) Garcke. Seeds were γ-irradiated with 100 and 200 Gy total doses delivered at a dose rate of 2.7 Gy min⁻¹. Irradiated and non-irradiated seeds were used immediately, and subsequently 7 and 14 days after drying (15% Relative Humidity, 15°C) to assess their response to standard seed bank processing. Germination rates, seedling length and weight, antioxidant activity and phenolics content were measured, while free radical accumulation profiles were acquired by electron paramagnetic resonance (EPR). Germination was only hampered in irradiated C. barbata seeds. C. barbata and C. spinosissinum seedlings obtained from irradiated seeds suffered a decrease in length and weight, while growth was not affected in P. alpina and S. vulgaris, when compared to non-irradiated control. Although profiles of seed antioxidant activity were not influenced immediately after γ-irradiation, subsequent drying under seed bank standards induced changes in seed antioxidant activity, depending on the species. According to EPR data, C. barbata and C. Spinosissinum seeds revealed high free radical levels in non-irradiated samples, which were further enhanced by γ-irradiation. An opposite behaviour was observed in P. alpina and S. vulgaris. The four alpine species showed different profiles of γ-ray sensitivity. The reported data encourage future research to test inter-specific variability in the plant response to γ-rays based on a multidisciplinary approach which integrates environmental data. Considering that seeds of alpine plants are short-lived in storage, γ-irradiation could emerge as a promissory priming tool for native endangered species.
The γ-radiation induced changes in ground black pepper (Piper nigrum L.), allspice berries (Pimenta officinalis L.), ginger root (Zingiber officinale Rosc.), dried clove buds (Caryophyllus aromaticus L.) and dry oregano leaves (Origanum vulgare L.) exposed to doses from 2.5 to 30 kGy using 60Co source were studied by EPR spectroscopy. Influence of the dose on the character of generated paramagnetic structures, as well as their thermal stability and lifetime were investigated. EPR spectrum of all reference (non-irradiated) samples consists of a broad singlet line with unresolved hyperfine splitting, attributable to Mn(II) ions, upon which an additional narrow EPR signal (g = 2.0022; ΔBpp ∼ 1 mT) is superimposed, assigned to stable semiquinone radicals produced by the oxidation of polyphenolics in plants. The analysis of individual EPR spectra of γ-radiation treated spice showed the formation of new paramagnetic structures of different origin (mostly cellulose and carbohydrate), which exhibited diverse thermal stability and life-time. Ethanolic extracts of reference spice samples showed considerable radical scavenging ability using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical as an oxidant. The influence of γ-radiation dose on the ability of spice extracts to terminate DPPH was also investigated. The results indicated that the antioxidant capacity was only slightly affected by the radiation treatment.
The objective of the present study was to prove the radiation treatment of a set of lyophilized forest fruits (blackberry, blueberry, aronia, strawberry and black elder), irradiated with doses of 2 and 4 kGy by the method of Electronic Paramagnetic Resonance (EPR). A low intensive singlet line was registered for all samples before the irradiation. The results show that after irradiation the intensity of the natural signal is increased, as the so-called "cellulose like" EPR spectrum was registered only for aronia. From the studied lyophilized fruits, according to the protocol for irradiated foods, containing cellulose (EN 1787), and radiation treatment can be proved only for aronia. Protocol EN 13708 for irradiated foods, containing crystalline sugar is not applicable for these samples.
This paper reviewed the status of food irradiation in Asia, the European Union, and the United States in 2010. Our results show that quantities of irradiated foods in Asia, the EU, and the US in 2010 were estimated at 285200, 9300, and 103000 tons, respectively. Compared with 2005, the quantity of irradiated foods was 100000 tons higher in Asia and 10000 tons higher in the US but 6000 tons lower in the EU. Thus, commercial food irradiation has increased significantly in Asia during the 5-year period studied. Phytosanitary irradiation of fruits and agricultural products has recently increased with 6 countries having irradiated 18500 tons in 2010.
The results of electron paramagnetic resonance (EPR) study on commercially available juices from various fruits and different fruit contents: 25%, 40%, 50%, and 100%, homemade juices, nectars and concentrated fruit syrups, before and after gamma-irradiation are reported. In order to remove water from non- and irradiated samples all juices and nectars were filtered; the solid residue was washed with alcohol and dried at room temperature. Only concentrated fruit syrups were dried for 60 min at 40 °C in a standard laboratory oven. All samples under study show a singlet EPR line with g=2.0025 before irradiation with exception of concentrated fruit syrups, which are EPR silent. Irradiation of juice samples gives rise to complex EPR spectra which gradually transferred to “cellulose-like” EPR spectrum from 25% to 100% fruit content. Concentrated fruit syrups show typical “sugar-like“ spectra due to added saccharides. All EPR spectra are characteristic and can prove radiation treatment. The fading kinetics of radiation-induced EPR signals were studied for a period of 60 days after irradiation.
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The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40°C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048±0.0005 before irradiation. Irradiation gives rise to typical “cellulose-like” EPR spectrum featuring one intensive line with g=2.0048±0.0005 and two very weak satellite lines situated 3mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs—Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs.
The shape and time stability of the electron paramagnetic resonance (EPR) spectra of non- and γ-irradiated papaya, melon, cherry and fig samples dehydrated via osmosis are reported. It is shown that non-irradiated samples are generally EPR silent whereas γ-irradiated exhibit “sugar-like” EPR spectra. The recorded EPR spectra are monitored for a period of 7 months after irradiation (stored at low humidity and in the dark). The results suggest longer period of unambiguous identification of the radiation processing of osmose dehydrated fruits. Therefore, the Protocol EN 13708,2001 issued by CEN is fully applicable for the studied fruit samples.
The changes in spice paprika powder induced by ionizing radiation, saturated steam (SS) and their combination were studied as a function of the absorbed radiation dose and the storage time. The SS treatment lead to a decrease in color content (lightening) after 12 weeks of storage, together with the persistence of free radicals and viscosity changes for a longer period. The results suggest that ionizing radiation is a more advantageous method as concerns preservation of the quality of spice paprika.
Laurel leaf (Laurus nobilis L.) samples that originated from Turkey were analyzed by electron spin resonance (ESR) and thermoluminescence (TL) techniques before and after γ-irradiation. Unirradiated (control) laurel leaf samples exhibit a weak ESR singlet centered at g=2.0020. Besides this central signal were two weak satellite signals situated about 3 mT left and right to it in radiation-induced spectra. The dose–response curve of the radiation-induced ESR signal at g=2.0187 (the left satellite signal) was found to be described well by a power function. Variation of the left satellite ESR signal intensity of irradiated samples at room temperature with time in a long term showed that cellulosic free radicals responsible for the ESR spectrum of laurel leaves were not stable but detectable even after 100 days. Annealing studies at four different temperatures were used to determine the kinetic behavior and activation energy of the radiation-induced cellulosic free radicals responsible from the left satellite signal (g=2.0187) in laurel leaves. TL measurements of the polymineral dust isolated from the laurel leaf samples allowed distinguishing between irradiated and unirradiated samples.
Electron spin resonance (ESR) and thermoluminescence (TL) signals induced by gamma irradiation in linden (Tilia vulgaris) were studied for detection and dosimetric purposes. Before irradiation, linden leaf samples exhibit one singlet ESR signal centred at g = 2.0088. Besides this central signal, in spectra of irradiated linden samples, two weak satellite signals situated about 3 mT left (g = 2.0267) and right (g = 1.9883) were observed. Dose-response curves for the left satellite signal and the central single signal were constructed, and it was found that both of these curves can be described best by the combination of two exponential saturation functions. Variable temperature and fading studies at room temperature showed that the radiation-induced radicals in linden leaf samples are very sensitive to temperature. The stabilities of the left satellite (g = 2.0267) and the central single (g = 2.0088) signal at room temperature over a storage period of 126 days turned out to be best described by a sum of two first-order decay functions. The kinetic features of the left satellite signal were studied over the temperature range of 313-373 K. The results indicate that the isothermal decay curves of the left satellite ESR signal also proved to be best fitted by the combination of two first-order decay functions. Fading and annealing studies suggested the existence of two different radiation-induced free radical species. At the same time, Arrhenius plots evidenced two different kinetic regimes with two different activation energies. TL investigation of polyminerals from the linden samples allowed to discriminate clearly between irradiated and unirradiated samples even 75 days after irradiation.
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.
Photostimulated luminescence (PSL), thermo-luminescence (TL), and electron spin resonance (ESR) analyses were performed to identify γ-irradiated (0, 1,2, and 3 kGy) fresh mushrooms (oyster, king oyster, and shiitake mushrooms) during storage at 5 o C. PSL analysis gave negative results [<700 photon counts (PCs)] for the nonirradiated and intermediate (700-5,000 PCs) or positive results (>5,000 PCs) for the irradiated samples. The shape, intensity, and occurrence of TL glow curve in a typical temperature range (150-250 o C) along with TL ratio (TL 1 / TL 2) provided sufficient information to confirm the irradiation history of samples. Storage resulted in a negligible fading effect on PSL and TL characteristics. X-ray diffraction analysis showed the abundance of feldspar and quartz minerals in the separated dust from mushrooms. In detailed ESR analysis employing different sample pre-treatments, all samples were silent for radiation-specific ESR signals giving only a central signal (g=2.005) that showed an increase in intensity upon irradiation.
This study aims primarily to investigate the usage of differences in microwave (MW) saturation behaviour of food samples for identification of radiation treatment. Twenty different samples (dry plant, herbal, spice etc.) which do not have radiation specific satellite ESR signal were especially selected. It is not possible to detect radiation treatment on these samples by European standard (EN 1787, 2000). MW saturation studies were performed on all samples in the range of 0.01-160mW. Our experimental results demonstrate that radiation identification can be possible for ten samples and cannot be possible for the other ten samples by performing the MW saturation studies.
Just with the emergence of the idea to treat food by ionizing radiation, the concerns were voiced whether it would be safe to consume such food. Now, we look back on more than hundred years of research into the 'wholesomeness', a terminology developed during those efforts. This review will cover the many questions which had been raised, explaining the most relevant ones in some detail; it will also give place to the concerns and elucidate their scientific relevance and background. There has never been any other method of food processing studied in such depth and in such detail as food irradiation.
The conclusion based on science is:
Consumption of any food treated at any high dose is safe, as long as the food remains palatable. This conclusion has been adopted by WHO, also by international and national bodies. Finally, this finding has also been adopted by Codex Alimentarius in 2003, the international standard for food. However, this conclusion has not been adopted and included at its full extent in most national regulations.
As the literature about wholesomeness of irradiated food is abundant, this review will use only a few, most relevant references, which will guide the reader to further reading.
It is surprising what all can be achieved by radiation processing of food; this chapter narrates a number of less obvious applications mostly hidden to the consumer. Also the labelling regulations differing world-wide are responsible for leaving the consumer uninformed. Several of the early proposals could not reach technological maturity or are commercially not competitive. Still considerable energy is spent in research for such applications. Other applications are serving a certain niche, companies mostly are reluctant to release reliable information about their activities. Labelling regulation vary world-wide significantly. Hence, the market place does not really give the full picture of irradiated food available to the consumer. Despite those restrictions, this report intends to give a full picture of the actual situation for meat, fish and others and of unique uses.
There is an established framework of international standards for food irradiation covering human health, plant protection, labelling, dose delivery, quality assurance and facility management. Approximately 60 countries permit irradiation of one or more food or food classes. National regulations are briefly reviewed. Decontamination of spices, herbs and condiments remains the single largest application of irradiation. However, in recent years the market for irradiated fresh and processed meat has become firmly established in several countries including China and the USA. At least 10 countries have recently established bi-lateral agreements for trade in irradiated fresh fruits and vegetables using phytosanitary irradiation. Irradiated fresh produce volumes now exceed 20,000 t per year. Rationalization and greater consistency in labelling regulations would be advantageous to the future growth of applications of food irradiation.
It was clear to members of the group that carbon is important in the interpretation of several spectral regions of cosmic dust: the UV region, primarily because of the 2200 Å interstellar band, the 3 to 15 µm IR region, because of various unidentified bands in this region (including those at 3.3, 6.2, 7.7, 8.8 and 11.3 µm), and the far infrared region because of the necessity of fitting emissivity observations in this region. Carbon may also be important in the visible for explaining diffuse interstellar bands (4430 Å, etc.) following tentative suggestions for explanations based on clusters of carbon atoms in linear chains or in poly cyclic carbon molecules. It has became more and more clear, however, that carbon is an extremely complicated and variable material. The first part of this summary expresses our concern for evaluating and describing the nature of carbon used in experiments. Following this, three significant problems are summarized and in the final section a list of recommended work that is needed is given.
The influence of γ-irradiation at doses from 5 kGy to 30 kGy on oregano (Origanum vulgare L.) was studied by the conventional microbiological analysis tests and by the combination of GC-FID; GC-MS; GC-Olfactometry (GC-O); EPR and UV-VIS spectroscopy. Microbiological analysis proved that γ-irradiation at 7.5 kGy was sufficient to achieve the microbiological decontamination of oregano samples, persisting even after 8 months of storage. The study of γ-irradia-tion impact on essential oils' composition and on organoleptic quality changes, evaluated using GC-FID, GC-MS, and GC-O involving the Aroma Extract Dilution Analysis (AEDA) method revealed no changes in the chemical composition and non-considerable changes in the content of volatile oils' compounds at samples γ-irradiated up to 10 kGy. Only non-significant changes of flavours upon the radiation treatment even at dose of 30 kGy were noticed. The analysis of EPR spectra confirmed the presence of two signals in a reference sample, attributed to Mn2+ ions and to stable semiquinone radicals. In addition, the dose-dependent formation of radicals of different origin (mostly cellulose and carbohydrate) showing the diverse thermal stability and life-time was noticed in γ-irradiated samples. UV-VIS experiments confirmed that the antioxidant activity of oregano ethanolic extracts was only slightly affected by the absorption of γ-radiation.
The relationship between electron spin resonance (ESR) signal intensity of irradiated plant materials and sugar content was investigated by spectral analysis using peony roots.
A weak background signal near g=2.005 was observed in the roots. After a 10 kGy irradiation, the ESR line broadened and the intensity increased, and the spectral characteristics were similar to a typical spectrum of irradiated food containing crystalline sugars. The free radical concentration was nearly stable 30 days after irradiation. The spectrum of peony root 30 days after irradiation was simulated using the summation of the intensities of six assumed components: radical signals derived from (a) sucrose, (b) glucose, (c) fructose, (d) cellulose, (e) the background signal near g=2.005 and (f) unidentified component. The simulated spectra using the six components were in agreement with the observed sample spectra. The intensity of sucrose radical signal in irradiated samples increased proportionally up to 20 kGy. In addition, the intensity of sucrose radical signals was strongly correlated with the sucrose contents of the samples. The results showed that the radiation sensitivity of sucrose in peony roots was influenced little by other plant constituents. There was also a good correlation between the total area of the spectra and the sucrose content, because the sucrose content was higher than that of other sugars in the samples. In peony roots, estimation of the absorbed dose from the ESR signal intensity may be possible by a calibration method based on the sucrose content.
Different spices such as turmeric, oregano, and cinnamon were gamma irradiated at 1 and 10 kGy. The electron paramagnetic resonance (EPR) spectra of the nonirradiated samples were characterized by a single central signal (g = 2.006), the intensity of which was significantly enhanced upon irradiation. The EPR spectra of the irradiated spice samples were characterized by an additional triplet signal at g = 2.006 with a hyperfine coupling constant of 3 mT, associated with the cellulose radical. EPR analysis on various sample pretreatments in the irradiated spice samples demonstrated that the spectral features of the cellulose radical varied based on the pretreatment protocol. Alcoholic extraction pretreatment produced considerable improvements of the EPR signals of the irradiated spice samples relative to the conventional oven and freeze-drying techniques. The alcoholic extraction process is therefore proposed as the most suitable sample pretreatment for unambiguous detection of irradiated spices by EPR spectroscopy.
In this work we use paramagnetic defects induced by radiation in the fruit pulp to identify gamma-irradiated kiwi, papaya and tomato. Pulp without seed, peels or stalks are treated by alcoholic extraction in order to remove water, soluble fractions and solid residue. The ESR spectra of pulp samples of irradiated fruit is composed of species A (g = 2.0045) and species C (g = 2.0201 and g = 1.9851), which are also observed in irradiated stalks and skins. In comparison with samples which are not submitted to alcoholic extraction, species C is stable enough to be used as a dose marker. Furthermore, the species C signal can be detected perfectly even in pulp samples irradiated with doses as low as 200 Gy. Irradiation doses of fruit, exposed to 200–900 Gy of a gamma rays, were estimated with an overall uncertainty of 15% using dried pulp samples. These results indicate that radicals induced in pulp have potential to be used in the identification and absorbed dose determination of irradiated fruit.
The use of electron paramagnetic resonance spectroscopy to accurately distinguish irradiated from unirradiated cardamom and cloves and assesses the absorbed dose to radiation processed cardamom and cloves are examined. The results were successful for identifying both irradiated and unirradiated cardamom and cloves. Additive reirradiation of cardamom and cloves produces reproducible dose–response functions, which can be used to assess the initial dose by back-extrapolation. Third degree polynomial function was used to fit the EPR signal/dose curves. It was found that this 3rd degree polynomial function provides satisfactory results without correction of decay for free radicals. The stability of the radiation induced EPR signal of irradiated cardamom and cloves were studied over a storage period of almost 8 months.
The calculated G-value (The number of radicals per 100 eV of absorbed energy) for cardamom and cloves was found 0.07±0.01 and 0.055±0.01, respectively.
Using electron paramagnetic resonance (EPR) spectroscopy, we revealed the relaxation behaviors of free radicals in γ-irradiated black pepper. Upon γ-irradiation, typical doublet peaks were detected. Relaxation times (T 1 and T 2) were observed using pulsed EPR. We found that T 1 and T 2 values varied with the γ-irradiation dose levels and these values showed a dependence on the dose level of the γ-irradiation treatment.
2) were observed using pulsed EPR. We found that T
1 and T
2 values varied with the γ-irradiation dose levels and these values showed a dependence on the dose level of the γ-irradiation treatment.
Food irradiation can be used to increase the microbiological safety and to extend the shelf life of foods. European legislation states that any food or food ingredients must be labelled and every year each Member State, particularly Italy, has to carry out checks at marketing stage. This work reports on the results of analytical controls on 451 foodstuff samples over the period 2006–2011 performed by an Italian accredited laboratory using 4 different screening and confirmatory techniques: PSL, DNA Comet Assay, TL and ESR. A total of 18 samples were found non-compliant: 6 frog legs, 3 clams, 3 cuttlefish, 1 octopus and 1 shrimps from Vietnam; 3 squids, 1 white pepper and 1 chilli tofu from China. Non-compliances are due to both incorrect labelling and irradiation in not approved facilities in extra European/third countries. Check results also showed that among screening methods PSL is the most accurate, simple and practical standard to analyse most of samples (spices, herbs, supplements, mollusks, crustaceans and vegetables) with a low false positive classification (11%) whereas DNA Comet Assay revealed the highest percentage of false positive cases (26%). ESR is the suitable confirmatory method to detect dried fruits and foodstuffs (meat and fish product) containing bone, while TL is the best confirmatory method to detect herbs, spices and supplements, cephalopods, mollusks and crustaceans, besides fresh fruits and vegetables. In conclusion, by comparison with European data, this study suggests more checks on meat products (frog and poultry meats), fish products (cephalopods, mussels and crustacean) spices and supplements especially at import stage from countries where non approved irradiation facilities are operating (e.g. Vietnam and China).
The electron spin resonance spectrum of achenes of refrigerated strawberries allows one to assert whether or not the fruit has been irradiated under commercial conditions required to inactivate the moulds responsible for food loss.
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.
Seeds of fig produced in Turkey were studied by electron spin resonance (ESR) technique for detection purposes. Unirradiated fig seeds (control) exhibited a weak ESR singlet at g=2.0052±0.0003 (native signal). Irradiation induced at least one additional intense singlet overlapping to the control signal and caused a significant increase in signal intensity without any changes in spectral patterns. Variation of ESR signal intensity of irradiated samples at room temperature with time in a long-term showed that free radicals responsible from the ESR spectrum of fig seeds were not stable but detectable after 80days. Annealing studies at five different temperatures were used to determine the kinetic behaviour and activation energy of the radiation-induced radicals in fig seeds. A study on microwave saturation characteristics and thermal behaviour of the ESR singlet (g=2.0052) in irradiated and unirradiated fig seed samples was also carried out by using ESR technique. These preliminary results indicate that microwave saturation characteristics of the ESR signal at room and low temperatures may be useful method to distinguish irradiated fig seeds from unirradiated ones.
Feature changes in the ESR spectrum and the relationship between ESR intensity and irradiation dose ranging between 0 and
15.0 kGy were studied to detect irradiated cumin and white pepper by ESR spectroscopy. The absorbed irradiation doses of two
samples were assessed using the dose-additive method. The ESR signal intensities of irradiated cumin and white pepper increased
with increasing absorbed radiation dose. Even after 220 days, the ESR method could still be used to identify whether or not
cumin and white pepper had been irradiated. The dose-additive method can be used to reliably evaluate the absorbed doses of
cumin and white pepper. The 3rd polynomial function can be used to fit the data. Long-term decay of the radiation-induced
radical has a marked influence on dose assessment and leads to an underestimation of the dose.
The hydrocarbon method for the detection of irradiated foods is now recognized as the international technique. This method is based on radiolysis of fatty acids in food to give hydrocarbons. In order to expand this technique's application, ten foods (butter, cheese, chicken, pork, beef, tuna, dry shrimp, avocado, papaya, and mango) were irradiated in the range from 0.5 to 10 kGy and the hydrocarbons in them were detected. Recoveries of the hydrocarbons from most foods were acceptable (38-128%). Some hydrocarbons were found in non-irradiated foods, particularly, in butter, cheese, tuna, and shrimp. Seven irradiated foods, butter, cheese, chicken, beef, pork, tuna, dry shrimp, and avocado were detectable at their practical doses by measuring the appropriate marker hydrocarbons. In most case, marker hydrocarbon will be 1,7-hexadecadiene. However, the marker hydrocarbons produced only in irradiated foods varied from food to food; therefore, it is necessary to check a specific irradiated food for marker hydrocarbons. On the other hand, two irradiated foods (papaya and mango which were irradiated at their practical doses) were difficult to distinguish from non-irradiated foods using this method.
Non irradiated and γ-irradiated dry herbs savoury (Savoury), wild thyme (Thymus serpollorium) and marjoram (Origanum) with absorbed dose of 8 kGy have been investigated by the methods of elecrtron paramagnetic resonance (EPR) and thermoluminescence (TL). Non-irradiated herbs exhibit only one weak siglet EPR signal whereas in irradiated samples its intensity increase and in addition two satelite lines are recorded. This triplet EPR spectrum is attributed to cellulose free radical generated by irradiation. It has been found that upon keeping the samples under the normal stock conditions the life-time of the cellulose free radical in the examined samples is ∼60–80 days. Thus the conclusion has been made that the presence of the EPR signal of cellulose free radical is unambiguous indication that the sample under study has been irradiated but its absence can not be considered as the opposite evidence. In the case when EPR signal was absent the method of TL has been used to give the final decision about the previous radiation treatment of the sample.
The ESR spectra of the seeds, skins and stalks of unirradiated and γ-irradiated Cape black grapes have been obtained. In the spectra of all parts of the grape a single line (g ca. 2.004) is observed both before and after irradiation. New spectral features are observed after irradiation with doses of between 2 and 10 kGy. Some of these features decline in intensity over a period of several days. However, in the case of stalks, new spectral features are readily observed over the shelf-life of the fruit and in samples irradiated to a dose of only 2kGy.
The radiation-induced EPR spectra in some medical herbs are reported. The samples studied are: (i) leaves of nettle, common balm, peppermint and thyme; (ii) stalks of common balm, thyme, milfoil, yarrow and marigold; (iii) blossoms of yarrow and marigold; (iv) blossoms and leaves of hawthorn and tutsan; and (v) roots of common valerian, nettle, elecampane (black and white), restharrows and carlina. Before irradiation all samples exhibit one weak anisotropic singlet EPR line with effective g-value of 2.0050±0.0002. The radiation-induced spectra fall into three groups. EPR spectra of irradiated blossoms of yarrow and marigold, stalks of common balm, thyme, tutsan and yarrow as well as roots of common valerian, nettle and elecampane (black and white) show “cellulose-like” EPR spectrum typical for irradiated plants. It is characterized by one intense central line with g=2.0050±0.0005 and two weak satellite lines situated ca. 30G left and right to it. EPR spectra of gamma-irradiated restharrows and carlina are complex. They may be represented by one triplet corresponding to the “cellulose-like” EPR spectrum, one relatively intense singlet, situated in the center of the spectrum, and five weak additional satellite lines left and right to the center. The last spectrum was assigned as “carbohydrate-like” type. Only one intense EPR singlet with g=2.0048±0.0005 was recorded after irradiation of leaves of nettle and common balm. The lifetime of the radiation-induced EPR spectra was followed for a period of 3 months.
Food spoilage is caused by infestation by insects, contamination by bacteria and fungi and by deterioration by enzymes. In the third world, it has been estimated that 25% of agricultural products are lost before they reach the market. One way to decrease such losses is by treatment with ionising radiation and maximum permitted doses have been established for treatment of a wide variety of foods. For dates this dose is 2.0kGy. Detection of irradiated foods is now essential and here we have used ESR to detect and estimate the dose received by a single date. The ESR spectrum of unirradiated date stone contains a single line g=2.0045 (signal A). Irradiation up to 2.0kGy induces radical formation with g=1.9895, g=2.0159 (signal C) and g=1.9984 (signal B) high field. The lines with g=1.9895 and 2.0159 are readily detected and stable at room temperature for at least 27 months for samples irradiated up to this dose. The yield of the radicals resulting in these lines increase linearly up to a dose of 5.0kGy as is evidenced by the linear increase in their intensity. In blind trials of 21 unirradiated and irradiated dates we are able to identify with 100% accuracy an irradiated sample and to estimate the dose to which the sample was irradiated to within ∼0.5kGy.
The use of electron spin resonance (ESR) spectroscopy to accurately distinguish irradiated from unirradiated sage tea was examined. Before irradiation, sage tea samples exhibit one asymmetric singlet ESR signal centered at g=2.0037. Besides this central signal, two weak satellite signals situated about 3mT left and right to it in radiation-induced spectra. Irradiation with increasing doses caused a significant increase in radiation-induced ESR signal intensity at g=2.0265 (the left satellite signal) and this increase was found to be explained by a polynomial varying function. The stability of that radiation-induced ESR signal at room temperature was studied over a storage period of 9 months. Also, the kinetic of signal at g=2.0265 was studied in detail over a temperature range 313–353K by annealing samples at different temperatures for various times.
In the present work, the effects of storage time and temperature on the resonance signals of unirradiated and irradiated dry pea (Pisum sativum L.) were investigated using electron spin resonance (ESR) spectroscopy. As other legumes, unirradiated pea contains Mn2+ binded proteins and very small amount natural free radicals. They give rise to an ESR spectrum consisting of an equally spaced sextet and a singlet resonance line, respectively, both appearing at g=2.0050±0.0007. Irradiation of pea by gamma radiation did not produce any pattern changes in the ESR spectrum of pea except a significant change in the intensity of the singlet resonance line which increased exponentially with absorbed dose in the studied dose range (1.25–15.0 kGy). Cooling the irradiated samples down to room temperature caused a reversible increase in Mn2+ and a reversible decrease in free radical signal intensities. However, heating the sample above room temperature created irreversible decreases in the intensities of both species. At room temperature, the free radical signal decayed very fast, but the signal due to Mn2+ ion did not exhibit any intensity changes over the storage period of 75 days. While, annealing of irradiated samples at high temperatures (308–373 K) produced continuous decrease in the signal intensity of Mn2+, it caused a decrease at the beginning and then an increase in the free radical signal intensity. Arrhenius plot constructed using rate constants determined from the variations of the signal intensities at high temperatures was used to calculate activation energies related with oxidation of Mn2+ and free radical species responsible from singlet resonance line.
Control of irradiated food on the market is a requirement of EU regulations. In order to improve checks of irradiated food in Greece, electron spin resonance (ESR) and photostimulated luminescence (PSL) were tested to detect electron beam radiation treatment of representative samples, namely fish (herring) and aromatic plant (oregano). The absorbed irradiation doses for both food samples were 1, 4 and 10 kGy. The effect of thermal treatment and storage time of fish samples on the sensitivity of ESR method as well as the effect of light exposure (after irradiation treatment) and storage time of oregano samples on the sensitivity of PSL method was studied. In addition, the suitability of both methods for two food samples was studied. For fish samples, the detection of irradiation treatment was based on ESR or PSL signal of fish bones. The results showed that PSL is a sensitive detection method for irradiated oregano samples allowing verification of irradiation treatment for all absorbed doses but this is not a sensitive detection method for irradiated herring containing bones. In contrast, ESR allowed verification of the irradiation treatment of fish bone samples but this is not a sensitive method for irradiated oregano samples. Daylight exposure of oregano samples (10 klux, 9 h) produced a strong effect on the PSL signal of all irradiated samples decreasing or disappearing the irradiation signal, while the thermal treatment (100 ± 1 C, 1 h) of fish bones was produced a clear decreasing effect on the ESR signal of irradiated samples mainly for the higher dose of 10 kGy. The storage time strongly affected the PSL signal intensity of oregano samples as well as the ESR signal intensity of herring bone samples but the samples could be correctly identified as irradiated after a storage time of seven months.
Radiation-induced free radicals and luminescence properties were investigated in gamma-irradiated (0-3 kGy) pomegranate (Punica granatum L.) fruits. Photostimulated luminescence (PSL) analysis showed limited applicability and only 3 kGy-irradiated pomegranates showed the positive PSL values (>5,000 PCs). Thermoluminescence (TL) glow curve features, such as intensity and the presence of maximum glow peak in radiation-specific temperature range (150-250oC) provided the definite prove of irradiation, where the TL ratios (TL1/TL2) also confirmed the reliability of TL results. SEM-EDX analysis of the separated minerals showed that feldspar and quartz minerals were responsible for the luminescence properties. Radiation-induced cellulose radicals were detected in the seeds and rind parts by ESR analysis. The ESR results were better in freeze-dried samples than in alcoholic-extracted ones. A positive correlation was found between the ESR and TL signals intensity and irradiation doses; however the most promising detectionability of the irradiation status was possible through the TL analysis.
The suitability of the EPR spectroscopy for detection of γ-irradiation in five species of dried mushroom, currently used in gastronomy: yellow morel—Morchella esculenta, (L.) Pers. (Phylum Ascomycota), button mushroom—Agaricus bisporus (J.E.Lange), Agaricus haemorrhoidarius Fr., golden chantarelle—Cantharellus cibarius Fr., as well as oyster mushroom—Pleurotus ostreatus (Jacq. ex Fr.) (Phylum Basidiomycota) is presented and discussed. Although after irradiation at doses up to 11 kGy, all specimens presented well defined EPR spectra, only A. bisporus EPR signal was enough stable to make detection possible after 18 months.
The 9.50 GHz electron paramagnetic resonance (EPR) spectra of unirradiated and 60Co γ-ray irradiated cardamom (Elettaria cardamomum L. Maton, Zingiberaceae), ginger ((Zingiber officinale Rosc., Zingiberaceae), and saffron (Crocus sativus L., Iridaceae) have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones. After γ-ray irradiation at an absorbed dose of up to 11.3 kGy, the presence of EPR spectra whose amplitude increase monotonously with the absorbed dose has been noticed with all spices. A 100 °C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that compose initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after 83 days storage at room temperature but after 340 days storage at ambient conditions only irradiated ginger displays a weak signal that differs from those of unirradiated sample. All these factors could be taken into account in establishing at which extent the EPR is suitable to evidence any irradiation treatment applied to these spices.
Gamma-irradiated (0, 1, 5 and 10 kGy) spaghetti sauce samples were identified using photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR) techniques. PSL technique was used as a screening method for irradiated sauce samples, where the improved results of PSL method were observed for the freeze-dried and alcoholic-extracted samples. TL technique, through the density separation step of silicate minerals from irradiated samples, gave specific shape, intensity and occurrence of TL glow curve in a typical temperature range as well as TL ratio (TL 1/TL 2) to identify the irradiation treatment. The ESR method employed for the freeze-dried samples, showed radiation-specific cellulose signals for 5 and 10 kGy-treated samples, and the results were comparable with oven-dried samples. In general, TL technique was found the most sensitive and reliable for the identification of irradiated spaghetti sauces.
The safety of food irradiation is well documented; however, this technique lacks international consensus for general applicability. Validated identification methods have prime importance for the application of different regulations regarding the international trade of irradiated food. This study comprehensively investigated the potential of different available techniques for the identification of irradiated sauce samples. Liquid samples were treated with different modified methods to find the improved identification results. The presented results may be useful for different regulatory authorities to identify or monitor irradiated spaghetti sauces.
Characteristics of free radical components of irradiated black pepper fruit (skin) and the pepper seed (core) were analyzed using electron spin resonance. A weak signal near g=2.005 was observed in black pepper before irradiation. Complex spectra near g=2.005 with three lines (the skin) or seven lines (the core) were observed in irradiated black pepper (both end line width; ca. 6.8 mT). The spectral intensities decreased considerably at 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of the content and the stability of radical components derived from plant constituents, including fiber, starch, polyphenol, mono- and disaccharide, were in good agreement with the observed spectra. Analysis showed that the signal intensities derived from fiber in the skin for an absorbed dose were higher, and the rates of decrease were lower, than that in the core. In particular, the cellulose radical component in the skin was highly stable.Highlights► We identified the radical components in irradiated black pepper skin and core. ► The ESR spectra near g=2.005 with 3–7 lines were emerged after irradiation. ► Spectra simulated basing on the content and the stability of radical from the plant constituents. ► Cellulose radical component in black pepper skin was highly stable. ► Single signal near g=2.005 was the most stable in black pepper core.