Congruent strategies for carbohydrate sequencing. 3. OSCAR: an algorithm for assigning oligosaccharide topology from MSn data

This is the third in a sequence of reports devoted to the development of congruent strategies for carbohydrate sequencing. Two previous reports outlined the strategies for observing structural detail from MSn data and introduced tools that compile, search, and compare fragment spectra in a bottom-up approach to oligosaccharide sequencing. In this third report, we introduce the operational details of an algorithm that we define as the Oligosaccharide Subtree Constraint Algorithm (OSCAR). This algorithm assimilates analyst-selected MSn ion fragmentation pathways into oligosaccharide topology (branching and linkage) using what may be considered a top-down sequencing strategy. Guided by a series of logical constraints, this de novo algorithm provides molecular topology without presumed biosynthetic constraints or external comparisons. In this introductory study, OSCAR is applied to a series of permethylated oligomers and isomeric glycans, and topologies are assigned in a few hundredths of a second.     

Krümmungsmessung an belasteten Platten nach dem Ligtenbergschen Moiré-Verfahren

Zusammenfassung Das Verfahren von F. K. Ligtenberg wurde derart abgewandelt, da? man es—nach kleinen Erg?nzungen— mit der üblichen Ausstattung eines spannungsoptischen Laboratoriums anwenden kann. Ferner wurden Auswertungsformeln für krummlinige Koordinaten entwickelt, ein zeichnerisches Verfahren zum unmittelbaren Bestimmen der Hauptkrümmungslinien aus den Moirélinien angegeben und das Aufl?sungsverm?gen des Verfahrens überschl?gig berechnet. Das abgewandelte Verfahren ist an Beispielen erprobt worden.     

Schutzsysteme für Verschraubungselemente in Kontakt mit Leichtmetall

Protective coating systems for fasteners in contact with light weight metals A review of the recent use of fasteners for light weight alloys in automotive car production is given. Mechanical design, materials selection and protective coating concepts for Magnesium- and Aluminum-alloys are presented. The specific problems caused by galvanic corrosion are discussed by the use of electrochemical data of the protective coating systems on fasteners for joining Magnesium. Experience from outdoor exposure in automotive applications up to date are considered.     

Contribution of peptides and polyphenols from olive water to acrylamide formation in sterilized table olives

To confirm the role of peptides as principal precursors of acrylamide formation in sterilized table olives, peptides from olive water were fractionated. After their partial fractionation by solid phase extraction (SPE) and ultrafiltration (<10,000 Da), respectively, small peptides from olive water were isolated by size-exclusion chromatography (SEC). In the fractions collected, peptides and polyphenolic compounds were determined colorimetrically, and acrylamide was quantitated by LC–MS/MS after heating of the samples. Subsequently, peptides were characterized by matrix-assisted laser desorption/ionization-tandem time of flight mass spectrometry (MALDI-TOF/TOF-MS), and polyphenols were analyzed by LC–MS in the respective fractions. Finally, peptides containing fractions were purified on a polymeric resin (Amberlite XAD 16HP) to remove unbound phenolic compounds by adsorption. The results of the different experiments performed in complete absence of free asparagine and reducing sugars strongly support small peptides bound to polyphenols to be the principal precursors of acrylamide in sterilized table olives.     

Evaluation of the effects of thermal treatments on color, polyphenol stability, enzyme activities and antioxidant capacities of innovative pasty celeriac (Apium graveolens L. var. rapaceum (Mill.) DC.) products

Initial heating was applied as the first processing step in the production of innovative pasty celeriac products. For this purpose, celeriac was converted into a paste and subsequently heated at 90 and 100 °C for 5–10 min. Alternatively, the fresh plant material was blanched prior to mincing. For the first time, phenolic compounds in celeriac were characterized by high-performance liquid chromatography coupled with mass spectrometry (LC–MSⁿ). Among the 14 phenolics detected, several caffeic, ferulic and quinic acid derivatives as well as malonylated and acetylated flavonoid derivatives were newly identified. Upon thermal treatment, the antioxidant capacities (TEAC assay) and the total phenolic contents remained virtually unchanged. The antioxidant capacities of heated samples determined by the FRAP assay were even higher than those of the unheated control. The contents of the main phenolic compound apiin decreased upon heat treatment, whereas the levels of the minor compounds malonylapiin A and B increased. Only by extended steam- and water-blanching at 100 °C, respectively, complete inactivation of peroxidase and polyphenol oxidase was achieved. The obtained celeriac products were characterized by their bright white color. Consequently, blanching is recommended as the initial operation in the processing of celeriac into novel pasty products.     

Stability of yellow-orange cactus pear (<Emphasis Type="Italic">Opuntia ficus-indica</Emphasis> [L.] Mill. cv. ‘Gialla’) betalains as affected by the juice matrix and selected food additives

The impact of added ascorbic, isoascorbic, and citric acid on heat stability of cactus pear betalains was investigated at pH 4 and 6, respectively. To assess the influence of cactus pear juice matrix compounds such as sugars, organic acids, amino acids, and pectic substances on pigment stability, juice and purified pigment preparations derived therefrom were assayed separately. Immediately after heating at 85 °C for 1 h and a 24 h cool storage period, betalain retention, betanin and proline-betaxanthin isomerisation as well as overall colour changes were determined. Pigment stability and colour characteristics depended on type and concentration of the respective additive as well as on pH conditions. Interestingly, the stabilising effects of the additives under investigation were less pronounced in matrix-free pigment preparations compared to juice samples. Maximum pigment retention amounting to 79% was obtained when 0.1% citric acid was added to the juice at pH 6. For the first time, formation of 2-decarboxy-betanin upon thermal treatment of yellow-orange cactus pear juice being more distinct at pH 4 as compared to pH 6 is reported.     

Optimisation of mild-acidic protein extraction from defatted sunflower (Helianthus annuus L.) meal

For protein isolation from defatted sunflower meal, mild-acidic extraction was investigated to minimise concomitant oxidation and polymerisation of phenolic compounds and their irreversible binding to proteins. Because of the impaired solubility of sunflower proteins at low pH, the potential of sodium chloride (NaCl) to improve protein extractability was firstly screened for pH 2–11. Increasing NaCl concentrations of the aqueous solvent (c_NaCl) up to 2.8 mol/L enhanced the relative protein yield to almost 80% at ambient temperature and pH 5.6–7.4. As to improved protein recovery at minimal interactions with phenolic acids, the concerted effects of pH (3.2–7.4), c_NaCl (1–3 mol/L), temperature (T, 15–45 °C), and meal-to-solvent ratio (MSR, 0.03 and 0.05 g/mL) on the protein concentration of the extract (c_PE) and the relative protein yield (RPY) were examined, using response surface methodology (RSM). Aside from the prevailing influence of pH value and salt concentration, elevated temperature slightly enhanced protein extraction, whereas MSR mainly influenced c_PE, but hardly RPY. Calculated models proved suitable for the evaluation of extraction processes and the prediction of optimum conditions in terms of high protein yields at the lowest pH possible. Extraction at pH 6.0 was shown to be an appropriate compromise yielding 76–83% of the meal protein, depending on the constraints given. With elevated NaCl concentrations compensating for unfavourable pH conditions, mild-acidic extraction was found to be suitable for the recovery of high-quality sunflower protein in terms of light-coloured protein isolates.     

Quantification of anthocyanins in black carrot extracts (<Emphasis Type="Italic">Daucus carota</Emphasis> ssp.<Emphasis Type="Italic"> sativus</Emphasis> var.<Emphasis Type="Italic"> atrorubens</Emphasis> Alef.) and evaluation of their color properties

Pigment composition of 15 black carrot cultivars (Daucus carota ssp. sativus var. atrorubens Alef.) was screened by HPLC-MS. Up to seven cyanidin glycosides, five of which were acylated with hydroxycinnamic and hydroxybenzoic acids, were identified and quantified in the roots by HPLC-DAD. Contents of individual compounds indicated great differences in the potential of anthocyanin accumulation both between different cultivars and carrots of the same cultivar. Total anthocyanin amounts ranged from 45.4 mg/kg dry matter to 17.4 g/kg dry matter. To the best of our knowledge, this is the first report on the quantification of individual anthocyanins in roots of different black carrot cultivars. The determination of color properties in the extracts under various pH conditions proved black carrot anthocyanins to be applicable as natural food colorants also for low-acid food commodities, whereas a considerable loss of color was noted under nearly neutral conditions. Additionally, relatively high saccharide contents were found in almost all cultivars which may be disadvantageous when coloring concentrates are produced from carrot roots.     

Atmospheric methane: trends and cycles of sources and sinks

For more than 20 years the global emissions and the lifetime of methane have probably been constant, so the buildup of methane in the atmosphere has been slowing down for as long. During this time, there have been periodic events occurring every seven to eight years, when global methane concentrations increased by some 10 ppb and later fell back, in some cases due to temporary increases of emissions from the northern tropics that spread to the global scale. These conclusions are derived from the accumulated global observations that now span 23 years and define the role of human activities in the recent cycle of atmospheric methane.