Elektronenspinresonanz-spektroskopische Untersuchungen an frischen Früchten

This paper describes the development of a method for the identification of irradiated fresh fruits by measurement of the e.p.r. spectra of pips, kernels or stones. Measurement parameters were optimized and the irradiation specific spectrum was assigned to a cellulose radical by comparison with the e.p.r. spectrum of pure cellulose. Several fruits especially different varieties of strawberries were examined giving the following results: Detectable minimum doses were between 0.4 kGy and 0.9 kGy and the intensity of the irradiation specific signals was found to be linear up to doses of 11 kGy. The lifetime of the specific radicals (at room temperature and at deep freezing temperatures) was long enough compared to the storage time of fresh fruits. Additional information about the nature of the unspecific central signal was gained measuring the samples which were stored at different temperatures. The main conclusion of this study is that the e.p.r. method seemes to be well suited for the use in routine control and should be tested in an intercomparison to establish a routine method for the identification of irradiated fresh fruits.     

<Emphasis Type="Italic">Chromohalobacter beijerinckii</Emphasis>: a psychrophilic,extremely halotolerant and enzymatically active microbe from salted food with the capacity for biogenic amine production

The species Chromohalobacter beijerinckii comb. nov. was recently proposed in order to accommodate strain Pseudomonas beijerinckii Hof 1935, which was found in salted beans, and a novel isolate, strain 3b, which was obtained from salted herrings of the Baltic sea. The species is psychrophilic, growing from 5 to 42 °C and highly salt-tolerant, growing between 0.5 and 25% NaCl. Of interest to food microbiology are several properties, which are described here, such as the enzymatic activity of Ch. beijerinckii strain 3b against fish protein, cod liver oil and butter. In addition, the strain possesses decarboxylases of lysine, tyrosine and histidine and can thus be a producer of biogenic amines, mainly histamine and tyramine. In media containing 10% NaCl, Ch. beijerinckii strain 3b is resistant to the antibiotics bacitracin, chloramphenicol, streptomycin, tetracycline and novobiocin. The potential impact of these properties, especially of the biogenic amine content in salted food, which were not known so far from other species of the genus Chromohalobacter, is discussed.     

Thermal energy storage for direct steam generation

Parabolic trough power plants with direct steam generation are a promising option for future cost reduction in comparison to the SEGS type technology. These new solar thermal power plants require innovative storage concepts, where the two-phase heat transfer fluid poses a major challenge. A three-part storage system is proposed where a phase change material (PCM) storage will be deployed for the two-phase evaporation, while concrete storage will be used for storing sensible heat, i.e. for preheating of water and superheating of steam. A storage system with a total storage capacity of approx. 1 MW h is described, combining a PCM module and a concrete module. The storage modules have been constructed for testing in a DSG-test facility specially erected at a conventional power plant of Endesa in Carboneras (Spain). Commissioning of the storage system started in May 2010; testing under real steam conditions around 100 bar will begin in August 2010.     

Chemical composition and biological activity of Citrus jambhiri Lush

The fresh peel of Citrus jambhiri was extracted with aqueous methanol and the residue was fractionated using light petroleum, chloroform and ethyl acetate. The constituents of the extracts were separated by column chromatography employing solvents of different polarity. The chemical structure of the isolated compounds was then identified by MS and NMR. Column chromatography of the petroleum fraction resulted in the isolation of nobiletin, 5-O-demethylnobiletin, tangeretin, 5-hydroxy-3,6,7,8,3′,4′-hexamethoxyflavone, 3,5,6,7,8,3′,4′-heptamethoxyflavone, and a mixture of β-sitosterol and stigmasterol. The chloroform fraction afforded 6-demethoxynobiletin, 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone, limonin and nomilin. The flavonoid glycosides naringin, hesperidin and neohesperidin were isolated from the ethyl acetate fraction. The chemical structure of the isolated compounds was established by MS and NMR (APT, COSY, HSQC, HMBC, and NOESY). LC–ESI-MS analysis of the ethyl acetate fraction afforded eight flavonoid glycosides, while the dichloromethane fraction of the defatted seeds contained seven limonoid aglycones. The chloroform fraction exerted the strongest DPPH^∗ free radical scavenging activity in comparison to other fractions. The petroleum fraction showed a significant inhibition of lipoxygenase indicating an anti-inflammatory action (IC₅₀ 29 ± 1 μg/mL). Some of the isolated polymethoxyflavones exhibited strong cytotoxicity against COS7, HeLa and Caco-2 cell lines.