Low-dose Electron Beam Irradiation Research Articles

Effect of low‐dose high‐energy electron beam irradiation on postharvest storage quality of Actinidia arguta

To study the effect of low-dose electron beam irradiation treatment on the postharvest storage quality of Actinidia arguta. The kiwifruit was irradiated with 300, 400, and 500 Gy electron beams, respectively, stored at 0–1°C with 90%–95% RH. The physical and chemical indexes, physiological indexes, and resistance enzyme activities of the fruits were determined. The results showed that 400 Gy electron beam irradiation (EBI) effectively inhibited the increase of weight loss, total soluble solid (TSS) content, respiration rate, malondialdehyde (MDA) accumulation, and the ethylene production, slowed down the moisture and titratable acid (TA) content loss, while significantly increased the peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities. Compared with the untreated fruits, 400 Gy EBI treatment prolonged the shelf life by 20 days. The overall results indicated that as a green postharvest treatment technology, EBI could effectively delay the senescence process, maintain storage quality, and extend the shelf life of the kiwifruit. Practical applications In recent years, electron beam irradiation (EBI) technology has been widely employed for fruit and vegetable storage and processing due to its advantages of high energy utilization, low cost, easy control, safety, and pollution-free. Kiwifruit, a typical climacteric fruit, is prone to dehydration shrinkage, and rot, significantly reducing its edible quality and commercial value. Thus, choosing an appropriate storage and preservation technology is of great significance for the postharvest storage of kiwifruit. The present study results elucidated that 400 Gy dose EBI treatment had a positive effect on inhibiting weight loss of kiwifruit during storage, improving the activities of PAL and POD resistant enzymes, and reducing MDA accumulation. Therefore, the EBI treatment could be a potential green physical preservation technology for kiwifruit post-harvest treatment to maintain fruit storage quality and extend shelf life.

Efficient sensitizer-supported electron beam irradiation induced crosslinking of polyvinylidene fluoride for shape memory applications

Polyvinylidene fluoride (PVDF) preferentially crosslinks upon exposure to ionizing electron beam irradiation, leading to substantial changes in its physicomechanical and thermophysical properties. However, low dose electron beam irradiation produces inefficient crosslinking in pure PVDF while high dose irradiation tends to induce the concomitant process of transverse bond degradation. This has been addressed by incorporating a sensitizer into PVDF to increase crosslinking efficiency under low dose irradiation. However, conventional sensitizers typically suffer from self-polymerization and the release of toxic volatile gases at high temperature, which diminishes the crosslinking efficiency and is toxic. This issue is addressed here via a series of well-designed bismaleimide (BMI) sensitizers and incorporating these into PVDF films for facilitating chemical crosslinking reactions under low electron beam irradiation doses. Analysis indicates that the sensitizing action of the proposed BMI sensitizers may be due to the formation of transverse bonds between vinylene groups and PVDF chains. Versus conventional triallyl isocyanurate and trimethylolpropane triacrylate sensitizers, the proposed BMI sensitizers facilitate high radiation crosslinking efficiency and exhibit good compatibility. Accordingly, the proposed sensitizers leading to irradiated PVDF films with outstanding thermomechanical performance and shape memory functionality.

Influence of Electron Beam Irradiation on the Moisture and Properties of Freshly Harvested and Sun-Dried Rice.

Moisture content is an important factor that affects rice storage. Rice with high moisture (HM) content has superior taste but is difficult to store. In this study, low-dose electron beam irradiation (EBI) was used to study water distribution in newly harvested HM (15.03%) rice and dried rice (11.97%) via low-field nuclear magnetic resonance (LF-NMR). The gelatinization, texture and rheological properties of rice and the thermal and digestion properties of rice starch were determined. Results showed that low-dose EBI could change water distribution in rice mainly by affecting free water under low-moisture (LM) conditions and free water and bound water under HM conditions. HM rice showed smooth changes in gelatinization and rheological properties and softened textural properties. The swelling power and solubility index indicated that irradiation promoted the depolymerization of starch chains. Overall, low-dose EBI had little effect on the properties of rice. HM rice showed superior quality and taste, whereas LM rice exhibited superior nutritional quality. This work attempted to optimize the outcome of the EBI treatment of rice for storage purposes by analyzing its effects. It demonstrated that low-dose EBI was more effective and environmentally friendly than other techniques.

Low-Dose Electron-Beam Irradiation for the Improvement of Biofilm Formation by Probiotic Lactobacilli.

The effects of 50-150 gray electron-beam irradiation on the biofilm-formation ability and cell surface hydrophobicity of the commercial strain, Lactobacillus acidophilus DDS®-1, from Lacto-G (a marketed synbiotic formulation) and the putative probiotic, L. rhamnosus Vahe, were evaluated. No significant changes in cell surface hydrophobicity were found after irradiation, while increases in biofilm-formation abilities were documented for both investigated microorganisms 0.22 ± 0.03 vs. 0.149 ± 0.02 (L. rhamnosus Vahe, 150Gy) and 0.218 ± 0.021 vs. 0.17 ± 0.012 (L. acidophilus DDS®-1, 150Gy). Given this, the use of electron-beam irradiation (50-100Gy) for the treatment of L. rhamnosus Vahe and L. acidophilus DDS®-1 cells may be considered in product sterilization, quality improvement, and packaging practices.

Electron beam irradiation effect on critical heat flux in downward-facing flow boiling

In previous research on nuclear reactors, the effect of irradiation on heat transfer has rarely been studied. We investigated the electron beam irradiation effect on downward-facing flow boiling heat transfer and critical heat flux. All the critical heat flux values in flow boiling decreased after irradiation, particularly at low doses, whereas heat transfer coefficient almost remained the same. Low dose electron beam irradiation substantially increased the nucleation sites on the heated copper surface, and the critical heat flux was inversely related to the nucleation site density in downward-facing flow boiling.

Effect of low dose electron beam irradiation on the alteration layer formed during nuclear glass leaching

This investigation concerns borosilicate glass leaching mechanisms and the evolution of alteration layer under electron beam irradiation. A simple glass doped with rare earth elements was selected in order to access mechanistic and structural information and better evaluate the effects of irradiation. It was fully leached in initially pure water at 90 °C and at high glass surface area to solution volume ratio (S/V = 20 000 m−1) in static conditions. Under these conditions, the system quickly reaches the residual alteration rate regime. A small particle size fraction (2–5 μm) was sampled in order to obtain a fairly homogeneous altered material enabling the use of bulk characterization methods. External irradiations with 10 MeV electrons up to a dose of 10 MGy were performed either before or after leaching, to investigate respectively the effect of initial glass irradiation on its alteration behavior and the irradiation stability of the alteration layer. Glass dissolution rate was analyzed by regular leachate samplings and the alteration layer structure was characterized by Raman, luminescence (continuous or time-resolved), and 29Si MAS NMR and EPR spectroscopy.It was shown that the small initial glass evolutions under irradiation did not induce any modification of the leaching kinetic nor of the structure of the alteration layer. The alteration process seemed to “smooth over” the created defects. Otherwise, the alteration layer and initial glass appeared to have different behaviors under irradiation. No Eu3+ reduction was detected in the alteration layer after irradiation and the defect creation efficiency was much lower than for initial glass. This can possibly be explained by the protective role of pore water contained in the altered material (∼20%). Moreover, a slight depolymerization of the silicon network of the altered glass under irradiation with electrons was evidenced, whereas in the initial glass it typically repolymerizes.

Short communication: Survival of Mycobacterium avium ssp. paratuberculosis in tissues of cows following low-dose exposure to electron beam irradiation

This investigation was designed to determine the effects of low-dose electron beam irradiation on the survival of Mycobacterium avium ssp. paratuberculosis in tissue samples collected at necropsy from clinically affected cows. Mycobacterium avium ssp. paratuberculosis was isolated from the ileum and ileocecal valve of one cow and from the ileum of another cow irradiated at 4.0 kGy, but was not isolated from the ileum, ileocecal valve, or mesenteric lymph node of 11 other cows irradiated at 4 kGy.

The Use of Low-Dose Electron-Beam Irradiation and Storage Conditions for Sprout Control and their Effects on Xanthophylls, Antioxidant Capacity, and Phenolics in the Potato Cultivar Atlantic

Low-dose electron-beam (e-beam) irradiation and storage conditions were evaluated for effectiveness in sprout control and their influence on health-promoting compounds in the potato cultivar Atlantic. Tubers were subjected to zero and 200 Gy and stored at either 4 °C or ambient temperature for 0, 10, 20, 75, and 110 days before evaluation. Xanthophyll content (Xan), antioxidant capacity (AOC), and phenolic content (PC) were quantified by spectrophotometric absorbance; xanthophyll and phenolic compounds were quantified with HPLC-DAD analysis. Tubers held at ambient conditions during storage lost weight and were visibly dehydrated. Tubers exposed to irradiation did not sprout; non-irradiated tubers sprouted, regardless of storage temperature. The exterior layer of tubers had greater total Xan, AOC, and PC than the interior layer, regardless of treatment. Storage time was the most influential factor, affecting Xan, AOC, and PC content. AOC, PC, and chlorogenic acid content increased within the first 10 days of storage, then declined with extended storage. Initially, the AOC and PC increased in irradiated tubers when compared to non-irradiated samples; however, little to no differences were observed once tubers were held in storage. Some exterior layer samples experienced an increase in Xan and PC during the later stages of storage and was believed to be associated with a concentration effect due to dehydration. E-beam irradiation inhibited sprouting during storage and prominent potato health promoting compounds were retained.

Radiation sensitivity of foodborne pathogens in meat byproducts with different packaging

Abstract The aim of this study was to determine radiation sensitivity of Escherichia coli O157:H7 and Listeria monocytogenes in edible meat byproducts. Seven beef byproducts (heart, liver, lung, lumen, omasum, large intestine, and small intestine) and four pork byproducts (heart, large intestine, liver, and small intestine) were used. Electron beam irradiation significantly reduced the numbers of pathogenic microorganisms in meat byproducts and no viable cells were detected in both aerobically- and vacuum-packaged samples irradiated at 4 kGy. Meat byproducts packed under vacuum had higher D10 value than the ones packed aerobically. No significant difference was observed between the D10 values of E. coli O157:H7 and L. monocytogenes inoculated in either aerobically or vacuum packaged samples. These results suggest that low-dose electron beam irradiation can significantly decrease microbial numbers and reduce the risk of meat byproduct contamination by the foodborne pathogens.

저선량 전자선 조사 수입 오렌지의 저온 저장 중 품질 특성

This study investigated the effects of low-dose electron beam irradiation treatment on the physicochemical and sensorial properties of imported navel oranges during storage at 20°C for 12 days. The samples were irradiated at doses of 0.2, 0.4, 0.6, 0.8, and 1.0 kGy, after which changes in color value, hardness, Brix/acid ratio, total sugar contents, reducing sugar contents, vitamin C contents, and sensory evaluation were investigated. There were no significant differences between non-irradiated and irradiated samples in terms of color value, Brix/acid ratio, total sugar contents, total reducing sugar contents, and vitamin C contents. Hardness of irradiated samples significantly decreased in the early storage period in an irradiation dose-independent manner, and the difference between non-irradiated and irradiated samples decreased again at the end of storage. For the sensory evaluation, there was no significant difference between non-irradiated and irradiated samples up to 0.6 kGy, and all sensory item scores decreased at the end of the storage period regardless of irradiation. These results suggest that electron beam irradiation below 0.6 kGy does not affect physicochemical and sensory properties during storage at 20°C. Thus, electron beam irradiation up to 0.6 kGy applied to imported navel oranges is the optimum dose for minimizing quality changes and disinfestation treatment.

Effects of electron-beam irradiation on blueberries inoculated with Escherichia coli and their nutritional quality and shelf life

Fresh blueberries have become a popular new functional food because of their remarkably high levels of antioxidant phytonutrients and health benefits. However, the potential prevalence of human pathogens on blueberries has become an increased concern because they are consumed fresh. Procedures effective in decontamination and extending shelf life without affecting fruit quality are needed. Electron-beam irradiation was applied to fresh blueberries at the doses ranging from 0.5 to 3.0kGy and its effectiveness for inactivating Escherichia coli (E. coli) K-12 and extending shelf life were investigated. The decimal reduction dose, D10 values, of E. coli in cultural medium and blueberries were 0.43±0.01kGy and 0.37±0.015kGy, respectively. Irradiation reduced bacteria inoculated on blueberries from 7.7×108CFU/g to 6CFU/g at 3.13kGy and decreased the decaying of blueberries stored at 4°C up to 72% and at room temperature up to 70% at this dose. No significant effect on the total monomeric anthocyanins, antioxidant activity, and l-ascorbic acid content of blueberries was observed from irradiation at doses ≤3kGy. However, significant decreases in the antioxidant activity and l-ascorbic acid content were found in both control and irradiated blueberries after storage at 4°C for 7 and 15 d. Information obtained in this study indicates that low dose electron-beam irradiation is effective in reducing E. coli and extending shelf life while maintaining the antioxidant properties of blueberries.

Improving the Microbiological Quality and Safety of Fresh-Cut Tomatoes by Low-Dose Electron Beam Irradiation

The effect of electron beam irradiation on microbiological quality and safety of fresh-cut tomatoes was studied. Fresh tomatoes were obtained from a local supplier and then cut into cubes that were separated from the stem scars. Both cubes and stem scars were inoculated with a rifampin-resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups, and treated by electron beam irradiation at 0.0 (control), 0.7, or 0.95 kGy. The effect of electron beam irradiation on Salmonella, lactic acid bacteria, yeast, and mold counts and pH of tomato cubes and stem scars was determined over a 15-day storage period at 4°C. Results indicated that although irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the reduction of microbial populations between treatments of 0.7 and 0.95 kGy. Irradiation at either dose resulted in a significant reduction in Salmonella when compared with the control (P < 0.05). Lactic acid bacteria, yeasts, and molds were more resistant to irradiation than were Salmonella. No differences were detected between the two Salmonella serotypes in response to irradiation treatment. These results indicate that irradiation at doses of at least 0.7 kGy can be used for pathogen reduction in fresh-cut tomatoes. If the use of doses greater than 1 kGy were approved, this technology might be very effective for use in fresh-cut tomatoes to eliminate significant populations of pathogens and to ensure the microbial quality of the product.

Effects of Low‐dose Electron Beam Irradiation on Respiration, Microbiology, Texture, Color, and Sensory Characteristics of Fresh‐cut Cantaloupe Stored in Modified‐atmosphere Packages

ABSTRACTFresh‐cut cantaloupe was placed in modified‐atmosphere packages (4% oxygen, 10% carbon dioxide) and irradiated at 0 (control), 0.5, and 1.0 kGy. Irradiated samples had a lower and more stable rate of respiration than non‐irradiated samples over about 20 d. Total plate counts were higher (P &lt; 0.05) in non‐irradiated control samples through day 11 (Trial 1) and for all dates tested (Trial 2). Color and texture remained stable for the duration of each study as measured by instruments and trained sensory panels. Sensory evaluation rated the 1.0‐kGy sample highest in “sweetness” and “cantaloupe flavor intensity” and lowest in “off‐flavor” after 17 (±3) d of storage. Low‐dose electron beam irradiation of fresh‐cut cantaloupe with modified‐atmosphere packaging offers promise as a method of extending shelf life.

Nano-Graphitization in Amorphous Carbon Films via Electron Beam Irradiation and the Iron Implantation

ABSTRACTNano-graphitization from amorphous carbon state is assisted by the electron beam irradiation. An inter-columnar region in the amorphous carbon films with low atomic and electron densities is controlled to have a graphitic structure with relatively low dose electron beam irradiation. This amorphous carbon ? beam interaction generates a new type of carbon hybrids where amorphous carbon phase columns are sustained by the graphitic inter-columnar network. This hybrid film has an exotic mechanical and tribologic response: extraordinary reversible deformability up to 8 – 10 % normal strain, high wearing resistance and low friction at high normal pressure. A combination of iron implantation with this electron irradiation provides us the other nano-graphitization process. An amorphous carbon film including the implanted iron atoms is chemically modified to have a columnar graphitic structure by the electron beam irradiation. In this post-implantation electron beam irradiation, the basic graphitic units with 1-2 nm in size are controlled to align vertically along the film thickness. This type of nano-graphitization has a strong dependency on the iron doses before electron beam irradiation. The above two types of nano-graphitization provides us a new tool to explore the functionalized structural thin films in application.

Effects of Low-dose Electron Beam Irradiation on Respiration, Microbiology, Color, and Texture of Fresh-cut Cantaloupe

Cantaloupes (Cucumis melo) in three separate trials were cut into 1-inch cubes and irradiated at 0, 0.25, 0.5, 0.75, 1.0, 1.25, or 1.5 kGy; 0, 0.1, 0.2, 0.3, 0.4, 0.5, or 0.7 kGy; and 0, 0.3, 0.6, or 0.9 kGy, respectively. They were then stored in air at 3 °C for up to 20 days, and respiration rate, measured as carbon dioxide (CO2) production, microbiological counts [total plate count (TPC) and yeast and molds], texture, and color were measured during storage. Respiration rates were initially higher in irradiated cantaloupe. After 8 days, respiration was similar between irradiated and control fruit. Irradiation moderated increases in respiration in a dose-dependent manner. Highest irradiation doses resulted in initial TPC reductions of 1.5 log compared to the non-irradiated controls, and also prevented the 2.5 to 3 log TPC increases seen in controls after 10 to 11 days of storage. Texture differed on day 1, when controls were most firm, but irradiation maintained greater firmness than controls after day 7. Irradiation of fresh-cut cantaloupe has potential for shelf life extension and for integration with modified atmosphere packaging systems.

Quality of packaged romaine lettuce hearts exposed to low-dose electron beam irradiation

We investigated the effects of low-dose electron beam irradiation (1.0, 1.5 and 3.2 kGy) on the quality of commercially prepackaged fresh romaine lettuce hearts. The impact of the irradiation treatment on the functionality of the package was also evaluated. Irradiated samples showed slight changes in color, but these changes were not significantly different ( P >0.05) from the nonirradiated (control) samples. Sample firmness decreased by 49.58% (leaves) and 29.13% (ribs), as the dose level increased. Sensory attributes such as overall quality, color, sogginess, and off-flavor were found less acceptable at the higher dose level. Irradiation affected the respiration rates inside the packages, with lower (10.38%) O 2 and higher CO 2 levels than the control. Irradiation at 1.5 and 3.2 kGy dose levels improved the oxygen barrier capability of the low-density polyethylene (LDPE) bags (7.67% and 4.48%, respectively). Water vapor permeability was unaffected at all the irradiation dose levels. The stiffness of LPDE films did not change due to irradiation treatment. Results from sensory evaluation of produce overall quality suggest a potential fungicidal effect of low-dose irradiation (1.0 kGy) of packaged romaine lettuce hearts without altering the overall quality of the produce as well as the LDPE-packaging characteristics.

Nafion®117 modified by low dose EB irradiation: surface structure and physical properties

Recent progress in the treatment of Nafion®117 film by low dose electron beam (EB) exposure is described. The effect of EB exposure between 0 and 400 μC cm−2 doses is discussed on a structural level and a dual reaction mechanism, involving cleavage of the hydrophilic side chain and subsequent formation of -CO2H units at the site of the polymer backbone, proposed for this system. This work was extended by consideration of the effects of EB irradiation in the presence of different oxygen concentrations, 50 ppm, 550 ppm and 2000 ppm. From these studies we conclude that low dose EB exposure facilitates replacement of the sulfuric acid moieties, located at the terminus of the Nafion® side chain, with carboxylic acid units as the dominant hydrophilic group found in the pores of the ion channels at the Nafion® surface. It has been demonstrated that by increasing the degree of carboxylic acid formation at the site of the polymer backbone the conductivity of the resultant material can be buffered sufficiently so as to compensate for the effect of the subsequent cleavage of the hydrophilic side chains. This result not only confirms the irradiation mechanism postulated but allows significant advantages in the development of membranes with properties optimised for DMFC performance.

Regressing atypical histiocytosis: A case report of control following low dose radiation therapy

A case of regressing atypical histiocytosis with a 10-year local course is reported. Long term control of a large fungating mass was achieved with low dose electron beam irradiation to 1500 cGy. Whereas spontaneous resolution of regressing atypical histiocytosis has been noted in the literature, this case demonstrates that certain lesions may be more aggressive than commonly assumed. In these particularly destructive lesions radiation therapy may have a role.