Identification of a novel vitispirane precursor in Riesling wine

Glycoconjugated forms of diastereoisomeric 1-(3-hydroxybutyl)-6,6-dimethyl-2-methylene-3-cyclohexen-1-ols have been identified as new natural vitispirane precursors in Riesling wine. Model degradation studies carried out with synthetic references of the precursors showed the easy formation of isomeric vitispiranes at pH conditions of wine. Based on these results a hypothetic pathway for vitispiranes in Riesling wine is proposed.Identifizierung eines neuen Vitispiranvorläufers in RieslingweinZwei Diastereomere von 1-(3-Hydroxybutyl)-6,6-dimethyl-2-methylen-3-cyclohexen-1-ol wurden erstmals als Aglykone in Glykosidextrakten von Rieslingwein identifiziert. Modellreaktionen bei pH 3,2 lieferten die isomeren Vitispirane als Hauptabbauprodukte. Aufgrund dieser Ergebnisse wird ein erweitertes Modell zur Vitispiranbildung in Rieslingwein vorgestellt

Application of on-line coupled mass spectrometric techniques for the study of isomeric vitispiranes and their precursors of grapevine cv. Riesling

On-line coupled multidimensional gas chromatography - mass spectrometfy (MDGC-MS) in the column combination DB-Wax/2,6-di-O-methyl-3-O-pentyl-β-cyclo-dextrin allowed for the first time the determination of the enantiomeric composition of vitispiranes in Riesling wine. The order of elution was determined with the help of optically pure reference compounds. In the case of the (2R,5R)/(2S,5S)-enantiomers almost racemic proportions were determined, whereas in the case of the (2R,5S)/(2S,5R)-enantiomers the (2S,SR)-isomer prevailed. On-line coupled liquid chromatography - tandem mass spectrometry (LC-MS/MS) furthermore allowed the identification of the vitisprane-yielding precursor 3,4-dihydroxy-7,8-dihydro-β-ionol 3-O-β-D-glucopyranoside in Riesling wine and grapevine leaves

Cultivation and analysis of anthocyanin containing types of potatoes in organic farming regarding cultivability and additional health benefits

In a two year research project a representative spectrum of blue potato varieties were cultivated and tested in detail regarding disease infestation, yield potential and the influence of production systems (organic). Cultivation recommendations for blue potatoes could be deduced from this. Furthermore the varying anthocyanin content as well as the antioxidant capacity of the varieties used was analysed. Varieties with a particularly high content will undergo further tests to show the influence of the manner of preparation (boiling, steaming, frying) and determine their use for the processing industry. The combination of ecologically produced potatoes with „additional health benefits“ arouses the customers interest. The cultivation of high yield blue types can be an alternative to the cultivation of yellow fleshed high yield varieties in organic operating companies

Rapid isolation of malvidin 3-glucoside from red wine by high speed countercurrent chromatography (HSCCC)

Research Not

Isolation of the glucose ester of (E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid from Riesling wine

A glycosidic isolate of Riesling wine was separated with multilayer coil countercurrent chromatography (MLCCC). After acetylation and subsequent purification by high performance liquid chromatography (HPLC), the glucose ester of (E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoic acid (linalool-8-carboxylic acid) 1 was identified for the first time as natural wine constituent. The possible role of I as wine aroma precursor is discussed

Isolation of 2-ethyl-3-methylmaleimide N-β-D-glucopyranoside from Riesling wine

A glycosidic isolate of Riesling urine was separated with multilayer coil countercurrent chromatography (MLCCC). After acetylation and subsequent purification by high performance liquid chromatography (HPLC), the N-beta-D-glucopyranoside of 2-ethyl-3-methylmaleimide (3-ethyl-4-methyl-1H-pyrrole-2,5-dione) 2 was identified for the first time as natural wine constituent. The identification was carried out by mass spectrometry (EI-MS, DCI-MS) as well as nuclear magnetic resonance spectroscopy (H-1 NMR, 13C NMR, COSY, HMBC)

Isolation and structure of Pinotin A, a new anthocyanin derivative from Pinotage wine

Research Not

Antioxidants in white wine (cv. Riesling): I. Comparison of different testing methods for antioxidant activity

This paper provides a study on different testing methods for antioxidant activity. Four commonly used methods (LDL oxidation, TAS measurement, beta-carotene bleaching as well as a rapid screening test published by PRYOR et al. 1993) are compared on the basis of a set of model compounds. The differing results concerning the ranking order of the tested substances are discussed. Furthermore three methods which showed appropriate results were used in order to determine the antioxidant activity of Riesling wine fractions

Structural analysis of the architecture and in situ localization of the main S-layer complex in Deinococcus radiodurans

Bacterial surface layers are paracrystalline assemblies of proteins that provide the first line of defense against environmental shocks. Here, we report the 3D structure, in situ localization, and orientation of the S-layer deinoxanthin-binding complex (SDBC), a hetero-oligomeric assembly of proteins that in Deinococcus radiodurans represents the main S-layer unit. The SDBC is resolved at 11-Å resolution by single-particle analysis, while its in situ localization is determined by cryo-electron crystallography on intact cell-wall fragments leading to a projection map at 4.5-Å resolution. The SDBC exhibits a triangular base with three comma-shaped pores, and a stalk departing orthogonally from the center of the base and oriented toward the intracellular space. Combining state-of-the-art techniques, results show the organization of this S-layer and its connection within the underlying membranes, demonstrating the potential for applications from nanotechnologies to medicine

Characterisation of aroma-active compounds in commercial aged rums

The volatile compounds in commercial rums declared as aged 3, 7, 10, and 15 years were isolated by solvent extraction followed by solvent-assisted flavour evaporation and analysed by gas chromatography-olfactometry. According to the aroma extract dilution analysis, 19 potentially aroma-active compounds in the flavour dilution (FD) factor range of 8 to 1024 were found. Fifteen of them were present in at least one aged rum at FD factor≥128. Clear differences in the FD factors of these odourants between each of the aged rums suggested that they contributed to their unique sensory profiles