Irradiated Wheat Research Articles

NUTRITIONAL ASSESSMENT OF RAW, GAMMA IRRADIATED, MICROWAVE TREATED AND FERMENTED WHEAT GERMS.

Wheat germ was irradiated with two types of radiations; gamma and microwave. Gamma irradiation was used at a dose of 6 k.Gy. Microwave radiation was performed by continuous supply of 200 W/Kg of wheat germ for 3 min, and wheat germ was fermented. The gross chemical composition as well as the caloric value of all studied samples, in addition the mineral composition and vitamins of these studied samples was estimated. The amino acid composition and fatty acids composition were studied as well. The results showed that treated and untreated wheat germ had relatively high content of protein, fat, and minerals. Moreover, it proved that it is a good source of vitamin E. It was also noticed that wheat germ protein was rich in most of the essential amino acids, especially leucine, and lysine. Data revealed that wheat germ is considered as a rich source of fatty acids ,and showed that the dominant fatty acid was the linoleic acid. The data revealed that fermented wheat germ recorded the highest percentages in crude protein (36.42%).However microwave treated wheat germ had the highest content of crude fiber (6.13%) . While gamma irradiated wheat germ recorded the highest percentages of carbohydrates (60.75%). On the other hand, raw wheat germ recorded the highest percentages of the ash (5.00%) on dry weight basis. The data concerning mineral contents of the present study are revealed that the fermented wheat germ had the highest iron, manganese, copper, sodium, potassium and sulphur levels. The data revealed that fermented wheat germ recorded the highest percentages in Vitamin (A) and Vitamin (C).However microwave treated wheat germ had the highest content of vitamin (E). Moreover, the data revealed that there were obvious variations in the amino acid composition and in the fatty acids composition as well among all studied types of wheat germ.

Evaluation of protein content, lysine and sulfur-containing amino acids content and electrophoretic patterns of soluble proteins for gamma-irradiated semolina before and after milling of durum wheat

Influenced of gamma irradiation (0, 0.25, 1, 2.5, 5 and 10 kGy) on total nitrogen, lysine and sulfur-containing amino acids content and electrophoretic patterns of soluble proteins of semolina was studied. The effect of irradiation before and after milling on previous parameters was also investigated. Protein content of semolina was not affected with gamma irradiation before and after milling. Up to 10 kGy dose, cystine and methionine were not significantly changed, although they increased slightly with increasing irradiation dose. Lysine content decreased significantly ( P≤0.05) at irradiation dose higher than 5 kGy. At 10 kGy dose, lysine decreased 5% and 14% for irradiated semolina and that obtained from irradiated wheat grains, respectively. The bands number and intensity of soluble proteins decreased with increasing irradiation dose higher than 5 kGy, as shown on SDS-PAGE electrophoresis. Irradiated semolina and semolina obtained from irradiated wheat grains at 10 kGy showed 13 and 15 bands, respectively. Unirradiated sample showed 19 bands.

Effects of gamma rays irradiation on seed germination and growth of hard wheat

The effects of irradiation with low doses (0, 10, 20 and 30 Gy) of radioactive cobalt (60Co) γ rays on seed germination, shoot and epicotyl growth of hard wheat (Triticum durum Desf.) were investigated under laboratory and glasshouse conditions. Irradiated wheat seeds kept their germination speed and capacity levels compared to the control. However, improvements of +18 and +32% were, respectively obtained in root number and root length at the 20-Gy dose. Moreover, the 20-Gy-irradiation dose generated an increase of +33% in epicotyl length. The 20-Gy-irradiation dose improved the root length by +32% and root number by +75% in plants grown on liquid medium. A lower root length increase of +23% was obtained with the same treatment under glasshouse growing conditions. These results show that the in depth development stimulation of hard wheat roots following gamma ray treatment may be used for drought control.

Relationship between ultra‐weak bioluminescence and vigour or irradiation dose of irradiated wheat

Ultra-weak luminescent analysis is a new way to detect the irradiation dose and the vigour of irradiated wheat. Wheat grain and wheat flour were used in this research for ultra-weak luminescent analysis. The experimental data showed that the bioluminescence intensity of wheat grain sample was different with increasing storage time and increasing dose, and a similar trend appeared in the germination rates of irradiated wheat grain. It was found that the differences in bioluminescence intensities and germination rates of irradiated wheat grain at different doses and storage times were due to the effect of irraditation on the wheat embryo and self-repair during storage. As a result, ultra-weak luminescent analysis cannot be used to detect the irradiation dose of irradiated wheat, but it can be used to determine vigour. Experiments showed that the irradiation dose had a highly significant effect on the bioluminescence intensities of wheat flour when cane sugar was added.

Effect of gamma‐ray irradiation on the physicochemical properties of flour and starch granule structure for wheat

SummaryEffect of gamma irradiation on the physicochemical properties of flour and starch granule structure of wheat was compared to non‐irradiated wheat. The moisture content of wet gluten and titratable acidity of wheat flour were significantly affected by gamma irradiation. This treatment also destroyed the starch granules of wheat grain and their breakage augmented as the dose of gamma irradiation increased, apparently resulting in the increase of small starch granules. Probably, these results were due to the disruption of large molecule, such as proteins, lipids and starch. The irradiated wheat flour for RVA pasting properties (flour viscosity) was also evaluated. Besides the difference in RVA profile, starch pasting curves showed a considerable decrease for six main parameters as gamma irradiation dose at different velocity increased.

Comparison between the effect of γ-irradiation and roasting on the profile and antioxidant activity of wheat germ lipids.

In order to utilize wheat germ, a nutrient-dense byproduct of the wheat milling industry, in various food products, different treatments are used to investigate and stabilize its influence on lipid characteristics. However, there are no reports on the effect of γ-irradiation on the lipid profile of wheat germ. In this study, the impact of γ-irradiation (at radiation doses 1/4, 1/2 and 1 kGy) and roasting at (160 °C for 20 min) on the lipid constituents of wheat germ was examined. Both thermal and irradiation treatments did not have a significant effect on the total lipid recovery or the fatty acid composition of wheat germ lipids. The fatty acid profile was found to be made up of linoleic followed by oleic and palmitic as the major fatty acids. An increase in the content of free fatty acids characterized the lipid profile of the irradiated wheat germ samples. Antiradical properties of lipids from roasted and irradiated samples were analyzed using the bleaching of the stable 1,1-diphenyl-2- picrylhydrazyl radical (DPPH). Lipids from irradiated samples exhibited relatively stronger radical scavenging potential than lipids from roasted wheat germ. It has been concluded that γ- irradiation could be applied for wheat germ preservation, where it might be limited to a dose of 1/4 kGy in the processing.

Effects of Electron Beam Irradiation on Dry Matter Degradation of Wheat Straw in the Rumen

The effect of electron beam irradiation at doses of 100, 200 and 300 kGy on ruminal dry matter degradation kinetics of wheat straw was investigated. Samples were irradiated by electron beam irradiator under identical conditions of temperature and humidity. Nylon bags of untreated or irradiated wheat straw were suspended in the rumen of three Taleshi steers for up to 96 h and resulting data were fitted to non-linear degradation model to calculate degradation parameters of dry matter. Results show that the washout fractions of dry matter increased linearly (p<0.001), but potentially degradable fraction and degradation rate decreased linearly (p<0.001) by electron beam irradiation. As a consequence, the effective degradability of dry matter increased linearly (p<0.001) with increasing irradiation dose. Electron beam irradiation at doses of 100, 200 and 300 kGy increased the effective degradability of dry matter at rumen outflow rate of 0.05/h by about 7, 15 and 18%, respectively. In the condition of this study, electron beam irradiation at dose of 200 kGy appeared to be a suitable dose for improving dry matter degradability of wheat straw in the rumen.

Environmental factors affect efficacy of some essential oils and resveratrol to control growth and ochratoxin A production by Penicillium verrucosum and Aspergillus westerdijkiae on wheat grain

This study determined the efficacy of three essential oils (bay, clove and cinnamon oil) and the antioxidant resveratrol (0–500 μg g −1) on the control of growth and ochratoxin A (OTA) production by Penicillium verrucosum and Aspergillus westerdijkiae (= A. ochraceus) under different water activity ( a w, 0.90, 0.95, 0.995), and temperature (15, 25 °C) conditions on irradiated wheat grain. The most effective treatment (resveratrol) was then tested on natural grain. The ED 50 values for growth inhibition by the oils were 200–300 μg g −1 at the a w and the temperatures tested. For resveratrol, this varied from <50 μg g −1 at 0.90–0.95 a w to >350 at 0.995 a w at both temperatures. The ED 50 values for the control of OTA were slightly lower than for control of growth, with approx. 200 μg g −1 required for the oils and 50–100 μg g −1 of the antioxidant, at 0.90/0.95 a w and both temperatures. In wet grain (0.995 a w), higher concentrations were required. For growth there were statistically significant effects of single-, two- and three-way interactions between treatments except for concentration×temperature and concentration×temperature×essential oil/antioxidant treatment. For OTA control, statistically significant treatments were a w, temperature× a w, concentration×temperature, treatment×concentration, and three-way interaction of concentration× a w×treatment for P. verrucosum and A. westerdijkiae. Subsequent studies were done with the best treatment (resveratrol, 200 μg g −1) on natural wheat grain with either P. verrucosum or A. westerdijkiae at 0.85–0.995 a w and 15/25 °C over 28 days storage. This showed that the populations of the mycotoxigenic species and OTA contamination could be reduced by >60% by this treatment at the end of the storage period.

Optical absorption coefficient of laser irradiated wheat seeds determined by photoacoustic spectroscopy

Present study is concerned with the photoacoustic (PA) assessment of optical absorption coefficient (β) for treated (soaking in the methylene blue dye) and untreated seeds of wheat. The determination of β, based on the Rosencwaig and Gersho model enables the optical absorption coefficient to be assessed directly from the measured amplitude of PA signal. The obtained β values were statistically analyzed. The outcome of the analysis shows significant differences in β values: in the wavelength range from 600 to 700 nm treated (with dye) seeds have higher β than untreated seeds. These seeds were also irradiated (varying time and intensity) with a laser diode emitting at 650 nm. Germination tests were carried out on both, irradiated and control (no irradiated) seeds. The percentage of normal seedlings from treated seeds was found higher (p ≤ 0.05) than from control seeds.

Effect of γ‐Ray Irradiation on Modeling Equilibrium Moisture Content of Wheat

The experimental research found that gamma irradiation dose affected the equilibrium moisture content of wheat at the same relative humidity and temperature of ambient. Values of the equilibrium moisture content decreased with an increasing dose of gamma-ray irradiation during both adsorption and desorption. These were due to the changes of wheat starch granules and their water bound ability caused by different irradiation doses. Factor of irradiation dose was added in 3 widely used models for modeling the equilibrium moisture content of irradiated wheat, and the parameters in models were estimated based on the experimental data. Based on the study of correlation coefficient, mean relative error, and standard error the modified Chung-Pfost equation and the modified Henderson equation were found to fit the desorption and adsorption isotherms for wheat, respectively, in the range of experiment at conditions studied.

DSC studies of retrogradation and amylose–lipid complex transition taking place in gamma irradiated wheat starch

The effect of gamma irradiation ( 60Co) with doses of 5–30 kGy on the amylose–lipid complex transition and retrogradation occurring in gels containing ca. 50% and ca. 20% wheat starch was studied by differential scanning calorimetry (DSC) during heating–cooling–heating cycles (up to three cycles). Transition of the amylose–lipid complex occurs in all the irradiated samples at a lower temperature as compared to the non-irradiated starch. That effect was larger when the radiation dose was higher. A further thermal treatment causes a decrease of the transition temperature in the irradiated samples, with no effect or increase of that temperature observed for the non-irradiated ones. Irradiation hinders retrogradation taking place in 50% gels but facilitates the process occurring in 20% gels. The differences between the irradiated and the non-irradiated samples are more evident in the every next heating or cooling cycle as well as after storage and in the case of ca. 50% suspensions as compared to ca. 20% suspensions. The results point out to the deterioration of the structure of the complexes formed in the irradiated starch as compared to the non-irradiated one.

Potential biocontrol agents for Fusarium head blight and deoxynivalenol production in wheat

Fusarium head blight (FHB) caused by Gibberella zeae (anamorph= Fusarium graminearum) is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. During the last 50 years, several epidemics of FHB of varying degrees of severity have occurred in Argentina. Besides the economic losses due to reduction in grain quality, the main problem is the potential mycotoxin contamination of wheat mainly with deoxynivalenol (DON). Biological control offers an additional strategy that can be used as part of an integrated management to control FHB. A survey was done to search for potential biocontrol agents (BCA) isolated from wheat anthers in Argentina. A total of 354 bacterial strains were screened in two selection steps using a index of dominance ( I D) assay considering environmental parameters such as temperature and water activity in the interaction between pathogen and antagonist. Among the evaluated strains, 22 strains (6%) were able to reduce the growth of F. graminearum. The 22 selected strains reduced the production of DON on irradiated wheat grains by 60–100%. The ability of these strains to control FHB and DON production was evaluated under greenhouse conditions. Nine strains (40.9%) significantly reduced the disease severity by 49–71% ( P⩽0.05). The DON content in spikes, produced by plants in the greenhouse trial, was significantly reduced by 32–100% compared with the control. Five strains decreased mycotoxin content to undetectable levels. From this study we identified two strains, Brevibacillus sp. BRC263 and Streptomyces sp. BRC87B, to be tested in combination for potential control of FHB.

Effect of Gamma-ray Irradiation on Drying Characteristics of Wheat

Wheat, pre-treated by gamma-ray irradiation, was air-dried and the influence of irradiation dose, air temperature, and initial moisture content of wheat on drying rate and surface temperature was investigated. Irradiation dose, air temperature, and initial moisture content of wheat affected drying characteristics. Drying rates increased with an increase in dose and temperature. Surface temperature of wheat samples increased with increasing dose at the same drying rate but decreased with increasing dose at the same moisture content. These changes of drying characteristics of irradiated wheat samples were the result of wheat cell structure changes caused by gamma-ray irradiation. It was clear from the microscopic observation that increasing irradiation dose reduced cell-wall thickness or eventually destroyed the cell-wall, causing the cytoplasm to leak from its own cell.

EPR spin probe investigation of irradiated wheat, rice and sunflower seeds

TEMPO and 4-nitro-TEMPO spin probes were used to monitor dose-dependent changes in the EPR spectra of irradiated wheat and rice embryos and sunflower embryo parts. Rice embryos were studied in the 233–293K temperature range using 4-nitro-TEMPO. TEMPAMINE, TEMPYO and DTBN spin probes were also studied for their applicability in the determination of irradiated seeds. All the recorded spectra were simulated, and spectral parameters and partition of the probes among various domains were determined. Despite the contribution of the signal from extracellular regions, it was possible to detect the changes in the water/lipid ratios with dose. The hydrophilic character of the probe alone was not sufficient to distinguish the different doses of irradiation. Line widths and rotational correlation times of various domains within embryo also play an important role. Partition after dehydration was another measure in the selection of the suitable probes for irradiation studies. Better results were obtained in dehydrated embryos for the probes preferring lipid bodies.

ESR detection of wheat flour before and after irradiation

We revealed free radicals in wheat flour before and after γ-ray irradiation and their thermal behavior during heat-treatment using electron spin resonance (ESR) spectroscopy. The ESR spectrum of wheat flour before irradiation consists of a sextet centered at g = 2.0 and a singlet signal at the same g-value position. The first one is attributable to a signal with hyperfine (hf) interactions of Mn 2+ ion (hf constant: 7.4 mT). The second is originated from carbon-centered radical. Upon γ-ray irradiation, however, a new signal with two triplet lines at the low and high field ends was detected in wheat flour on top of the Mn 2+ sextet lines. We analyzed the triplet ESR lines as powder spectra (rhombic g-tensor symmetry) with nitrogen ( 14N) hyperfine interactions. This indicates that a new organic radical was induced in the conjugated protein portion of wheat flour by the γ-ray irradiation. Intensity of the organic free radical at g = 2.0 detected in irradiated wheat flour increased monotonically by the thermal treatment. The analysis of the time-dependent evolution and decay process based on the theory of transient phenomena as well as the nonlinear least-squares numerical method provided a unique time constant for the radical evolution and decay in wheat flour during the heat-treatment.

照射小麦粉に誘導される有機フリーラジカルの加熱時の挙動

Using electron spin resonance (ESR) spectroscopy, we revealed the thermal behavior of radicals as induced by irradiation on wheat flour. Upon irradiation and also baking, the organic free radical, i.e., the g=2.0 signal was detected. Organic free radical is increasing by radiation dose level. By heat treatment, the organic free radicals in irradiated wheat flour increased exponentially to heating duration. With baking, the organic free radicals increased. The yield of radicals from irradiation and baking was also same.

放射線照射小麦粉中に誘導されるラジカルの熱減衰挙動―電子スピン共鳴分光法による検出―

放射線照射小麦粉中に誘導されるラジカルの熱減衰挙動―電子スピン共鳴分光法による検出―

The influence of γ-irradiation on some biological activities and electrophoresis patterns of wheat grain albumin fraction

Water-soluble proteins were extracted from irradiated wheat grain for the purpose of assaying biological activities, reducing sugars content and SDS–PAGE electrophoresis. The differences between samples after γ-irradiation were tested by analysis of variance at the level of significance ( P ⩽ 0.05). Ionising radiation (0.05–10 kGy) caused an increase in the activity of endogenous amylases, statistically significant at doses of 5 and 10 kGy ( P ⩽ 0.05), which was well correlated with the highest extractable protein content. γ-Irradiation of wheat grain at a dose of 0.05 kGy caused an increase of inhibition activity against Sitophilus granarius L. α-Amylase, whereas there was a decrease at 10 kGy ( P ⩽ 0.05). On the other hand, grain irradiated by 0.5 and 1 kGy doses showed a significant increase in inhibition activity against α-amylase of Tribolium confusum Duv. ( P ⩽ 0.05) while at the remaining doses the inhibition activity was on the same level as the control grain. Decrease of Ephesitia kuehniella Zell. α-amylase was observed only at 5 kGy radiation dose ( P ⩽ 0.05). At the remaining doses this activity was comparable to non-irradiated grain. The highest increase of antiamylolytic activity against human saliva α-amylase was noted in albumin proteins of wheat grain treated by γ-radiation doses >0.5 kGy while there were decreases at radiation doses <0.5 kGy ( P ⩽ 0.05). The increase of inhibition activity against hog pancreas α-amylase was noted at radiation doses 0.1 kGy ( P ⩽ 0.05). γ-Radiation doses of 0.05, 0.5 and 1 kGy caused an increase of the antitryptic activity while 10 kGy decreased this activity ( P ⩽ 0.05). SDS–PAGE electrophoresis patterns of albumin sample at 0.1 kGy showed 15 proteins while in the control sample only 11 bands were found. Among studied wheat albumins, the lower protein bands 5 and 8 were detected in wheat grain samples irradiated by 10 and 0.5 kGy, respectively. The differences in inhibitor activities and electrophoretic protein bands of wheat albumin from γ-irradiated wheat grain give additional evidence that these proteinaceous inhibitors against enzymes studied are different in nature.

Temperature and water activity effects on growth and temporal deoxynivalenol production by two Argentinean strains of Fusarium graminearum on irradiated wheat grain

The objective of this study was to determine the effects of water activity ( a W; 0.900–0.995), temperature (5, 15, 25 and 30 °C), time of incubation (7–49 days) and their interactions on mycelial growth and deoxynivalenol (DON) production on irradiated wheat grain by two strains of Fusarium graminearum isolated from wheat ears in Argentina . Optimal a W levels for growth were in the range 0.950–0.995 with a temperature optima of 25 °C. Maximum growth rates were obtained at the highest a W (0.995) and 25 °C for both strains. No growth was observed at 5 °C regardless of the a W levels assayed. Both strains were able to growth at the lowest a W assayed (0.900), although the temperature ranges allowing growth at this minimal a W was 15–25 °C. DON was produced the most rapidly (7 days) when incubated at 25 °C and 0.995 a W. All other conditions required 7–14 days before DON was produced on grain. Maximum amounts of DON for both strains were produced at the highest a W treatment (0.995) after 6 weeks at 30 °C. The range of DON concentrations varied considerably (5 to 140,000 ng g − 1 ) depending on a W and temperature interaction treatments. Production of DON occurred over a narrower range of a W (0.995–0.95) than that for growth (0.995–0.90). DON was more rapidly produced at 25 °C but the maximum amount produced was at 30 °C. Two-dimensional profiles of a W × temperature were developed from these data to identify areas where conditions indicate a significant risk from DON accumulation.

Water, temperature and gas composition interactions affect growth and ochratoxin A production by isolates of Penicillium verrucosum on wheat grain

To examine the effect of interactions between water, temperature and gas composition on growth and ochratoxin A (OTA) production by isolates of Penicillium verrucosum in vitro and in situ on grain-based media and wheat grain. Three isolates of P. verrucosum were examined in relation to radial growth rate and OTA production, and to interacting conditions of water activity (a(w)), temperature and gas composition on a milled wheat medium. Subsequently, detailed temporal studies were carried out on gamma irradiated wheat grain over the range 0.75-0.995 a(w), 10-25 degrees C and air, 25 or 50% CO(2). This showed that optimum growth of P. verrucosum was at 0.98 a(w) in vitro at 25 degrees C, but at 0.95 a(w) and 25 degrees C on wheat grain. The a(w) minimum for growth was about 0.80 a(w), although no OTA was produced under this condition even after 56 days. Significant inhibition of growth and OTA production occurred with 50% CO(2), and 0.90-0.995 a(w) at 25 degrees C. The optimum and marginal conditions for growth and OTA production on wheat grain have been identified. At least 50% CO(2) is needed to inhibit growth and OTA production by >75% in moist grain (0.90-0.995 a(w)). First detailed identification of optimal and marginal interacting conditions of water/temperature and gas composition on growth and OTA production by P. verrucosum on wheat grain. This is a critical component of the postharvest management strategy for minimizing contamination by this important mycotoxin and predicting risk, based on environmental conditions, during drying and storage.