Critical review of supercritical carbon dioxide extraction of selected oil seeds

Supercritical carbon dioxide extraction, as a relatively new separation technique, can be used as a very efficient process in the production of essential oils and oleoresins from many of plant materials. The extracts from these materials are a good basis for the new pharmaceutical products and ingredients in the functional foods. This paper deals with supercritical carbon dioxide extraction of selected oil seeds which are of little interest in classical extraction in the food industry. In this article the process parameters in the supercritical carbon dioxide extraction, such as pressure, temperature, solvent flow rate, diameter of gound materials, and moisture of oil seed were presented for the following seeds: almond fruits, borage seed, corn germ, grape seed, evening primrose, hazelnut, linseed, pumpkin seed, walnut, and wheat germ. The values of investigated parameters in supercritical extraction were: pressure from 100 to 600 bar, temperature from 10 to 70oC, diameter of grinding material from 0.16 to 2.0 mm, solvent flow used from 0.06 to 30.0 kg/h, amount of oil in the feed from 10.0 to 74.0%, and moisture of oil seed from 1.1 to 7.5%. The yield and quality of the extracts of all the oil seeds as well as the possibility of their application in the pharmaceutical and food, industries were analyzed

Bestimmung von Chrom und seinen Spezies im Boden

Im Rahmen der vorliegenden Arbeit wurde ein Beitrag zur Speziation von Chrom geliefert, nachdem ein Verfahren auf Basis eines mikrowellenassistierten Aufschlusses zur Bestimmung von Gesamtchrom in umweltrelevanten Proben erarbeitet wurde. Hierbei wurde der mikrowellenbeheitzte Aufschluß in geschlossenen Gefäßen eingesetzt, und die nötigen Optimierungsschritte für den Aufschluß und der anschließenden Bestimmung mit der AAS oder ICP-OES in Ihrer Richtigkeit überprüft. Das Verfahren zur Bestimmung von Gesamtchrom wurde dazu für die Analyse von Standardreferenzmaterialien, nämlich der Bodenprobe BCR 141 und einer Flugaschenprobe BCR 176 eingesetzt. Nachdem nun ein Verfahren zur Bestimmung des Gesamtchroms in Bodenproben zur Verfügung stand, wurde ein Verfahren entwickelt mit dem das Adsorptionsverhalten der toxikologisch und biologisch unterschiedlich wirkenden Chromspezies im Boden studiert werden kann. Hierzu wurden Proben mit den Hauptbestandteilen von Böden, nämlich der Tonfraktion (Bentonit) und der Sandfraktion, selektiv mit den Cr-Spezies versetzt. Diese so erhaltenen Proben wurden dann auf Ihren Gesamtgehalt an Chrom und die Flüssigphasen auf die extrahierbaren Fraktionen der Cr-Spezies hin analysiert. Um den Grad der Adsorption der Spezies studieren zu können wurde im Rahmen dieser Arbeit ein neuartiges Verfahren erarbeitet mit der in Bodenextrakten Cr (III) und Cr (VI) innerhalb einer Analysenzeit von weniger als 2 min zuverlässig bestimmt werden können. Dazu wurde ein neuartiger Versuchsaufbau erstellt, in dem mittels einer ionenchromatographische Trennung der beiden Spezies von Chrom erfolgreich durchgeführt werden kann. Der Efluent aus der Säule wurde dann über eine Hydraulische Hochdruckzerstäubung (HHPN) zerstäubt und dann nach Desolvation einem ICP zugeführt und mittels OES detektiert. Die erhaltenen Ergebnisse wurden mit denen der Cr (VI) Bestimmung mittels Spektralphotometrie als unabhängige Methode verglichen und stimmten gut überein. Die durchgeführten Untersuchungen belegen, daß es gelungen ist ein leistungsfähiges Verfahren zur Bestimmung von Gesamtchrom aus dem Boden aber auch eine Bestimmung von Cr(III) und Cr (VI) in einem Extrakt der Böden zu entwickeln. Diese Methoden konnten bereits eingesetzt werden, um an den Modelsubstanzen Bentonit und Sand das Adsorptionsverhalten der einzelnen Cr-Spezies zu studieren. Abschließend wurde die Speziesbestimmung von Chrom für die Extrakte einer Bodenprobe durchgeführt und es konnten mit einer guten Wiederfindung im Vergleich zum DIN Verfahren das lösliche Cr (VI) bestimmt werden. So wurden in den Extrakten dieser Bodenprobe ein Gesamtgehalt von 327 + 8,1 µg/L Chrom bestimmt. Der Gehalt an toxikologisch bedenklichen Cr (VI) wurde nach dem DIN Verfahren mit 302 + 6,7 µg/L und nach dem hier entwickelten IC-ICP-OES Verfahren mit 306 + 7,4 µg/L bestimmt. Im Gegensatz zum DIN Verfahren kann aber auch mit dem neuen Verfahren der IC-ICP-OES simultan das Cr (III) erfasst werden, welches in dem Extrakt der Bodenprobe eine Konzentration von 28 + 3,4 µg/L aufwies und nach der Differenzberechnung nach DIN eine Konzentration von 25 µg/L aufwies. So zeigen sich hier die gute Einsatzmöglichkeiten des neuen Verfahrens, um innerhalb von zwei Minuten Extrakte von Bodenproben auf die einzelnen Chromspezies zu analysieren und so sehr schnell zuverlässige Aussagen über den Belastungsgrad von Bodenproben zu erhalten

Cavity-Enhanced Raman Spectroscopy in the Biosciences: In situ, Multicomponent and Isotope Selective Gas Measurements to Study Hydrogen Production and Consumption by Escherichia coli

Recently we introduced cavity-enhanced Raman spectroscopy (CERS) with optical feedback cw-diode lasers as a sensitive analytical tool. Here we report improvements made on the technique and its first application in the biosciences for in situ, multicomponent, and isotope selective gas measurements to study hydrogen production and consumption by Escherichia coli. Under anaerobic conditions, cultures grown on rich media supplemented with D-glucose or glycerol produce H2 and simultaneously consume some of it. By introducing D2 in the headspace, hydrogen production and consumption could be separated due to the distinct spectroscopic signatures of isotopomers. Different phases with distinctly different kinetic regimes of H2 and CO2 production and D2 consumption were identified. Some of the D2 consumed is converted back to H2 via H/D exchange with the solvent. HD was formed only as a minor component. This reflects either that H/D exchange at hydrogenase active sites is rapid compared to the rate of recombination, rapid recapture of HD occurs after the molecule is formed, or that the active sites where D2 oxidation and proton reduction occur are physically separated. Whereas in glucose supplemented cultures, addition of D2 led to an increase in H2 produced, while the yield of CO2 remained unchanged; with glycerol, addition of D2 led not only to increased yields of H2, but also significantly increased CO2 production, reflecting an impact on fermentation pathways. Addition of CO was found to completely inhibit H2 production and significantly reduce D2 oxidation, indicating at least some role for O2-tolerant Hyd-1 in D2 consumption

Remodeling of algal photosystem I through phosphorylation

Photosystem I (PSI) with its associated light-harvesting system is the most important generator of reducing power in photosynthesis. The PSI core complex is highly conserved, whereas peripheral subunits as well as light-harvesting proteins (LHCI) reveal a dynamic plasticity. Moreover, in green alga, PSI-LHCI complexes are found as monomers, dimers, and state transition complexes, where two LHCII trimers are associated. Herein, we show light-dependent phosphorylation of PSI subunits PsaG and PsaH as well as Lhca6. Potential consequences of the dynamic phosphorylation of PsaG and PsaH are structurally analyzed and discussed in regard to the formation of the monomeric, dimeric, and LHCII-associated PSI-LHCI complexes

Novel Insights Into N-Glycan Fucosylation and Core Xylosylation in C. reinhardtii

Chlamydomonas reinhardtii (C. reinhardtii) N-glycans carry plant typical beta 1,2-core xylose, alpha 1,3-fucose residues, as well as plant atypical terminal beta 1,4-xylose and methylated mannoses. In a recent study, XylT1A was shown to act as core xylosyltransferase, whereby its action was of importance for an inhibition of excessive Man1A dependent trimming. N-Glycans found in a XylT1A/Man1A double mutant carried core xylose residues, suggesting the existence of a second core xylosyltransferase in C. reinhardtii. To further elucidate enzymes important for N-glycosylation, novel single knockdown mutants of candidate genes involved in the N-glycosylation pathway were characterized. In addition, double, triple, and quadruple mutants affecting already known N-glycosylation pathway genes were generated. By characterizing N-glycan compositions of intact N-glycopeptides from these mutant strains by mass spectrometry, a candidate gene encoding for a second putative core xylosyltransferase (XylT1B) was identified. Additionally, the role of a putative fucosyltransferase was revealed. Mutant strains with knockdown of both xylosyltransferases and the fucosyltransferase resulted in the formation of N-glycans with strongly diminished core modifications. Thus, the mutant strains generated will pave the way for further investigations on how single N-glycan core epitopes modulate protein function in C. reinhardtii

Proteomics to go: Proteomatic enables the user-friendly creation of versatile MS/MS data evaluation workflows

We present Proteomatic, an operating system independent and user-friendly platform that enables the construction and execution of MS/MS data evaluation pipelines using free and commercial software. Required external programs such as for peptide identification are downloaded automatically in the case of free software. Due to a strict separation of functionality and presentation, and support for multiple scripting languages, new processing steps can be added easily

Tuning the Properties of Hydrogen-bonded Block Copolymer Worm Gels Prepared via Polymerization-Induced Self-Assembly

Polymerization-induced self-assembly (PISA) is exploited to design hydrogen-bonded poly(stearyl methacrylate)-poly(benzyl methacrylate) [PSMA-PBzMA] worm gels in n-dodecane. Using a carboxylic acid-based RAFT agent facilitates hydrogen bonding between neighboring worms to produce much stronger physical gels than those prepared using the analogous methyl ester-based RAFT agent. Moreover, tuning the proportion of these two types of end-groups on the PSMA chains enables the storage modulus (G’) of the 20% w/w worm gel to be tuned from ~4.5 kPa up to ~114 kPa. This is achieved via two complementary routes: (i) an in situ approach using binary mixtures of acid- and ester-capped PSMA stabilizer chains during PISA or (ii) a post-polymerization processing strategy using a thermally-induced worm-to-sphere transition to mix acid- and ester-functionalized spheres at 110 °C that fuse to form worms on cooling to 20°C. SAXS and rheology studies of these hydrogen-bonded worm gels provide detailed insights into their inter-worm interactions and physical behavior, respectively. In the case of the carboxylic acid-functionalized worms, SAXS provides direct evidence for additional inter-worm interactions, while rheological studies confirm both a significant reduction in critical gelation concentration (from approximately 10% w/w to 2-3% w/w) and a substantial increase in critical gelation temperature (from 41 °C to 92 °C). It is remarkable that a rather subtle change in the chemical structure results in such improvements in gel strength, gelation efficiency and gel cohesion

Photosystem I light-harvesting proteins regulate photosynthetic electron transfer and hydrogen production

Linear electron flow (LEF) and cyclic electron flow (CEF) compete for light-driven electrons transferred from the acceptor side of photosystem I (PSI). Under anoxic conditions, such highly reducing electrons also could be used for hydrogen (H2) production via electron transfer between ferredoxin and hydrogenase in the green alga Chlamydomonas reinhardtii. Partitioning between LEF and CEF is regulated through PROTON-GRADIENT REGULATION5 (PGR5). There is evidence that partitioning of electrons also could be mediated via PSI remodeling processes. This plasticity is linked to the dynamics of PSI-associated light-harvesting proteins (LHCAs) LHCA2 and LHCA9. These two unique light-harvesting proteins are distinct from all other LHCAs because they are loosely bound at the PSAL pole. Here, we investigated photosynthetic electron transfer and H2 production in single, double, and triple mutants deficient in PGR5, LHCA2, and LHCA9. Our data indicate that lhca2 and lhca9 mutants are efficient in photosynthetic electron transfer, that LHCA2 impacts the pgr5 phenotype, and that pgr5/lhca2 is a potent H2 photo-producer. In addition, pgr5/lhca2 and pgr5/lhca9 mutants displayed substantially different H2 photo-production kinetics. This indicates that the absence of LHCA2 or LHCA9 impacts H2 photo-production independently, despite both being attached at the PSAL pole, pointing to distinct regulatory capacities