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Irradiation of Maconellicoccus hirsutus (Homoptera: Pseudococcidae) for phytosanitation of agricultural commodities.

Studies on the tolerance of pink hibiscus mealybug, Maconellicoccus hirsutus (Green), to ionizing irradiation were undertaken to determine the dose needed to disinfest commodities of this pest. Overall, radiotolerance of M. hirsutus was found to increase with maturity. Target doses of 50 Gy reduced eclosion of eggs to <50%, but doses as great as 750 Gy did not eliminate hatching during the study. At 100 Gy, M. hirsutus eggs, crawlers, and nymphs were controlled, because progeny were not produced despite crawlers and nymphs living for much longer periods than unexposed individuals. Fecundity of treated crawlers and nymphs was greatly impacted by treatment of 100 Gy; crawlers developing into adults produced no eggs, and 10 adults of 3,983 treated nymphs (0.25%) produced 309 eggs. Few adult females exposed as nymphs deposited eggs because male nymphs died during development, which left the females unfertilized. By comparison, 89% of female nymphs treated at 100 Gy and mated as adults with nonirradiated males produced a total of 1,447 eggs (19 eggs per female). Evidence from this study suggests M. hirsutus reproduces sexually, not parthenogenetically. Adults, the most resistant stage, exposed to target doses of 100 Gy produced eggs that were 1.2% viable, from which a small portion of individuals successfully completed development and produced progeny. A target dose of 250 Gy was sufficient to control adult M. hirsutus because, at that dose, none of the eggs produced by 3,093 irradiated adults eclosed. The minimum dose needed to ensure quarantine security is between 100 and 250 Gy.

Animals↗

Effect of gamma irradiation on storability of apples (Malus domestica L.).

The aim of this study was to investigate the effect of gamma irradiation on storability of the two main apple varieties, Golden Delicious and Starking, in Syria. The experiments were performed in 1995 and 1996. Fruits were irradiated with 0, 0.5, 1.0 and 1.5 KGy. Irradiated and unirradiated fruits were stored at 1 to 2 degrees C and under a relative humidity of 80 to 90%. Weight loss and spoilage due to physiological disorders and fungal diseases were evaluated throughout the different storage periods. Firmness, coloration and pH values were estimated immediately after irradiation. The results showed that, in both varieties, gamma irradiation increased the weight loss after 45 days of storage in apples gathered in 1995 but not in the 1996 season. After 180 days of storage, gamma irradiation had different effects on weight loss depending on the growing year and variety, and increased fungal spoilage. Application of gamma irradiation prevented the growth of Aspergillus niger and the formation of skin scald in 'Golden Delicious' fruits. Immediately after treatment, gamma irradiation increased the softening of fruits, changed their color from green to yellow and decreased the pH value of the juice.

Aspergillus niger↗

Dietary functional ingredients: performance of animals and quality and storage stability of irradiated raw turkey breast.

The objective of this study was to evaluate the effect of dietary functional ingredients vitamin E (VE), Se, and conjugated linoleic acid (CLA), alone or in combination, on the quality of irradiated turkey breast meat. A total of 480 male turkeys (11-wk-old, raised on a cornsoybean basal diet) were randomly allotted to 32 pens and fed 1 of 8 experimental diets (4 pens/treatment) supplemented with none (control), 200 IU/kg of VE (VE), 0.3 ppm Se (Se), 2.5% CLA (CLA), 200 IU/kg of VE + 0.3 ppm Se (VE + Se), 200 IU/kg of VE + 2.5% CLA (VE + CLA), 2.5% CLA + 0.3 ppm Se (CLA + Se), 200 IU/kg of VE + 0.3 ppm Se + 2.5% CLA (VE + Se + CLA) for 4 wk. At 15 wk of age, all birds were slaughtered, and breast muscles of 8 birds from each pen were separated, pooled, and ground. Patties were prepared using the ground meat, aerobically packaged, and irradiated at 0 or 1.5 kGy absorbed dose. Lipid oxidation, color, and volatiles of the patties were measured after 0, 7, and 12 d of storage at 4 degrees C. The content of VE and Se and fatty acid composition of lipids were also determined. Dietary supplementation of VE and CLA increased their concentrations in turkey breast. Dietary CLA decreased monounsaturated and non-CLA polyunsaturated fatty acids content in meat. Irradiation increased (P < 0.05) Hunter color redness value of turkey breast and accelerated lipid oxidation, regardless of dietary treatments. However, dietary VE, Se, and CLA, alone and in combinations, decreased (P < 0.05) lipid oxidation in meat caused by both irradiation and storage. It was concluded that dietary supplementation of VE, Se, and CLA, alone and in combination, improved the storage stability of irradiated turkey breast meat.

Animal Feed↗

Observations of the use of 137caesium radiation to control N-nitrosopyrrolidine formation in bacon.

Several alternatives to the use of nitrite, including irradiation, have been developed to reduce the nitrosamine content in bacon and still retain its microbiological safety and desirable sensory characteristics. This paper presents results obtained from experiments in which 137Cs was used at +5 degrees C. Bacon prepared with 120 or 40 mg/kg sodium nitrite (NaNO2) yielded lower residual nitrite before frying and lower levels of N-nitrosopyrrolidine (NPYR) after frying when irradiated at 3.0 Mrad, compared to doses of 0, 0.75 and 1.50 Mrad. Also, a slight increase in the level of NPYR in fried bacon over the 0 control was noted with 0.75 Mrad. In bacon irradiated with 0-1.5 Mrad in 0.25-Mrad increments, a marked increase was observed at 0.5 Mrad. Bacon from pork bellies irradiated prior to processing had more NPYR after frying than bacon irradiated after processing, suggesting the formation of an additional precursor or some catalytic agent.

Animals↗

Influence of gamma-irradiation and microwaves on the antioxidant property of some essential oils.

The antioxidant property of anise, caraway, cumin and fennel essential oils extracted from untreated, gamma-irradiated and microwaved fruits against sunflower oil oxidative rancidity was evaluated. The fruits were exposed to gamma-irradiation at 10 KGy and to microwaves at low oven power setting for 1 min. The essential oils were added individually (200 ppm) to sunflower oil and the rate of oil oxidation was followed by determining the peroxide value during storage at room temperature. The irradiated and microwaved essential oils exhibited an antioxidant activity and was superior to that of sunflower oil catalysed by a mixture of BHT + BHA (200 ppm) in most cases. The present data show that gamma-irradiation and microwave treatments did not affect the antioxidant property of the essential oils under study. In addition the essential oils extracted from the gamma-irradiated fruits were more effective as an antioxidant in sunflower oil than those produced from microwaved fruits.

Analysis of Variance↗

Evaluation of a gas chromatographic method to identify irradiated chicken, pork, and beef by detection of volatile hydrocarbons.

A method suitable for routine application was used in an interlaboratory study to detect irradiation treatment of chicken carcass, pork, and beef. By using gas chromatographic analysis, 17 participating laboratories determined the quantity of 4 different radiation-induced volatile hydrocarbons (tetradecene, pentadecane, hexadecadiene, and heptadecene) in the fat fraction of coded specimens approximately 3 and 6 months after irradiation. The specimens of each type of meat were supplied by 2 different producers. The dose range tested (0.6-7.5 kGy) included levels commercially used to reduce the number of contaminating microorganisms (1-5 kGy). The method employed permitted a correct identification of irradiated or nonirradiated in 98.3% of the 864 specimens.

Animals↗

Stability of fat during irradiation and subsequent storage of irradiated buffalo meat.

Buffalo meat steaks were irradiated with gamma-rays in doses of 0,550 and 1100 krad and stored at 2 +/- 1 degree C. The changes in lipids extracted from the steaks were investigated. Peroxides and carbonyl compounds accumulated during irradiation and subsequent storage of the irradiated meat. Oxidation products were higher if irradiation was carried out with 1100 krad than with 550 krad. Soaking of the steaks in butylated hydroxy toluene (BHT) and sodium pyrophosphate before irradiation markedly reduced the amount of peroxides and carbonyl compounds formed during irradiation and storage. Treatment of meat muscle 800 V for 45 s reduced weeping but increased slightly the rate of autoxidation of lipids. The browning reaction was slow during cold storage of irradiated meat but increased upon storage of extracted lipids at room temperature.

Animals↗

Effects of ionizing radiation on nitric oxide myoglobin. Part 1. Effects on the NO-haem moiety.

Bovine nitric oxide myoglobin (NOMb) was irradiated with 40-4000 krad of gamma-radiation, and the effects on the haem studied using absorption spectroscopy and electron spin resonance (e.s.r.) spectroscopy. The results show the following behaviour. The bright red colour of NOMb changes to brown upon irradiation. This is similar to changes observed in radiation sterilized. nitrite-containing meats. NOMb becomes progressively denitrosylated, with met-myoglobin (metMb) as the immediate product. Upon increasing doses of radiation (up to 800 krad) at 0 degrees C parallel to NOMb denitrosylation, metMb is gradually converted, by water radiolytic products, to other products, believed to be ferromyoglobin and ferrimyoglobin peroxide. A minor quantity of 'choleglobin-type' pigments may also be formed at the highest doses. Freezing of NOMb has a substantial protective effect against radiation. Native bovine NOMb behaves as a pentaco-ordinate (hfs of 3 peaks with equal intensity); the bond between iron and N epsilon is thus dramatically stretched and weakened. Using a thermal energy analyser, no NO could be detected over irradiated NOMb solution, indicating rapid reaction of NO liberated from NOMb by radiation, with radiolytic products of water.

Animals↗

Influence of dietary vitamin E on behavior of Listeria monocytogenes and color stability in ground turkey meat following electron beam irradiation.

There is growing concern that the free radical scavenging effect of antioxidants added to meats might reduce the antimicrobial effectiveness of ionizing radiation. A study was conducted to determine the effect of vitamin E on the behavior (growth) of Listeria monocytogenes and color stability in turkey meat following electron beam irradiation. Raw ground turkey breast meat from birds fed diets containing 0 (control), 50, 100, and 200 IU/kg of vitamin E was inoculated with a five-strain mixture of L. monocytogenes to give approximately 10(7) CFU/g. Inoculated samples were irradiated at 0, 0.5, 1, and 2 kGy and stored aerobically (12 days) or under vacuum (42 days) at 4 degrees C. L. monocytogenes survivors were determined by plating samples on modified Oxford medium and counting colonies on modified Oxford medium plates after 48 h at 35 degrees C. Meat color was measured using a colorimeter. Irradiation at 2.0 kGy resulted in an approximately 3.5-log reduction of initial numbers of L. monocytogenes. There were no significant differences in D-values (decimal reduction times) for L. monocytogenes in meat irrespective of vitamin E treatment (P > 0.05). Also, vitamin E treatments did not affect growth of the pathogen in aerobic or vacuum-packaged samples following irradiation (P > 0.05). Compared with controls, irradiated meat from birds fed 100 or 200 IU/kg of vitamin E demonstrated significant improvement in color stability (lightness and redness values) during aerobic storage (P < 0.05). Dietary vitamin E (100 to 200 IU/kg) has good potential for improving the color stability of turkey meat without compromising the microbial safety of the irradiated product.

Animals↗

[Sprout inhibition by radiation and chemical treatment in four potato cultivars (author's transl)].

Irradiated and chemically treated potatoes were then stored at 10 degrees C and 80-85% relative humidity. Radiations caused complete inhibition of sprouting and for up to 10 months after harvest the physical and chemical condition of the potatoes remained satisfactory. On the other hand chemical treatment controlled sprouting for up to 7-8 months only. Irradiation and chemical condition of the potatoes rotting. Weight loss was higher in the chemically treated samples. Treatment by radiation did not effect vitamin C and niacin content as compared with chemically treated samples. Irradiation did not cause any change in the sucrose and the total sugar content, as compared with chemical treatment. Total and soluble nitrogen contents were not affected by either treatment. The response to both irradiation and chemical treamtments was only slightly affected by varietal factors provided that the potatoes were healthy and mature at harvest time.

Amino Acids↗

Micronucleus test in mice fed on an irradiated diet.

A mutagenicity study was carried out in mice fed on a gamma-irradiated diet. As an indicator of mutagenic activity, we observed an incidence of micronuclei in erythrocytes. The average body weight of the mice fed on the diet irradiated to dose range of 400-1,000 kGy decreased, and the mice fed on the 800-1,000 kGy-irradiated diet died during the period from 8 to 14 days after the start of feeding. On the other hand, when the mutagenic activity of the irradiated diet was tested by observing occurrence of micronucleus in erythrocytes, no significant increase was recognized. These results indicated that the irradiated diet had no mutagenic activity, even though it possessed a toxic effect on the growth of mice.

Animals↗

[Electron spin resonance spectroscopy as probes for spices. Detection of treatment with ionizing radiation].

Detection of irradiated spices by electron spin resonance (ESR) measurements was not successful in the past because a central line of unknown origin was detected in the ESR-spectra of both irradiated and unirradiated samples. Identification of irradiated samples by measuring the increase of intensity of this signal after irradiation is limited because the signal intensity decreases over a period of some weeks of storage and reaches the range of unirradiated samples. By changing the measurement conditions (low microwave power) we could detect two additional lines on both sides of the main signal. This line pair appears only in the spectra of irradiated spices. A similar line pair was found in the spectra of irradiated nutshells and possibly derives from cellulose radicals in the sample. For some spices, especially paprika, the identification of irradiated samples by detecting these additional lines was possible even after relatively long periods of storage.

Condiments↗

Evaluation of 2-dodecylcyclobutanone as an irradiation dose indicator in fresh irradiated ground beef.

Alkylcyclobutanones (2-ACBs) are radiolytic products formed when fatty acids are irradiated. These cyclobutanones are unique irradiation byproducts and therefore may serve as indicators of irradiation exposure. As only limited information exists about 2-ACB formation in retail meat products, reliable methods that can quantify 2-ACBs and thus estimate irradiation dose in commercial meat products are desired. The cyclobutanone studied in this experiment was 2-dodecylcyclobutanone (2-DCB), which is formed from palmitic acid. The formation of 2-DCB was evaluated in fresh irradiated ground beef patties at two fat levels. Patties containing 15% and 25% fat were irradiated by electron beam at 1.0, 2.0, 3.0, and 4.5 kGy. Commercially available 1-lb irradiated ground beef chubs with different fat levels were analyzed in order to estimate dose absorbed by these samples. The 2-DCB was extracted using supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectroscopy (GC-MS) and was detected in all the irradiated samples. The concentration of 2-DCB increased linearly with dose with R2 = 0.9646 for 25% fat samples and R2 = 0.9444 for 15% fat samples. Further, there was no significant difference in 2-DCB concentrations between the two fat levels. The estimated doses applied to the commercial samples ranged between 1.38 and 1.55 kGy, values consistent with doses normally used in the industry (1.0-2.0 kGy). Our results show that 2-DCB can be used to monitor fresh irradiated beef and approximate the absorbed dose.

Animals↗