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Ostertag E Becker T Ammon J Bauer-Aymanns H Schrenk D 《Journal of agricultural and food chemistry》2002,50(9):2565-2570
Furocoumarins represent a family of natural food constituents with phototoxic and photomutagenic properties. They are found mainly in plants belonging to the Rutaceae and Umbilliferae such as celery, carrots, and parsnips. Parsnips (Pastinaca sativa L.) have become more and more popular as a vegetable, e.g., as a constituent of or ingredient in baby food. Previous work has shown that microbial infection of parsnip roots can result in a dramatic increase in furocoumarin levels. In this study, freshly harvested parsnips were stored as whole roots, pieces (cubes), or homogenate at +4 degrees C or -18 degrees C over various time periods under standard conditions. It was found that furocoumarin concentrations (sum of five furocoumarins: angelicin, isopimpinellin, 5-methoxypsoralen, 8-methoxypsoralen, and psoralen) in freshly harvested parsnips, analyzed by HPLC after extraction with diethyl ether and sequential solid phase (reversed-phase and silica) extraction, was generally lower than 2.5 mg/kg, and storage of parsnips in any form investigated at -18 degrees C over up to 50 days did not lead to a marked increase in furocoumarin levels. In contrast, storage of whole parsnips, but not of cubes or homogenate, at +4 degrees C resulted in a marked biphasic increase of furocoumarin concentrations after 7 and 38 days of storage up to levels of about 40 mg/kg. A dramatic increase in furocoumarin concentrations up to 566 mg/kg was observed when whole parsnips obtained from the market were kept at room temperature over 53 days, resulting in a visible microbial (mold) infection. Baby food products from the German market containing parsnips as an ingredient or constituent showed furocoumarin levels < or =0.41 mg/kg, suggesting that properly stored roots/preparations have been used. It is recommended that, after harvesting, parsnips be kept at -18 degrees C or under other conditions that prevent microbial infections. 相似文献
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Seasonal nitrate content in, and nitrate leaching from, agricultural soils of Baden-Wuerttemberg The behavior of soil nitrate was investigated at five field locations in the State of Baden-Wuerttemberg between 1984 and 1987. It was found that the amount of nitrate in the upper 90 cm of soil was not a constant, but fluctuated throughout the year with maxima in the spring and in the fall. Additionally, it was found that the amount of nitrate leaching during winter (from November through April) was correlated to, but not identical with the mineral nitrogen content of the previous fall. It further appeared that nitrate leaching in light sandy soils is mainly a mixing process, whereas in heavy soils it seems to be more a miscible displacement phenomenon. 相似文献
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AL. Polizu Hildegard Greger Al. V. Alexandri 《Plant foods for human nutrition (Dordrecht, Netherlands)》1971,20(3):215-220
Summary The paper deals with studies on the dynamics of Carbaryl residue loss on apples, plums and peaches.The initial toxicant deposit ranges between 8 and 13 ppm on peaches, 2, 3 and 3, 4 ppm on apples and up to 1.5 ppm on plums. According to the dynamics of Carbaryl residue loss on fruit results a rest period of 2 days for plums, 7 days for apples and 21 days for peaches, on admitting a 2 ppm tolerance.
Presented at the Congress of Chemistry in Agriculture, Bratislava, Sept. 1969. 相似文献
Zusammenfassung Unter Berücksichtigung der Witterungsbedingungen wurde die Geschwindigkeit des Abbaus von Carbaryl-Rückständen bei Äpfeln, Pflaumen und Pfirsichen untersucht. Die anfängliche Höhe der Rückstände betrug bei Pfirsichen zwischen 8 und 13 ppm, bei Äpfeln 2,3 und 3,4 ppm und bei Pflaumen bis zu 1,5 ppm. Wird eine Toleranz von 2 ppm zugrundegelegt, ergibt sich entsprechend der Abbau-Geschwindigkeit von Carbaryl bei Früchten eine Wartezeit von 2 Tagen bei Pflaumen, 7 Tagen bei Äpfeln und 21 Tagen bei Pfirsichen.
Resume On présente de données sur la dynamique de la dégradation des résidus de Carbaryl sur pommes, prunes et pêches. Le résidu initial atteint 8–13 ppm chez les pêches, 2,3–3,4 ppm chez les pommes et 1,5 ppm chez les prunes.De cette dynamique de la dégradation des résidue sur fruits il résulte que pour les prunes l'intervalle de pause de deur jours, pour les pommes de 7 jours et pour les pêches de 25 jours dans les conditions climatiques de Roumanie.
Presented at the Congress of Chemistry in Agriculture, Bratislava, Sept. 1969. 相似文献
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Kerstin Scherr Hildegard Aichberger Rudolf Braun Andreas Paul Loibner 《European Journal of Soil Biology》2007,43(5-6):341
Various interactions occurring between organic chemicals and soil constituents participate in the determination of the fate of these pollutants, including their biodegradability. These relations need to be characterized in order to design and successfully implement a bioremediation application. In the present study, biodegradation of spiked and aged crude oil contamination in two dissimilar soils was related to their composition. GC-FID analysis of bulk soil samples as well as sand- and <63 μm fractions showed considerable differences in contaminant distribution and degradation behavior within these fractions. Whereas a freshly spiked silty soil showed reasonable degradation (51%), degradation was not significant after ageing. By contrast, a sandy soil was degraded by 25% (recently contaminated) and 19% (aged). Biodegradation occurred in the fine fraction only, with a comparably high content of organic carbon whereas hydrocarbon concentration remained constant in the sand fraction. This was correlated with sorption to the fine fraction where hydrocarbon concentrations were higher by over an order of magnitude compared to the sand fraction. Soil composition, biology and chemistry exert a pronounced influence on microbial degradation in respect to (i) contaminant availability and (ii) the structure and density of the microbial community. 相似文献
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