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Because of the unequal and, in some instances, low stability of different folate vitamers against extreme conditions the analytical determination of folate and the estimation of folate losses in food processing and preparation cause considerable difficulties. HPLC allows determination of the native folate derivative patterns. As the bioavailability of folates is influenced by a variety of factors and different methods were employed for assessing bioavailability there is a considerable inconsistency in the results of these studies. Folates labeled with radioactive or stable isotopes provide new approaches to metabolic and bioavailability studies.

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Levels of arsenic, lead and cadmium in cherries of harvest years 1911 to 1986, home-sterilized in glass jars, were determined by atomic absorption spectrometry. Concentrations of arsenic showed a decreasing trend during that period, presumably reflecting the discontinuation of the use of arsenic-containing pesticides. Unexpectedly, some of the older samples also contained more lead or more cadmium than more recent samples.

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The plant flavonol quercetin and the triazine herbicides atrazine, cyanazine, and gesamprim were examined individually and in combination for the induction of genotoxic effects. The sister chromatid exchange (SCE) assay and the gene mutation assay for 6-thioguanine resistance (HPRT) were carried out with Chinese hamster ovary (CHO) cells. Whereas no evidence of an increased SCE rate was found, the test substances caused a slightly increased mutation rate in the HPRT assay after metabolic activation with a subcellular liver enzyme preparation. Combination studies with two or three of the test substances did not result in higher mutation rates than those observed for the individual compounds tested singly.

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In the 1950s to '70s, food additives and contaminants were considered important risk factors for cancer and other chronic diseases. Opinion leaders like F. Eichholtz and W. Kollath in Germany and R. Carson and J.J. Delaney in the United States maintained that the exclusion of man-made chemicals from the food supply would decisively contribute to better health. In contrast to these views, world-wide scientific opinion now emphasizes the role of personal lifestyle, e.g., over-nutrition, unbalanced diets, smoking, and excessive alcohol consumption in the causation of chronic diseases. Dietary guidelines now recommended for the prevention of cancer are largely identical with those recommended for the prevention of cardiovascular disease. Indications are that oxidative damage to DNA contributes importantly to both these diseases. In research the role of antioxidants and other protective substances in foods receives as much attention today as man-made carcinogens received in the past. Media reporting and nutrition counseling have taken very little notice of these fundamental changes in scientific opinion.

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Generalizations about effects of irradiation may be misleading if the dose and commodities are not specified. Irradiation could be used for inhibition of sprouting, disinfestation, destruction of parasites in meat, to delay maturation of fruit and for pasteurization and sterilization. In some applications it could replace chemical sprout inhibitors, fumigants and chemical preservatives; in other cases it may have unique advantages e.g. in eradication of non-spore-forming pathogens in dry or frozen foods. Toxicological and nutritional evaluation has repeatedly confirmed the safety of irradiated foods. Effects on nutritional quality are frequently comparable with heat treatment and sometimes more conservative, particularly if oxygen is excluded. While food irradiation could be an alternative to chemical preservatives, misinformation has led to uncertainties as to its future.

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Natural (tritium, 14C, 40K, 226Ra) and man-made radionuclides (90Sr, 134Cs, 137Cs) were determined in soil (top 30 cm), vine leaves, grapes and wine in eight locations of the most important viticultural regions in the Federal Republic of Germany. The results obtained in 1983-1985 have been published previously. Part II of this study presents results obtained in 1986 and 1987, i.e. after the reactor accident at Chernobyl in the Soviet Union. The mean content of 137Cs before (after) Chernobyl was 4 (9) Bq/kg dry matter in soil, 0.07 (3) Bq/kg fresh matter in leaves, 0.02 (0.4) Bq/kg in grapes, and 0.008 (0.9) Bq/L in wine. As compared with 1986, distinctly lower levels were found in leaves, grapes and wine in 1987. In 1986 the content of 134Cs was about half that of 137Cs. Owing to its shorter half-life, 134Cs was below the detection limit in many of the 1987 samples. Transfer factors such as from soil to leaves and from soil to grapes for caesium agreed well in 1983-1985 and 1987, but showed considerable deviations in 1986, due to the ubiquitous contamination of the environment. Results of 90Sr determinations confirmed other reports showing this radionuclide to be a very minor contributor to the total radioactivity released at Chernobyl. No effect of the reactor accident on levels of the other radionuclides was detected.

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Radioactive contamination of wild-growing mushrooms collected in the Northern Black Forest and neighbouring Rhine Valley area has been monitored since the Chernobyl reactor accident. Cs-134, CS-137, Ag-100m and the natural nuclide K-40 were determined by gamma-spectrometry. Pooled data from all species and all locations showed a decrease in the radio-caesium levels from 1986 to 1988, both in mean values and maximum values. Samples of the same species collected at the same location exhibited large differences, although mixed samples rather than individual mushrooms were measured. Accumulation of caesium was observed particularly in Laccaria amethystina, Xerocomus badius, Xerocomus chrysenteron, Cantharellus tubaeformis, Laccaria laccata, and Russula ochroleuca, with maximum values of 3600 (1986), 2000 (1987), and 1200 (1988) Bq/kg of radiocaesium. A large number of species, among them Calocybe gambosa and Coprinus comatus, showed very small accumulations or no caesium. An accumulation of silver was found in Macrolepiota rhacodes and Agaricus arvensis, which contained a maximum of 11 Bq/kg Ag-110m.

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Radioactivity in total diet samples (1-day rations of adults) has been determined in the Federal Republic of Germany since 1960. Average intake of cesium-137 was 8.9 Bq per day and per person (Bq/d.p) in 1964, 0.15 in 1985, 4.2 in 1986, 7.2 in 1987, and 2.0 in 1988. Cesium-134, not measureable in pre-Chernobyl fallout, averaged 2.0 Bq/d.p in 1986, 3.0 in 1987, and 0.6 in 1988. Intake of strontium-90 was in the same range as in the years preceding the Chernobyl accident. It is estimated that the total effective equivalent dose for adults due to ingestion of Chernobyl-released radionuclides, including iodine-131, will be 0.14 +/- 0.08 mSv.

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The changes in nutrients during the germination of wheat, mung beans and chickpeas were investigated. Germination was performed under conditions commonly used in the household. The amount of water taken up during 4 days of germination varied from 159 g/100 g (chickpeas) to 450 g/100 g (mung beans). For all three seeds losses of dry matter and carbohydrates were observed. In wheat and mung beans, phytic acid was partially hydrolyzed. In mung beans, the total fat content decreased. Increases in the content of polyunsaturated fatty acids in wheat and of dietary fibre in wheat and mung beans were noted. At a constant level of crude protein, a measurable rise in limiting amino acids was observed in wheat and mung beans. Frequent watering during germination caused losses of Fe, between 9% and 21%, K (27% in chickpeas) and Cu (17% in chickpeas). Except for vitamin B6 in both legumes and vitamin B1 in chickpeas, accumulation of the vitamins under investigation (B1, B2, B6, C, E) was noted. Owing to these changes during germination, the nutritional value of the three seeds has been improved to various extents, most distinctly in wheat and least noticeably in chickpeas. Compared with other vegetables, sprouted seeds can be considered a valuable addition to the diet.

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From September to December of 1986, 85 samples of 34 species of wild mushrooms were collected, mostly in northern Baden and occasionally in neighboring areas. Cs-137, Cs-134, and the natural nuclide K-40 were determined by gamma-spectrometry. Samples from the Rhine Valley and the Kraichgau were generally much less contaminated than those from the Black Forest. With one exception, their radiocesium levels were below the Common Market limit of 600 Bq/kg. The exception was a sample of Laccaria amethystina with 1710 Bq/kg Cs-137 and 766 Bq/kg Cs-134. Relatively high levels were also found in Xerocomus badius, X. chrysenteron and Cantharellus tubaeformis. The hymenophore contained higher concentrations of radiocesium than the other parts of the body of the fruit. No correlation between the concentration of K-40 and that of the Cs nuclides was found. The ratio of Cs-137:Cs-134 was usually below 3 but reached the value of 11.8 in Piptoporus betulinus growing on birch wood. In this case, the substrate must have contained more radiocesium from the time before the Chernobyl reactor accident than from the time thereafter.

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As determined by in vivo studies using [1-14C] L-leucine and [1-14C] glycine, vitamin E deficiency in young rabbits caused a higher turnover rate of liver proteins and of plasma albumin and globulin fractions. This effect was most clearly and consistently observed in animals fed a diet containing 10 mg of the non-absorbable polymeric antioxidant Anoxomer per g of fat in the diet.

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Previous studies of metabolic changes in vitamin E-deficient animals were often difficult to interpret because the vitamin E-free, high PUFA diets used in such studies may have contained high levels of peroxides. Presumed effects of vitamin E deficiency could have been effects of peroxide consumption. Addition of the non-absorbable polymeric antioxidant Anoxomer to a semisynthetic vitamin E-free diet containing cod liver oil was found to suppress peroxide formation. Nevertheless, this diet produced necrotizing myopathy, characterized by high urinary creatine excretion, muscular weakness, and increased rate of incorporation of [1-14C] glycine into muscle proteins. These effects were prevented by vitamin E supplementation. The increased rate of muscle protein turnover is obviously the result of vitamin E deficiency, not the result of consumption of dietary peroxides.

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A pulverized mixture of Agaricus species known to accumulate cadmium, mixed 15:85 with standard rat diet, was fed to a group of growing rats. The mixture contained 3.87 micrograms Cd/g dry weight. A control group received the standard rat diet alone (0.08 microgram Cd/g). During the feeding period of 6 weeks the animals of both groups excreted about 90% of the ingested cadmium in the faeces. In comparison to the control group, the experimental group accumulated much more cadmium in liver, kidneys, and remaining carcass. While it is concluded that the bioavailability of cadmium contained in mushrooms is not less than that of cadmium contained in other feeds and foods, most mushroom species do not contain more cadmium than other vegetables. In humans the average cadmium intake from the total diet is considerably below the tolerable level. Generalized warnings against consumption of mushrooms are therefore not considered necessary.

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Beginning on the 25th day of life and for 2 weeks therafter Sprague-Dawley rats were fed a casein diet containing 10% of gum guar. The animals were given. 14C algal protein or 14C algal protein hydrolysate by stomach tube and the radioactivity in some tissues and tissue proteins was determined 3 h after the application. Radioactivity in blood and in respiratory CO2 was measured up to 3 h and 6 h, respectively, after the application. The results indicate no effect of gum guar on the utilization of the protein or of the amino acids of the protein hydrolysate.

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The protective effect of low temperatures during irradiation on vitamin B1 and E levels in foods is not abolished by subsequent storage or heating. Egg powder irradiated at 1 Mrad in the presence of air and stored for 4 months at ambient temperature lost 68% of its thiamin content when irradiated at 20 degrees C, 33% when irradiated at -30 degrees C. Sunflower oil irradiated at 3 Mrad in the presence of air and subsequently heated for 1 hour at 180 degrees C lost 98% of its alpha-tocopherol content when irradiated at 20 degrees C, 65% when irradiated at -30 degrees C. Exclusion of atmospheric oxygen by packaging under nitrogen reduced the loss of alpha-tocopherol in irradiated (0.1 Mrad) rolled oats after 8 months of storage from 56 to 5% and the loss of thiamin from 86 to 26%. Vacuum packaging was equally effective during the first 3 months and somewhat less effective during the following 5 months. Packaging under carbon dioxide showed no advantage over packaging in air. Sensory evaluation of rolled oats, raw or cooked, 1 and 3 months after irradiation with 0.1 Mrad indicated no significant quality difference between unirradiated and irradiated samples packaged under nitrogen.

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Vitamin A losses induced by 10 MeV electrons in cream cheese, calf liver sausage, pig liver, whole egg powder and margarine continued to increase during storage for 4--8 weeks in presence of air. Thus vitamin A loss in sausage irradiated with 5 Mrad was 22% on the day after irradiation, 61% after 4 weeks. Irradiation and storage at 0 degrees C instead of at ambient temperature reduced these losses considerably. Exclusion of air (vacuum, nitrogen) or irradiation on dry ice (approx. -80 degrees C) were even more effective in preventing destruction of vitamin A. After 4 weeks of storage, cream cheese irradiated at 5 Mrad had lost 60% when irradiated and stored in air at ambient temperature, 20% in nitrogen atmosphere, 5% in vacuum package, and 5% when irradiated on dry ice and stored at ambient temperature.

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The micronucleus test was used to study possible mutagenic effects of (1) Irradiated potatoes extracted (a) immediately and (b) after 24-h storage following irradiation; (2) Irradiated and unirradiated chlorogenic acid; and (3) Trenimon. It was observed that irradiated potatoes (groups 1 a, b) and chlorogenic acid (group 2) did not cause mutagenic effects in the bone-marrow cells of rats. The Trenimon group (group 3), which was used as the positive control group, did show significant mutagenic effects.

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