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PubMed2004

Effect of gamma-irradiation on the biophysical and morphological properties of corn.

The effects of gamma-irradiation on the biophysical and morphological properties of corn plants were investigated. The irradiation doses were 0, 1, 1.5, 2.5, 5, and 10 krad. Corn grains exposed to 1.5 and 2.5 krad showed highly significant changes in all growth parameters. Fluorescence and light absorption spectra of chlorophyll attributed to different doses treatments of corn grains clearly confirmed the superiority of 1.5 krad irradiation dose in stimulating corn plants. Furthermore, the frequency dependence of the relative permittivity and the electric conductivity of the treated samples have been performed and discussed. The obtained results give another support via the biophysical properties for the 1.5 krad irradiation dose to be the most favorable one to improve the plant growth characteristics.

Chlorophyll↗
PubMedDate not supplied

Use of ESR for the detection of irradiated dates (Phoenix dactylifera L.).

One variety (Aple) of Libyan dry dates (Phoenix dactylifera L.) was irradiated in a 60Co source to absorbed doses of 0.8, 1.0, 1.5 and 2.0 kGy. Unirradiated date stone contains a radical with a single line g = 2.0045, feature A. Irradiation to a dose of 2.0 kGy (the recommended dose for fruits in U.K.) induces the formation of additional radicals with signals g = 1.9895 and 2.0159, feature C. The single line having g = 2.0045 decays in both unirradiated and irradiated samples whereas the additional signals g = 1.9895 and 2.0159 remain almost unchanged over a period of time 15 months stored at room temperature and 4 degrees C.

Electron Spin Resonance Spectroscopy↗
PubMed2000

Irradiation to ensure quarantine security for Cryptophlebia spp. (Lepidoptera: Tortricidae) in sapindaceous fruits from Hawaii.

Studies were undertaken to determine whether irradiation treatment at 250 Gy, an accepted treatment for disinfestation of fruit flies in spindaceous fruits from Hawaii, would also disinfest fruit of two species of Cryptophlebia. Cryptophlebia illepida (Butler) was determined to be more tolerant of irradiation than Cryptophlebia ombrodelta (Lower); therefore, C. illepida was the focus for detailed tests. Using the criterion of success in developing to the adult stage, the pattern of tolerance to irradiation in C. illepida was generally eggs < early instars < late instars < pupae. The most tolerant stage potentially occurring in harvested fruits was late (fourth and fifth) instars. Development to adult was reduced slightly in late instars receiving an irradiation dose of 62.5 Gy, whereas development to adult was dramatically reduced in late instars receiving irradiation doses > or = 125 Gy. No C. illepida larvae receiving an irradiation dose > or = 125 Gy emerged as adults and produced viable eggs, indicating sterility can be achieved at doses well below 250 Gy. In large scale tests, when 11,256 late instars were irradiated with a target dose of 250 Gy, 951 pupated (8.4%) and none eclosed as adults. Within the pupal stage, tolerance increased with age; 7- to 8-d-old pupae (the oldest pupae tested) treated with an irradiation dose of 125 Gy produced viable offspring, whereas those treated with a dose of 250 Gy produced no viable offspring. Irradiation of adults with a target dose of 250 Gy before pairing and mating resulted in no viable eggs. Irradiation of actively ovipositing adult females resulted in no subsequent viable eggs. Therefore, the irradiation quarantine treatment of a minimum absorbed dose of 250 Gy approved for Hawaii's fruits will effectively disinfest fruits of any Cryptophlebia in addition to fruit flies.

Animals↗
PubMed2000

Effect of electron beam irradiation on color and microbial bioburden of red paprika.

The effect of irradiation with electron beams on the microbiological quality and color properties of red paprika was examined. The irradiation doses ranged from 0 to 12.5 kGy. The counts performed were total mesophilic aerobic microorganisms, Enterobacteriaceae, coliforms, sulfite-reducing clostridia, molds, and yeasts. It was concluded that molds, yeasts, and sulfite-reducing clostridia were the most resistant species, although a 10-kGy dose of irradiation leads to optimum sanitation. Extractable color and apparent color were analyzed to appraise the incidence of the irradiation treatments in the color properties of red paprika. Extractable color was determined according to the American Spice Trade Association method, and apparent color was analyzed by reflectance using the CIELab color space. Data showed no significant differences between the color properties of irradiated and nonirradiated samples. Irradiation was a suitable procedure to minimize the bioburden of red paprika with small modifications of its color properties.

Capsicum↗
PubMed2003

Effect of gamma irradiation on elimination of aflatoxins produced by apple mycoflora in apple fruits.

The influence of ionizing radiation on the growth of apple mycoflora and the aflatoxins production was investigated. Four strains of fungal isolates, Aspergillus flavus, A. fumigatuis, A. niger, Penicillium expansum, were used. Four doses of gamma radiation were applied (0.5, 1.0, 1.5 and 2.0 KGy). The elimination of aflatoxins under selected conditions was detected by using HPLC techniques. Doses of 0.5 KGy stimulated the production of aflatoxins by all fungi tested while 1.0-2.0 KGy reduced the aflatoxins production. The studies were also carried out to investigate the effect of pre- and post-inoculation of both irradiated and non-irradiated fungal spores on irradiated and non-irradiated apples. The results showed the necessity of irradiation of fresh apple fruits followed by good preservation conditions. The results showed also that the effect of radiation is influences on the apple mycoflora producing aflatoxins and not the apple itself.

Aflatoxins↗
PubMed1976

The effect of methods of sterilization on the nutritive value of protein in a commercial rat diet.

1. The effect on protein quality of treating a commercial rat diet by autoclaving at various temperatures for different periods of time, or by irradiation with 2-5 or 10 Mrd, was studied. True digestibility (TD) and biological value (BV) were measured and the available and total amino acids in the diets were estimated using microbiological and chemical methods. 2. Autoclaving at 121 degrees for 60 min reduced BV, TD and net protein utilization (NPU) more than autoclaving at 134 degrees for 3 min. Availability of amino acids was reduced by both treatments but to a greater extent by autoclaving at 121 degrees for 60 min. Total amino acids were essentially unaffected. Irradiation had no effect on BV, TD, NPU or total amino acids, and the availability of amino acids was also unaffected, with the exception of lysine which was slightly reduced. 3. When the diet was autoclaved at 115 or 121 degrees for 15, 30 or 60 min, or at 134 degrees for 3 min the availability of the amino acids was reduced with increasing time and temperature of treatment. Treatment at 134 degrees for 3 min had an effect on available amino acids similar to treatment at 121 degrees for 15 or 30 min. 4. Ethylene oxide fumigation of the diet caused reduced availability of histidine, methionine and tryptophan but had negligble effect on arginine, leucine and lysine. 5. It is concluded that from a practical point of view irradiation causes least damage to proteins in rodent diets. If such diets are to be autoclaved they should be supplemented with complete protein to counteract amino acid destruction.

Amino Acids↗
PubMed1999

Trained sensory panel and consumer evaluation of the effects of gamma irradiation on palatability of vacuum-packaged frozen ground beef patties.

The objectives for this experiment were to determine the effects of gamma irradiation on 1) the palatability of vacuum-packaged frozen ground beef patties by trained sensory panel and 2) consumer evaluation of the taste of hamburgers made with those patties. Boxes (4.5 kg) of frozen (-28 degrees C) ground beef patties (113.4 g/patty, 19% fat) from a commercial supplier were irradiated at a commercial gamma irradiation facility at one of three levels (0, 3.0, or 4.5 kGy). All boxes were stored at 28 degrees C for 27 to 29 d after irradiation before evaluation by a trained descriptive attribute sensory panel and for 62 to 104 d after irradiation before consumer evaluation. The trained panel evaluated grilled patties for ground beef aroma intensity, off-aroma, and off-flavor on 4-point scales (4 = intense, none, and none; 1 = none, intense, and intense, respectively) and ground beef flavor intensity, tenderness, and juiciness on 8-point scales (8 = extremely intense, tender, or juicy; 1 = extremely bland, tough, or dry). Control patties had more intense (P<.05) ground beef aroma (3.1 vs 2.6), less off-aroma (3.3 vs 2.6), and more intense ground beef flavor (4.9 vs. 4.3) than irradiated patties. However, there were no differences (P>.05) in any sensory trait between frozen ground beef patties treated with 3.0 or 4.5 kGy of gamma irradiation. There were no differences (P>.05) among treatments for tenderness (6.3, 6.6, and 6.7) or juiciness ratings (5.7, 5.9, and 5.9), respectively, for 0, 3.0, and 4.5 kGy. The consumers evaluated taste of a hamburger that included their choice of condiments on a 10-point scale (10 = excellent; 1 = terrible). Hamburgers made with patties treated with 4.5 kGy were rated lower (P<.05) in taste than hamburgers made with either control patties or those treated with 3.0 kGy (6.5, 6.6, and 6.2, respectively, for 0, 3.0, and 4.5 kGy); however, all doses were rated at some level of "fair." These results imply that hamburgers made from ground beef patties irradiated under the conditions of this experiment would encounter little, if any, consumer acceptance problems at the 3.0 kGy dose and only slightly greater problems at the 4.5 kGy dose.

Animals↗
PubMed2004

Oxidative environments decrease tenderization of beef steaks through inactivation of mu-calpain.

This study was designed to test the hypothesis that oxidative conditions in postmortem (PM) tissue decrease calpain activity and proteolysis, subsequently minimizing the extent of tenderization. To achieve different levels of oxidation, the diets of beef cattle were supplemented with vitamin E for the last 126 d on feed, and beef steaks were irradiated early PM. Ten steers were fed a finishing diet with the inclusion of vitamin E at 1,000 IU per steer daily (VITE). Another 10 beef steers were fed the same finishing diet without added vitamin E (CON). At 22 to 24 h PM, strip loins from each carcass were cut into 2.54-cm-thick steaks and individually vacuum packaged. Within 26 h PM, steaks were irradiated at 0 or 6.4 kGy and then aged at 4 degrees C for 0, 1, 3, 7, and 14 d postirradiation. Steaks from each time point were used to determine Warner-Bratzler shear force (WBSF) and calpain activity, and for western blotting of sarcoplasmic proteins and myofibrillar proteins. Calpastatin activity was determined at 0, 3, and 14 d postirradiation. At 1, 3, 7, and 14 d postirradiation, WBSF values of irradiated steaks were higher (P < 0.03) than for nonirradiated steaks. Western blots of troponin-T and desmin showed decreased proteolysis in irradiated samples compared with nonirradiated samples. At 2 d PM, troponin-T degradation products were more evident (P < 0.03) in nonirradiated steaks supplemented with VITE than nonirradiated steaks from the CON diet. Similarly, VITE treatment resulted in steaks with lower (P < 0.05) calpastatin activity at 1 d PM than in steaks from steers fed the CON diet. Irradiation diminished the rate of calpastatin inactivation. Irradiated samples, regardless of diet, had no detectable levels of intact titin or nebulin. Irradiation decreased mu-calpain activity and autolysis, whereas mu-calpain activity was not affected by diet or irradiation. Inactivation of mu-calpain by oxidation during early times PM decreased the amount of myofibrillar proteolysis, thereby decreasing the extent of tenderization of beef steaks.

Animals↗
PubMed1975

Chromosomal aberrations in rats fed irradiated wheat.

The effects on chromosomal aberrations in bone-marrow cells of feeding irradiated wheat to well-fed and malnourished rats were investigated. Rats maintained on low levels of dietary protein (5 per cent) had a higher incidence of breaks and deletions in their bone-marrow chromosomes compared with rats maintained on adequate levels of protein (18 per cient), showing that the level of dietary protein per se can produce structural abnormalities. Feeding of irradiated wheat to rats was associated with increase in the number of polyploid cells in the bone-marrow. The level of protein in the diet did not appear to influence polyploidy.

Animals↗
PubMed2004

Irradiation disinfestation of apple maggot (Diptera: Tephritidae) in hypoxic and low-temperature storage.

Apple maggot, Rhagoletis pomonella (Walsh), is a quarantine pest of apples, Malus domestica Borkhausen, and pears, Pyrus communis L., shipped from much of the United States and Canada. As such, these fruits shipped from infested areas to uninfested areas must undergo a quarantine disinfestation treatment. The objective of this research was to develop irradiation quarantine treatments against apple maggot considering that fruit hosts may be stored under hypoxic or cold conditions when they are irradiated. Hypoxia increased from 30.5 to 35.7 Gy (17%) the estimated dose to achieve 99% prevention of the full pupal stage from irradiated third instars in apples compared with ambient atmospheres. However, 50 Gy completely prevented the full pupa in 22,360 and 15,530 third instars, respectively, irradiated in apples in ambient and hypoxic atmospheres. There was no difference in development to the full pupal stage in apple maggot third instars held at 1 or 24 degrees C when irradiated with 20 Gy. Because the maximum dose measured when 50 Gy was sought was 57 Gy, the latter should be the dose recommended for quarantine disinfestation of host fruits of the apple maggot. Apples and pears tolerate much higher doses.

Animals↗
PubMed2004

Simplified qualitative method for canavanine in seeds and sprouts.

The major stored nitrogen compound in alfalfa seeds is canavanine. To identify this nonprotein amino acid from seed extract and sprout water, a qualitative micro-thin-layer chromatography method was developed. Successful separation and identification was achieved using microsilica plates, a 70:30 ethyl alcohol-water solvent system, and 1% ammonium disodium pentacyanoammineferrate II for color development. This quick method was used to identify canavanine (sensitivity 50 microg) from irradiated and nonirradiated alfalfa and clover seed extracts and alfalfa sprout water. Broccoli and radish seed extracts were negative for canavanine. This simple method is useful to track the release and decrease of canavanine in the sprout water.

Canavanine↗
PubMed2003

Damage of yeast cells induced by pulsed light irradiation.

DNA damage, such as formation of single strand breaks and pyrimidine dimers was induced in yeast cells after irradiation by pulsed light, which were essentially the same as observed with continuous ultraviolet (UV) light. The UV-induced DNA damage is slightly higher than seen with pulsed light. However, increased concentration of eluted protein and structural change in the irradiated yeast cells were observed only in the case of pulsed light. A difference in the inactivation effect between pulsed light and UV light was found and this suggested cell membrane damage induced by pulsed light irradiation. It is proposed that pulsed light can be used as an effective sterilizing method for the yeast Saccharomyces cerevisiae.

Consumer Product Safety↗
PubMed1996

The effect of substrate on the radiation resistance of yeasts isolated from sausage meat.

The radiation resistance of a selection of yeasts isolated from sausages was assessed in phosphate-buffered saline and in sausage meat. The yeasts Candida zeylanoides, Debaryomyces hansenii and Trichosporon cutaneum exhibited sigmoidal survival curves in both substrates whilst the more sensitive Sporobolomyces roseus exhibited an exponential survival curve in buffer but a sigmoidal curve in meat. Irradiating C. zeylanoides, D. hansenii and T. cutaneum in sausage meat changed the shape of their survival curves to significantly alter the calculated parameters Ds (the dose in kGy that must be achieved before reduction in numbers occurs) and D10sig (the dose in kGy required after the shoulder to achieve a 1 log cycle reduction in numbers). The Ds values were reduced while higher D10sig values were obtained demonstrating that the sausage meat contributed a protective effect to these yeasts at higher irradiation doses. For the yeast S. roseus, similar numbers of survivors were recovered from both substrates at initial low irradiation doses (0-0.5 kGy) with the protective effect being demonstrated again at higher doses (> 2 kGy). These findings should be considered when defining a commercial process to reduce the numbers of yeasts in these products.

Animals↗
PubMed2001

Impacts of ionizing radiation on volatile production by ripening gala apple fruit.

Apple (Malus x domestica Borkh., cv. Gala) fruit treated with 0.5 microL x L(-1) 1-methylcyclopropene (MCP) or air (non-MCP) for 12 h at 20 degrees C were exposed to gamma radiation at doses of 0, 0.44, 0.88, or 1.32 kGy at 23 degrees C and then stored at 20 degrees C. Production of volatile compounds was measured on the day of irradiation and 1, 3, 7, 14, and 21 days after irradiation. Both MCP treatment and irradiation inhibited ethylene production. MCP treatment reduced production of all volatile esters and alcohols detected, whereas irradiation inhibited production of most, but not all, esters and some alcohols by non-MCP-treated fruit. The inhibition of volatile production following irradiation increased with dose. Production of methyl and propyl esters was inhibited more than that of other esters following irradiation or MCP treatment. The impact of irradiation on production of esters and alcohols by MCP-treated fruit was minimal. Non-MCP-treated fruit irradiated at 0.44 kGy produced the most esters during the 21-day period at 20 degrees C following irradiation, and the ester production rate in these fruit was comparable to that of the nonirradiated fruit 21 days after irradiation. Fruit treated with doses higher than 0.44 kGy did not recover their ability to produce volatile compounds. These results indicate both MCP and ionizing radiation inhibit production of many aroma compounds produced by ripening apple fruit.

Alcohols↗
PubMed2002

Monitoring of nitrite and N-nitrosamine levels in irradiated pork sausage.

Residual nitrite and N-nitrosamine levels were monitored on irradiated emulsion-type cooked pork sausage in aerobic or vacuum packaging states during storage. The sausage was irradiated at 0, 5, 10, and 20 kGy and stored at 4 degrees C for 4 weeks. The residual nitrite levels were significantly reduced by gamma irradiation (P < 0.05), whereas the vacuum packaging was more effective for nitrite reduction than aerobic packaging during storage. N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) levels were significantly reduced in the vacuum packaged sausage irradiated with 20 kGy after 4 weeks. Reduction of NPYR in aerobically packaged sausage was also found after 4 weeks by irradiating with a 5-kGy or higher dose. NDMA reduction was shown in vacuum packaging and irradiation at 20 kGy. Gamma irradiation was effective in reducing the residual nitrite all throughout storage and N-nitrosamines in sausage after storage.

Animals↗
PubMed1983

[Effects of irradiated wheat flour in the AKR mouse. I. Effects on longevity, morbidity and pathology].

Mouse of AKR strain were fed with wheat flour irradiated at 75.000 rads or with nonirradiated flour during their lifetime. In this first part were analyzed : bodyweight, morbidity, mortality, organ's histology. Were established : higher bodyweight in all animals fed with irradiated flour, this increase is statistically significant only in males and a longer time life in all animals of this group, this last difference is significant in females and in animals together without distinction of sex.

Animals↗
PubMed2003

Status of free radicals in Indian monsooned coffee beans gamma-irradiated for disinfestation.

Free radicals in two cultivars of Indian monsooned coffee beans, gamma-irradiated for hygienic and quarantine purposes, were examined by entrapping the small amount of samples in potassium chloride powder in ESR quartz tubes. In contrast to a prominent free radical signal at g = 2.002, observed in spermoderm (silver skin) and cotyledon (whole seed without skin) parts of normal coffee beans, the same was not discernible in monsooned coffee bean parts of both cultivars. The ESR signal was found to be more prominent in the spermoderm than in the whole seed portion of the normal coffee beans. Common practices of roasting and powdering were found to generate quantitatively more free radicals in coffee beans than gamma-irradiation alone. Phenols, contributing maximally to observed free radical signals in coffee beans, were significantly different in normal and monsooned coffee beans. These observations on insignificant free radical population in irradiated monsooned coffee beans may be attributed to their inherent possession of high water activity, favoring decay of free radicals produced. Textural studies with monsooned coffee beans, before and after mild heat treatments, supported these findings.

Chlorogenic Acid↗
PubMed1991

Decomposition of ochratoxin A by heat and gamma-irradiation.

Up to 50% of initial amounts of 2 and 100 ng/ml ochratoxin A were decomposed after gamma-irradiation of solutions in water, in 2% aqueous NaCl or an aqueous solution of 2% NaCl and NaNO2. Ochratoxin A in these solutions was not decomposed, however, after heating at 20, 121 or 135 degrees C for 15 min.

Food Handling↗