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PubMed2003

Effect of gamma-irradiation on the lipid profile of nutmeg (Myristica fragrans Houtt.).

The effect of gamma-irradiation on the lipid constituents of nutmeg (Myristica fragrans) was examined at radiation doses between 2.5 and 10 kGy. The fatty acid composition of the triacylglycerol, the major lipid component, was found to be made up of myristic (90%), palmitic (6%), lauric (3%), petroselinic (0.13%), and stearic acids (0.5%) as determined by gas chromatography-mass spectrometry. A dose-dependent decrease in the triacylglycerol content and a concomitant increase in free fatty acids characterized the lipid profile of the irradiated spice. This suggested a breakdown of acylglycerols during radiation processing, resulting in the release of free fatty acids. These changes were found to be significant at doses above 5 kGy. The impact of the above changes on the flavor of the spice is discussed. These studies suggest that radiation processing of nutmeg should be limited to a dose of 5 kGy.

Fatty Acids↗
PubMed1993

The freezing and thawing of water in poultry meat and vegetables irradiated by electrons at doses of 0.1-4 kGy.

Poultry meat and some vegetables, irradiated by 5 MeV electrons (0.1-4 kGy), were analysed by differential scanning calorimetry, from 24 h after irradiation. The temperature and enthalpy transitions of the water contained in the irradiated samples were measured and compared with those of unirradiated samples. We analysed 18 meat and 10 vegetable samples for each irradiation dose together with a similar number of unirradiated controls. The mean supercooling temperatures of water in the irradiated poultry meat samples and in some vegetables are significantly lower than those of controls. Moreover, the freezing enthalpies of the irradiated poultry breast are significantly lower than those of controls, while they are unchanged in the other cases. The mean ice melting temperatures and enthalpies are similar for all samples. The amount of the lowering of the water-ice transition depends on the nature of the sample and is highest in poultry breast and lowest in vegetables.

Electrons↗
PubMed1980

Long-term feeding studies in mice fed a diet containing irradiated fish. I. Multigeneration reproduction, mutagenicity, teratology, and longevity studies.

A wholesomeness feeding study was carried out in mice fed equal amounts of cod or redfish, comprising 45% of the diet. Three groups of animals received either irradiated [1.75 kGy (175 krad)] fish, non-irradiated fish or stock ration. A 90-day subchronic study, a multigeneration reproduction, a dominant lethality and a teratology study were carried out together with an 80-week oncogenic study on the F1 generation. No adverse effects were noted on growth, reproduction and litter behaviour, in relation to dominant lethality, teratogenicity or oncogenicity.

Animals↗
PubMed1976

Effect of dietary lactose at levels comparable to human consumption on cholesterol and bile acid metabolism of conventional and germfree rats.

In recent years, the use of milk products and the concomitant intake of lactose have been tentatively linked to the etiology of cardiovascular disease. An effect of lactose on the microbial modification of acid and neutral sterols has been suggested. In the present study lactose intake, ranging up to 30% of total diet increased beta-muricholic (beta-MC) but not cholic acid concentrations in conventional (CV) rat small intestine to the extent that at the 20% and 30% intake level, the intestinal cholic: beta-MC ratio approached that in germ-free (GF) rats. Total intestinal bile acid (BA) content increased by approximately 1/3, but remained at less than half the value found in GF rats. At lactose intake levels within a range corresponding to the consumption of dairy products often recommended for adult man (5% to 10%) only moderate changes in intestinal, and little change in fecal BA were found during and after the 3 months experimental period. Intestinal beta-MC was increased in the presence and in the absence of an intestinal microflora. Experiments with GF rats fed 10% lactose or 10% maltose indicated that this increase is evoked similarly by both carbohydrates. The slight increase in serum cholesterol levels seen with disaccharide feeding, which became evident only in the GF rats, was again not specific for lactose. No influence was found of lactose feeding on liver cholesterol values. Comparison of CV rats fed nonsterile and radiation-sterilized lactose-containing diets suggested that this mode of sterilization has only a minor influence on the resulting data. When GF experiments are to be incorporated, sterilazation of diet by irradiation with 3.5 to 4.0 X 10(6) Rad is preferable to autoclaving. The present data indicate that no major effect specifically related to a normal dietary intake of lactose on cholesterol and BA metabolism of the adult rat could be demonstrated for the duration of these experiments.

Animals↗
PubMed1998

Inactivation of Escherichia coli O157:H7 in apple juice by irradiation.

Three strains (932, Ent-C9490, and SEA13B88) of Escherichia coli O157:H7 were used to determine the effectiveness of low-dose gamma irradiation for eliminating E. coli O157:H7 from apple juice or cider and to characterize the effect of inducing pH-dependent, stationary-phase acid resistance on radiation resistance. The strains were grown in tryptic soy broth with or without 1% dextrose for 18 h to produce cells that were or were not induced to pH-dependent stationary-phase acid resistance. The bacteria were then transferred to clarified apple juice and irradiated at 2 degrees C with a cesium-137 irradiator. Non-acid-adapted cells had radiation D values (radiation doses needed to decrease a microbial population by 90%) ranging from 0.12 to 0.21 kGy. D values increased to 0.22 to 0.31 kGy for acid-adapted cells. When acid-adapted SEA13B88 cells were tested in five apple juice brands having different levels of suspended solids (absorbances ranging from 0.04 to 2.01 at 550 nm), radiation resistance increased with increasing levels of suspended solids, with D values ranging from 0.26 to 0.35 kGy. Based on these results, a dose of 1.8 kGy should be sufficient to achieve the 5D inactivation of E. coli recommended by the National Advisory Committee for Microbiological Criteria for Foods.

Beverages↗
PubMed1996

Technological and chemical characters of bread prepared from irradiated wheat flour.

The present work is a part of research programme aimed to use gamma irradiation to decrease the growth of fungi and the concentration of mycotoxines which present naturally in collected samples of wheat flour from Egyptian markets (first part). To follow the technological, rheological and chemical characters of bread "Balady" common type in Egypt, same samples of wheat flour were irradiated with 2, 4 and 8 kGy for these purposes. The Egyptian bread type (Balady) had been prepared from irradiated and non-irraidated samples. The chemical analysis proved a significant induction in reducing sugars (RS) which increased gradually with increasing doses as 16.75%, 30.30%, 43.24% after using 2, 4 and 8 kGy respectively. Same trend was observed with total sugars (TS), less changes were observed in non-reducing sugars (NRS) and starch content. Results obtained showed that an actual reduction in dough development time, stability, weaking of dough and height of bread especially for irradiated samples at 4 and 8 kGy but 2 kGy was less effective. The reduction of Alkaline Water Retention Capacity (AWRC) was clear at high doses whereas 2.0 kGy improved the freshness of aged "balady" bread. Concerning, the evaluation of organoleptic characters of bread as judged by the panelists, all the samples were accepted either irradiated or not. But, the lowest values of acceptance resulted from irradiated samples with 4 and 8 kGy. Therefore, using 2 kGy can be recommended for keeping quality of wheat flour to avoid the infestation or pathogenic infection. Whereas high doses (4-8 kGy) can be use for eliminating the mycotoxins with some changes of quality which can be overcome by using some additional matters to get more acceptable bread and less changes in technological characters.

Bread↗
PubMed2006

An electron spin resonance study of gamma-ray irradiated ginseng.

Using electron spin resonance (ESR) spectroscopy, we revealed the presence of four radical species in gamma-ray irradiated ginseng (Agaliaceae). Before irradiation, the representative ESR spectrum of ginseng is composed of a sextet centered at g = 2.0, a sharp singlet at the same g-value, and a singlet at about g = 4.0. The first one is attributable to a hyperfine (hf) signal of Mn2+ ion (hf constant: 7.4 mT). The second one is due to an organic free radical. The third one is originated from Fe3+. Upon gamma-ray irradiation, a new ESR (the fourth) signal was detectable in the vicinity of g = 2.0 region. The progressive saturation behaviors of the ESR signals at various microwave power levels were indicative of different relaxation time for those radicals. The anisotropic ESR spectra were detected by the angular rotation of the sample tube. This is due to the existence of anisotropic microcrystalline in the ginseng powder sample.

Dose-Response Relationship, Radiation↗
PubMed1977

Influence of intestinal microbes on heat production in germ-free, gnotobiotic and conventional mice.

To observe the influence of intestinal microbes on energy metabolism, male ICR strain germ-free (GF) mice, gnotobiotic (GB) mice, produced from GF mice monocontaminated with Staphylococcus epidermidis (Staph.) at three weeks of age, and conventional (CV) mice were used. Metabolizable energy, heat production and net energy (gain) per mouse were measured for three weeks when the mice were given 5 Mrad 60Co irradiated purified whole-egg protein diet from 5 to 8 weeks of age. With respect to metabolizable energy and heat production per mouse or per kg of metabolic body size for three weeks, CV mice gave the highest values, followed by GB and GF mice. GV mice showed the highest net energy (gain) followed by GF mice, with GB mice having the lowest value.

Animals↗
PubMed1994

Effect of thermal treatments on the chemical and biological value of irradiated and non-irradiated cowpea bean (Vigna unguiculata L. Walp) flour.

Chemical and nutritional characteristics of irradiated and nonirradiated cowpea bean at 0.2 kGy submitted to several thermal treatments were studied. The cowpea bean flours irradiated at 0.2 kGy were superior to those non-irradiated concerning digestibility and the flours submitted to microwave oven were superior to those cooked under low pressure, autoclaved or even raw from the nutritional point of view. As to the presence of anti-nutritional factors, the results showed that the variety of cowpea bean under research presented neither trypsin inhibitor nor haemagglutinin activity, however, regarding tannin, a 0.006% content was found and considered negligible.

Analysis of Variance↗
PubMed1981

Mutagenicity studies on alcohol extracts from gamma-irradiated potatoes--preparation of samples and their chemical analysis.

The preparation of alcohol extracts from gamma-irradiated potatoes of the "Danshaku" variety and their chemical aspects were studied. The final concentrate of alcohol extracts from potatoes showed pH values of 3-4. The o-quinones or "radiotoxins" reported by Kuzin, et al. were not detected in the alcohol extracts from potatoes of this variety by high performance liquid chromatography (HPLC) analysis, paper chromatography and the model enzymatic experiment.

Alcohols↗
PubMed2002

Influence of gamma-irradiation and maize lipids on the production of aflatoxin B1 by Aspergillus flavus.

The effect of gamma-irradiation and maize lipids on aflatoxin B1 production by Aspergillus flavus artificially inoculated into sterilized maize at reduced water activity (aw 0.84) was investigated. By increasing the irradiation doses the total viable population of A. flavus decreased and the fungus was completely inhibited at 3.0 kGy. The amounts of aflatoxin B1 were enhanced at irradiation dose levels 1.0 and 1.5 kGy in both full-fat maize (FM) and defatted maize (DM) media and no aflatoxin B1 production at 3.0 kGy gamma-irradiation over 45 days of storage was observed. The level in free lipids of FM decreased gradually, whereas free fatty acid values and fungal lipase activity increased markedly by increasing the storage periods. The free fatty acid values decreased by increasing the irradiation dose levels and there was a significant enhancement of fungal lipase activity at doses of 1.0 and 1.50 kGy. The ability of A. flavus to grow at aw 0.84 and produce aflatoxin B1 is related to the lipid composition of maize. The enhancement of aflatoxin B1 at low doses was correlated to the enhancement of fungal lipase activity.

Aflatoxin B1↗
PubMed1983

The influence of radapertization upon some sensory properties of black pepper.

Radapertization may be used as an effective method for sterilization of spices. A possible influence of irradiation upon the sensoric qualities should be considered in this context. Therefore the objectives of the work were: --to determine the influence of the irradiation of pepper upon its sensoric quality --to determine the qualitative changes of volatile chemical substances under the influence of the irradiation of pepper --to determine correlation between changes resulting from irradiation and the sensoric quality of pepper. The spice was irradiated with doses of 10, 20, 40 and 60 kGy. Thresholds of recognition and difference were determined. It was established that the quantity of the dose is related to the values of thresholds mentioned above. The larger the dose was the less intensive the flavour became and the higher the thresholds. These interdependences were written in a form of mathematical formulas. A significant influence of irradiation upon the decrease of the quantity of essential oils and carbohydrates was noticed. These relations were also presented in a form of mathematical formulas. The work provides evidence for the fact that there is a relation between the results of sensoric assessments and the chemical characteristics (the content of volatile carbonyl, sulphuric and nitrogenic substances). Correlation between these factors was determined on the basic statistical analysis of the results obtained during our investigations.

Chemical Phenomena↗
PubMedDate not supplied

Effect of irradiation dose, storage time and temperature on the ESR signal in irradiated oat, corn and wheat.

Results obtained for electron-irradiated oat, corn and wheat kernels are discussed. The applied irradiation doses were up to 160 kGy. For doses up to approx. 50 kGy the number of free radicals produced by the irradiation is linear with the absorbed dose; moreover, the decay at room temperature in the dark or in the presence of light is quite similar. These facts point to the possible use of these kernels as dosimeters. An analysis of the free radical decay as a function of time and temperature shows the contribution of at least three types of radicals, whose half-lifes, radiochemical yields and activation energies are given.

Avena↗
PubMed1998

Fate of gamma-irradiated Listeria monocytogenes during refrigerated storage on raw or cooked turkey breast meat.

The radiation resistance and ability of Listeria monocytogenes ATCC 7644, 15313, 43256, and 49594 to multiply on irradiated, air-packed, refrigerated raw or cooked turkey breast meat nuggets (ca. 25 g) and ground turkey breast meat was investigated. Gamma-radiation D values for L. monocytogenes were significantly different on raw and cooked nuggets, 0.56 +/- 0.03 kGy and 0.69 +/- 0.03 kGy, respectively; but they were not significantly different (P < or = 0.05) on raw and cooked ground turkey meat. High populations (approximately 10(9) CFU/g) of L. monocytogenes declined during 14 days of storage at 4 degrees C in both irradiated and nonirradiated samples of raw but not of cooked ground turkey breast meat. A moderate inoculum (approximately 10(3) CFU/g) did not survive a radiation dose of 3 kGy. The population increased in cooked but not in raw samples of irradiated ground turkey meat stored at either 2 or 7 degrees C for 21 days. The D value changed significantly from 0.70 +/- 0.04 to 0.60 +/- 0.02 kGy when the product was cooked to an internal temperature of 80 degrees C before irradiation. Growth on either raw or cooked turkey meat did not alter the radiation resistance of L. monocytogenes. Analyses were performed for pH, aw, moisture, and reducing potential of raw and cooked turkey meat and for pH, amino acid profile, thiamine, and riboflavin contents of aqueous extracts of raw and cooked turkey meats without identifying the factor or factors involved in differences in the survival and multiplication of L. monocytogenes on raw and cooked meat.

Animals↗
PubMed1986

[Effect of ultraviolet-irradiated milk on biochemical indices in the blood serum of calves].

Studies were carried out to establish the effect of ultraviolet in vitro treatment of milk, using special device, on the state and changes of some biologic indices of blood in calves in feeding them with milk within the age interval of 10 to 70 days. The irradiated milk was found to have a favourable effect on the physiologic state of calves, their development, and daily weight gain. Useful changes took place also with regard to the albumin-globulin ratio index which consisted in the rise of the gamma-globulin fractions to the detriment of alfa-globulins. The content of vitamin D was enhanced and made more stable in the serum over the entire experimental period.

Animal Feed↗
PubMed1975

Low-temperature irradiation of beef and methods of evaluation of radappertization process.

An inoculated, irradiated beef pack (1,240 cans) was conducted for the determination of microbiological safety for unrestricted human consumption. Each can contained a mixture of 10(6) spores of each of 10 strains of Clostridium botulinum (5 type A and 5 type B), or a total of 10(7) spores/can. The cans were irradiated to various doses (100 cans/dose) with 60Co gamma rays at -30 +/- 10 C, incubated at 30 +/- 2 C for 6 months, and examined for swelling, toxicity, and recoverable botulinal cells. The minimal experimental sterilizing dose based on nonswollen, nontoxic sterile cans were 2.2 less than experimental sterilizing dose based on nonswollen, nontoxic sterile cans was 2.2 less than experimental sterilizing dose less than or equal to 2.6 Mrad. Using recoverable cells as the most stringent criterion of spoilage, and assuming the conventional simple exponential (without an initial shoulder) rate of spore kill, the "12D" dose was 3.7 Mrad when estimated on the basis of mixture of 10 strains totaling 10(7) spores/can, and 4.3 Mrad if it is assumed that each can of beef contained 10(6) spores of a single most resistant strain and all of these spores were of identical resistances. However, an analysis of the data by extreme value statistics indicated with 90% confidence that the spore death rate was not a simple exponential but might be a shifted exponential (with an initial shoulder), Weibull, lognormal, or normal, with a "12D" equivalent of about 3.0 Mrad regardless of the initial spore density per can. There was an apparent antagonism between the irradiated type A and B strains in the cans. Some of the cans contained type B toxin but did not include type B viable cells. Other cans had a mixture of type A and B toxins, but a large number of these cans did not yield recoverable type B cells. However, type A viable cells could always be demonstrated in those cans containing type A toxin.

Animals↗
PubMedDate not supplied

Interaction of water activity and temperature on aflatoxin production by Aspergillus flavus and A. parasiticus in irradiated maize seeds.

The effects of aw (0.90, 0.95, 0.98) and temperature (25 degrees C, 30 degrees C, 35 degrees C) on aflatoxin production by Aspergillus flavus and Aspergillus parasiticus growing on irradiated maize seeds, were examined. Highest levels of aflatoxin were produced by A. parasitious at 25 degrees C and 0.98 aw and by A. flavus at 30 degrees C at 0.95 and 0.98 aw. At 0.90 aw toxin production was consistently low for both species at all temperatures. Temperature cycling of A. flavus between 25 degrees C and 35 degrees C each for 12 h resulted in higher aflatoxin synthesis than when incubated either at 25 degrees C or 35 degrees C.

Aflatoxins↗
PubMed2006

Gamma radiation sensitivity of Enterobacter sakazakii in dehydrated powdered infant formula.

The observed Enterobacter sakazakii D10-values for tryptic soy broth and dehydrated powdered infant formula were 0.27 +/- 0.05 and 0.76 +/- 0.08 kGy, respectively. A decrease of approximately 3 log in the dehydrated powdered infant formula was obtained by irradiation with 3.0 kGy or rehydration with hot water at 80 degrees C. No recoverable bacteria were found in the powdered infant formula irradiated at 5.0 kGy and stored, either before or after rehydration. A radiation dose of up to 5.0 kGy had no marked effect on the sensory properties of the dehydrated powdered infant formula after rehydration and heating. Gamma radiation could potentially be used to inactivate E. sakazakii in dehydrated powdered infant formula; however, nutritional studies need to be conducted before the use of radiation can be recommended.

Colony Count, Microbial↗