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At least 577 records · Page 32Linked to original sources
PubMed1991

Effect of surface sterilization, fumigation and gamma irradiation on the microflora and germination of barley seeds.

Sodium hypochlorite (NaOCl) and mercuric chloride (HgCl2) surface sterilization, methyl bromide and propylene oxide fumigation and gamma irradiation treatments were compared for their effectiveness in killing microorganisms on or within barley seeds. Surface sterilization with 12.5, 25 or 50% (v/v) NaOCl for 5, 15 or 30 min, decreased Fusarium spp., Epicoccum purpurascens, and Bacillus spp. but did not kill Alternaria alternata. However, surface sterilization with 0.1 or 0.2% (w/v) HgCl2 for 3 min significantly decreased A. alternata, Fusarium spp. and E. purpurascens but Bacillus spp. were only killed by 0.3% (w/v) HgCl2 used for 10 min, which also decreased seed germination. Aspergillus flavus inoculated onto barley seeds as spores, was completely killed by surface sterilization with NaOCl but not with HgCl2, while Fusarium culmorum was killed by both NaOCl and HgCl2 treatments. Fumigation with methyl bromide yielding a concentration-time product of 3000 mg h l-1 or with propylene oxide giving a concentration-time product of 2400 mg h l-1 eliminated all filamentous fungi but Bacillus spp. and yeasts survived, and both treatments adversely affected seed germination. Gamma irradiation at a dose of 4 kGy eliminated most Alternaria, Fusarium and Epicoccum spp. but a dose of 12 kGy was required to kill Bacillus spp., yeasts and Aureobasidium pullulans. Germination was improved slightly up to a dose of 8 kGy but gradually decreased with increase in dosage to 15 kGy of gamma irradiation.

Alternaria↗
PubMed2003

Influences of gamma-irradiation and storage on the carotenoids of sun-dried and dehydrated paprika.

The effects of drying methods, gamma-irradiation, and storage on the carotenoids (capsanthin, capsorubin, zeaxanthin, capsolutein, violaxanthin, beta-carotene, and beta-cryptoxanthin) of paprika were investigated. Sun-dried and dehydrated paprika samples were irradiated in a (60)Co gamma-irradiator at five doses (0, 2.5, 5.0, 7.5, and 10 kGy) in polyethylene bags and stored for 10 months at ambient temperature. Individual carotenoid analyses were carried out on the paprika and fresh red pepper during a 2 month period using the reverse phase HPLC technique. The concentrations of capsanthin and capsorubin, which are responsible for the attractive red color of sun-dried paprika, were higher than those of dehydrated paprika. Higher irradiation doses and a longer storage period resulted in a significant (P < 0.01) reduction of all the carotenoids, except capsorubin. There was no significant (P < 0.05) effect of irradiation dose on capsorubin destruction. The decrease of red carotenoids, for all irradiation treatments, was less than that of the storage period. Even the highest irradiation dose, 10 kGy, caused a 11.1% capsanthin reduction; however, 10 months of storage at the ambient temperature caused a 42.1% reduction of capsanthin. Yellow pigments of paprika (zeaxanthin, capsolutein, violaxanthin, beta-carotene, and beta-cryptoxanthin) were significantly (P < 0.01) decreased by all treatments. These yellow pigments were also found to be at high levels in those sun-dried samples with red pigments. This difference could be caused by the contribution of pigment biosynthesis during the sun-drying period. The most significant pigment reduction was realized in the processing and storage conditions of paprika, rather than in the irradiation process.

Capsicum↗
PubMed1979

Radiation resistance and injury of Yersinia enterocolitica.

The D values of Yersinia enterocolitica strains IP134, IP107, and WA, irradiated at 25 degrees C in Trypticase soy broth, ranged from 9.7 to 11.8 krad. When irradiated in ground beef at 25 and -30 degrees C, the D value of strain IP107 was 19.5 and 38.8 krad, respectively. Cells suspended in Trypticase soy broth were more sensitive to storage at -20 degrees C than those mixed in ground beef. The percentages of inactivation and of injury (inability to form colonies in the presence of 3.0% NaCl) of cells stored in ground beef for 10 days at -20 degrees C were 70 and 23%, respectively. Prior irradiation did not alter the cell's sensitivity to storage at -20 degrees C, nor did storage at -20 degrees C alter the cell's resistance to irradiation at 25 degrees C. Added NaCl concentrations of up to 4.0% in Trypticase soy agar (TSA) (which contains 0.5% NaCl) had little effect on colony formation at 36 degrees C of unirradiated Y. enterocolitica. With added 4.0% NaCl, 79% of the cells formed colonies at 36 degrees C; with 5.0% NaCl added, no colonies were formed. Although 2.5% NaCl added to ground beef did not sensitize Y. enterocolitica cells to irradiation, when added to TSA it reduced the number of apparent radiation survivors. Cells uninjured by irradiation formed colonies on TSA when incubated at either 36 or 5 degrees C. More survivors of an exposure to 60 krad were capable of recovery and forming colonies on TSA when incubated at 36 degrees C for 1 day than at 5 degrees C for 14 days. This difference in count was considered a manifestation of injury to certain survivors of irradiation.

Animals↗
PubMed1994

[Chemiluminescence method for the detection of radiation-induced oxidation products in fat-containing foods].

Radiation-induced oxidation of fatty foods was detected by a chemiluminescence method. Hazelnuts, peanuts and poultry were used as foodstuff samples. Additional investigations were performed with a model system and sunflower oil. The irradiation of the samples was carried out in a x-ray-fluorescence-apparatus. Thereby it is to note that the G-value of the x-ray-radiation is much higher than the G-value of a cobalt-60-source normally used for irradiation of food. A dependence of the integral of the light curve on the irradiation doses could be proved. Investigations with model systems which contained different amounts of alpha-tocopherol showed a decreasing chemiluminescence signal at low irradiation doses in presence of alpha-tocopherol. At higher doses the chemiluminescence signal enlarges with increasing amounts of alpha-tocopherol because irradiation products of alpha-tocopherol overlay its antioxidative effect. Irradiated poultry samples differ significantly from unirradiated samples after a deep-freeze storage of 26 weeks. A quantification of the doses is not possible without knowledge of the storage time, because the integrals decrease differently after irradiation during storage. In any case the chemiluminescence method is useful as a "screening method" for the detection of irradiation of foodstuffs with the possibility of automation and high sensitivity.

Animals↗