Target-Guided Isolation of Progenitors of 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) from Riesling Wine by High-Performance Countercurrent Chromatography.

High-performance countercurrent chromatography (HPCCC) was used for the target-guided isolation of precursors of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) from Riesling wine. In separated HPCCC fractions of an Amberlite® XAD®-2 extract obtained from a German Riesling, TDN-generating fractions were identified by the acid-catalyzed hydrolysis of the progenitors at pH 3.0 and subsequent HS-GC-MS/MS analysis. The presence of multiple TDN-generating precursors in Riesling wine could be confirmed. From polar HPCCC fractions (11-13 and 14-16), 3,4-dihydroxy-7,8-dihydro-ß-ionone 3-O-rutinoside and 3,4-dihydroxy-7,8-dihydro-ß-ionone 3-O-ß-d-glucopyranoside were isolated as major TDN-precursors at a sufficient amount for structure elucidation by NMR spectroscopic studies. In the medium polar HPCCC factions (27-35), enzymatic hydrolysis liberated the aglycones 3-hydroxy-ß-ionone and 3-hydroxy-TDN in minor amounts. In further less polar TDN-generation fractions (36-44 and 45-50), glycosidic progenitors were absent; instead, a minor TDN formation most likely from non-conjugated constituents was observed.

Enantiodifferentiation of 1,2-propanediol in various wines as phenylboronate ester with multidimensional gas chromatography-mass spectrometry.

Native concentrations and enantiomeric distribution of 1,2-propanediol in various wines were studied in order to evaluate its merits as a potential marker for aroma adulteration in wine. Heart-cut multidimensional gas chromatography coupled to mass spectrometry was applied to analyze 1,2-propanediol after salting-out of the polar phase, derivatization with phenyl boronic acid, and extraction with cyclohexane. The enantiomeric separation of the derivative was achieved with heptakis-(6-O-tert. butyl dimethylsilyl-2,3-di-O-acetyl)-ß-cyclodextrin as the chiral selector. In all authentic wines studied, 1,2-propanediol showed a high enantiomeric ratio in favor of the (R)-enantiomer, proving its potential as a marker for the adulteration with flavor extracts based on industrial 1,2-propandiol as solvent. Usually, concentrations varied between 15 and 100 mg/L. Higher values (up to 170 mg/L) were found in wines made with high amounts of dry berries. However, despite the higher concentrations of 1,2-propanediol in such wines, no apparent influence on the enantiomeric distribution could be detected. Graphical Abstract Detection of fraudulent aromatization of wines by enantiodifferentiation of 1,2-propanediol as its phenylboronate ester.

Allochromatium humboldtianum sp. nov., isolated from soft coastal sediments.

A novel purple sulfur bacterium, strain AX1YPE(T), was isolated from marine sediments sampled at 47 m depth in Callao Bay, Perú. Strain AX1YPE grew anaerobically, synthesizing bacteriochlorophyll a and carotenoid pigments of the spirilloxanthin series. Cells were Gram-stain-negative rods and actively motile by a polar flagellum. Strain AX1YPE was able to grow photolithoautotrophically with sulfide and thiosulfate as electron donors. This new phototrophic organism utilized ammonium salt, N2, urea and glutamate as nitrogen sources. Strain AX1YPE had a DNA base composition of 63.9 mol% G+C. Analysis of the 16S rRNA gene sequence indicated that strain AX1YPE clusters in a separate branch within the genus Allochromatium of the family Chromatiaceae. Strain AX1YPE showed 16S rRNA gene sequence similarities of 98.2% with Allochromatium vinosum DSM 180(T) and Allochromatium minutissimum DSM 1376(T), 98.1% with Allochromatium phaeobacterium JA144(T), 97.3% with Allochromatium renukae DSM 18713(T) and 96.8% with Allochromatium warmingiiDSM 173(T). DNA-DNA hybridization values to the type strains of its closest relatives, A. vinosum and A. minutissimum, were 59 and 64%, respectively. The predominant fatty acid of strain AX1YPE(T) was C18 : 1ω;7c and it notably possessed C20 : 1 as a minor component. PCR-based molecular typing (Box A1R and randomly amplified polymorphic DNA) produced a unique banding pattern for strain AX1YPE(T) in comparison with the type strains of A. vinosum and A. minutissimum. Based on data from this polyphasic taxonomic study, which also includes average nucleotide identity comparison of five concatenated housekeeping genes, strain AX1YPE(T) is considered to represent a novel species of the genus Allochromatium for which the name Allochromatiumhumboldtianum sp. nov. is proposed. The type strain is AX1YPE(T) ( = DSM 21881(T) = KCTC 15448(T)).

Symposium Introduction: Recent Progress and Current Challenges in Wine Analytical Sciences.

Oenology, behind the more visible social and convivial aspects associated with the consumption of wine and spirits, has great complexity due to the coexistence of countless different styles of artisanal products, linked to the diversity of places grapes are grown and wine is produced, and its global distribution. Premium wine is not a commodity. To scientifically support such complexity requires an extremely rigorous and diversified scientific expertise, capable of supporting the continuous improvement of processes and products that are developed, evaluated, and offered on international markets. Rigorous chemical and sensory analyses are essential to this continuous process of improvement, and for several decades now have regularly brought together a large community of researchers from multidisciplinary backgrounds to share, discuss, and harmonize their knowledge and experience of wines. The 12th edition of In Vino Analytica Scientia 2022 was held in Neustadt, Germany, in July 2022. The conference was attended by over 240 delegates, from 23 nationalities, who shared different aspects of wine and spirits research, with 9 key note lectures; 37 full talks; 36 short communications, and over 200 posters. This special issue is a collection of full papers from a selection of contributed oral presentations and posters presented at the conference.

Sensory relevance of seven aroma compounds involved in unintended but potentially fraudulent aromatization of wine due to aroma carryover.

Bottling regular wines following aromatized wines on the same filling lines bears the risk of unintentional aroma carryover, which has led to accusations of illegal aromatization. Obeying guidelines of good manufacturing practice, aroma carryover with no sensory relevance shall be considered as a technical unavoidable transfer having no legal consequences. To detect sensory relevance, odor activity values greater than one are proposed. Odor detection thresholds (OTs) were determined in water, model wine, and white wine for three lactones, α-ionone, ethyl 2-methylbutanoate, trans-cinnamaldehyde, and eugenol. Using different matrices OTs varied by factors of 2 for α-ionone and up to 23000 for ethyl 2-methylbutanoate. For α-ionone, being most prone for carryover, the three times higher OT of consumers did not trigger any preference for the aromatized wines, but rejection at 300 µg/L. Assessing α-ionone spiked wines by descriptive analysis, significant changes in sensory attributes only occurred at concentrations 10 times above OT.

Algoriphagus aquaeductus sp. nov., isolated from a freshwater pipe.

A Gram-staining-negative, aerobic to microaerophilic, rod-shaped, red-coloured bacterium, strain T4(T), was isolated from a freshwater pipe on Tenerife island. A polyphasic taxonomic study was performed in order to characterize the strain in detail. The isolate is surrounded by a slime capsule, occurs singly, in the form of short chains, or in aggregates, and exhibits catalase and oxidase activities. Growth was observed at 15-42 °C. Optimum growth occurred at pH 8 with mono- and disaccharides, followed by polysaccharides and deoxysaccharides, but the bacterium utilized only a restricted spectrum of alcohols, alditols, amides, amines, carboxylic acids and amino acids. Strain T4(T) tolerated concentrations of 0-4% (w/v) NaCl and contained MK-7 as predominant isoprenoid quinone as well as carotenoids, but lacked pigments of the flexirubin type. The predominant fatty acids were iso-C(15:0) (32.2%), summed feature 3 (C(16:1)ω6c and/or C(16:1)ω7c; 22.5%), and iso-C(17:0) 3-OH (7.9%). Major polar lipids were phosphatidylethanolamine, phospholipids, aminophospholipids and other lipids of unknown character. The DNA G+C content was approximately 41.8 mol%. The sequence of the 16S-rRNA gene assigned strain T4(T) to the CFB group, forming a coherent cluster with species of the genus Algoriphagus with the highest similarity of 98.8% to Algoriphagus aquatilis A8-7(T). DNA-DNA hybridization revealed 37.5% relatedness to strain A8-7(T). Based on morphological, physiological and molecular properties as well as on phylogenetic distinctiveness, strain T4(T) should be placed into the genus Algoriphagus as a novel species, for which the name Algoriphagus aquaeductus sp. nov. (type strain T4(T) =DSM 19759(T) =LMG 24398(T) =NCIMB 14399(T)) is proposed.

Monte Carlo analyses of the fusion neutron and gamma signals from the chromium self-powered detector.

To test the applicability of self-powered detectors (SPDs) for radiation monitoring in fusion reactor blankets, several irradiation tests have been undertaken with the ad hoc designed Cr-SPD, which presents the novelty of using chromium as the emitter material. This detector was exposed to an intense 60Co gamma-ray source, and to the 14 MeV neutrons produced by the D-T fusion reaction. Detailed analyses of the measured signals have been done here using a Monte Carlo modeling technique. We describe the simulations of the fusion neutron and gamma tests of the Cr-SPD, and compare their results with the experimental ones. Keeping in view the difficulty in computational reproduction of the sophisticated nuclear-electrical phenomena behind low-level SPD signals, our model is found to perform well, giving correct electrical polarities and orders of magnitude of the signals, as well as valuable insights into their different components. Our experience has highlighted the deficits and the needed improvements for the traditional SPD simulation techniques for prompt signal analyses.

Uptake and Release of Aroma Compounds by an Ethylene Propylene Diene Monomer Rubber Sealing Polymer: Investigating Aroma Carryover in a Model Wine System.

Aromatized wines and regular table wines are often filled on the same bottling line. Sealing polymers in the filling line absorb volatiles from aromatized wines and may migrate due to insufficient cleaning into the subsequently bottled regular wine. Unintentional carryover of volatiles may lead to accusation of illegal aromatization of wine. Absorption, cleaning efficacy, and migration of volatiles into ethylene propylene diene monomer rubber were investigated in a model system. Direct thermal desorption-gas chromatography-mass spectrometry analysis of seven aroma compounds monitored variation in the polymer (µg/g). Absorption of volatiles was mostly driven by their octanol/water partition coefficients. Cleaning of polymers removed 11 to 62% of the absorbed volatiles. Subsequent immersion of cleaned polymers into model wine revealed migration of 20 to 57% of the remaining volatiles. Sensory tests suggested the impact of transferred volatiles into subsequent model wine. For α-ionone, an odor activity value of 1.03 indicated a potential sensory impact.

Sanitization of Oak Barrels for Wine-A Review.

Oak barrels form an integral part of wine production, especially that of high-quality wines where they are implemented as fermentation and aging vessels. Insufficient cleaning and sanitization of barrels can result in microbial spoilage which may have a detrimental impact on wine quality. To date, no review has been published on the various sanitization methods for wine barrels. The objective of this review is to provide an overview of the sanitization methods used in wineries from conventional techniques like the use of sulfur dioxide and steam to alternative and new approaches using ozone and high-power ultrasound. The methods' efficacies are outlined in terms of their ability to eradicate spoilage microorganisms such as Brettanomyces and acetic or lactic acid bacteria. Furthermore, their advantages and drawbacks are described together with their influence on physicochemical properties of the wood. Finally, limitations in existing knowledge are discussed and areas that merit further research are identified.

Impact of Rootstock, Clonal Selection, and Berry Size of Vitis vinifera sp. Riesling on the Formation of TDN, Vitispiranes, and Other Volatile Compounds.

The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and biosynthetically related vitispirane (VS) are important contributors to the varietal aroma of Riesling wines and are released from glycosidically bound carotenoid breakdown products during bottle aging. TDN is appreciated by numerous winemakers, particularly in aged Riesling wines. Higher levels of TDN, however, are perceived as a "petrol" off-flavor, which is expected to increase due to ongoing climate change. Wines produced from the same Riesling clone, which was grafted on six different rootstocks, varied significantly throughout two vintages in respect to their concentrations of free and bound TDN and VS as well as other volatiles. Over three vintages, the same compounds differed significantly among wines made from eight Riesling clones grafted on the same rootstock. Genetically determined loose grape clusters favored the formation of TDN and yielded wines of stronger sensory petrol intensity. Berry size, however, had no relevant impact on TDN and VS formation.

A new moderately thermophilic and high sulfide tolerant biotype of Marichromatium gracile, isolated from tidal sediments of the German Wadden Sea: Marichromatium gracile biotype thermosulfidiphilum.

A purple sulfur bacterium, strain SW26, was isolated in pure culture from intertidal sediments from the Sylt-Rømø Basin, German Wadden Sea, sharing many properties with validated Marichromatium species, but differing significantly by possessing a plasmid, by tolerating up to 16mM sulfide, and up to 44 degrees C for growth. Strain SW26 has a DNA base composition of 68.3mol% G+C, a 16S rRNA gene sequence similarity of >99% to those of Marichromatium species, and shows the highest level of genomic relationship with Marichromatium gracile, despite its remarkably different phenotypic characters. Based upon high genomic similarity but different physiological properties of strain SW26 with respect to the type strain of M. gracile, a novel biotype, designated as M. gracile biotype thermosulfidiphilum is described.

Automated supervised learning pipeline for non-targeted GC-MS data analysis.

Non-targeted analysis is nowadays applied in many different domains of analytical chemistry such as metabolomics, environmental and food analysis. Conventional processing strategies for GC-MS data include baseline correction, feature detection, and retention time alignment before multivariate modeling. These techniques can be prone to errors and therefore time-consuming manual corrections are generally necessary. We introduce here a novel fully automated approach to non-targeted GC-MS data processing. This new approach avoids feature extraction and retention time alignment. Supervised machine learning on decomposed tensors of segmented chromatographic raw data signal is used to rank regions in the chromatograms contributing to differentiation between sample classes. The performance of this novel data analysis approach is demonstrated on three published datasets.

Synthesis of Deuterium-Labeled 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) and Quantitative Determination of TDN and Isomeric Vitispiranes in Riesling Wines by a Stable-Isotope-Dilution Assay.

The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-dilution assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from two wine competitions, and analysis was performed by gas chromatography-mass spectrometry with selected-ion monitoring (GC-SIM-MS) as well as selected-reaction monitoring (GC-SRM-MS).

Multi-omics and potential applications in wine production.

The wine microbiome - that is the microbial communities associated with the fermentation of must, is one of the most important factors in transforming grapes to wine, including flavour and aroma. Recent developments in high throughput sequencing and other 'omics methodologies are rapidly changing the level and complexity of information that we are able to extract from the wine microbiome. This will significantly enhance not only our understanding of which microbes are present at the various stages of the grapevine growth and winemaking process, but also improve our understanding of the complex interactions between microbes, the substrate and environment, ultimately shaping wine production. In this perspective we describe the role and future potential of such techniques in wine production, and highlight the potential challenges that will be simultaneously faced.

Taxonomic and Functional Characterization of the Microbial Community During Spontaneous in vitro Fermentation of Riesling Must.

Although there is an extensive tradition of research into the microbes that underlie the winemaking process, much remains to be learnt. We combined the high-throughput sequencing (HTS) tools of metabarcoding and metagenomics, to characterize how microbial communities of Riesling musts sampled at four different vineyards, and their subsequent spontaneously fermented derivatives, vary. We specifically explored community variation relating to three points: (i) how microbial communities vary by vineyard; (ii) how community biodiversity changes during alcoholic fermentation; and (iii) how microbial community varies between musts that successfully complete alcoholic fermentation and those that become 'stuck' in the process. Our metabarcoding data showed a general influence of microbial composition at the vineyard level. Two of the vineyards (4 and 5) had strikingly a change in the differential abundance of Metschnikowia. We therefore additionally performed shotgun metagenomic sequencing on a subset of the samples to provide preliminary insights into the potential relevance of this observation, and used the data to both investigate functional potential and reconstruct draft genomes (bins). At these two vineyards, we also observed an increase in non-Saccharomycetaceae fungal functions, and a decrease in bacterial functions during the early fermentation stage. The binning results yielded 11 coherent bins, with both vineyards sharing the yeast bins Hanseniaspora and Saccharomyces. Read recruitment and functional analysis of this data revealed that during fermentation, a high abundance of Metschnikowia might serve as a biocontrol agent against bacteria, via a putative iron depletion pathway, and this in turn could help Saccharomyces dominate the fermentation. During alcoholic fermentation, we observed a general decrease in biodiversity in both the metabarcoding and metagenomic data. Unexpected Micrococcus behavior was observed in vineyard 4 according to metagenomic analyses based on reference-based read mapping. Analysis of open reading frames using these data showed an increase of functions assigned to class Actinobacteria in the end of fermentation. Therefore, we hypothesize that bacteria might sit-and-wait until Saccharomyces activity slows down. Complementary approaches to annotation instead of relying a single database provide more coherent information true species. Lastly, our metabarcoding data enabled us to identify a relationship between stuck fermentations and Starmerella abundance. Given that robust chemical analysis indicated that although the stuck samples contained residual glucose, all fructose had been consumed, we hypothesize that this was because fructophilic Starmerella, rather than Saccharomyces, dominated these fermentations. Overall, our results showcase the different ways in which metagenomic analyses can improve our understanding of the wine alcoholic fermentation process.

Analysis of aldehydes via headspace SPME with on-fiber derivatization to their O-(2,3,4,5,6-pentafluorobenzyl)oxime derivatives and comprehensive 2D-GC-MS.

A method for the analysis of the homologous series of alkanals, (E)-2-alkenals, and (E,E)-2,4-alkadienals is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Oxime derivatives formed on the fiber are desorbed in the gas chromatographic injector and analyzed by comprehensive 2-D GC coupled to quadrupole MS (GC x GC-qMS). Selecting specific fragment ions within the electron impact mass spectra of the oxime derivatives provides a suitable method for the target analysis of these aldehyde classes, which furthermore benefits from the increased separation efficiency by GC x GC. The analysis of higher molecular weight aldehydes is described in wine and grape seed oil as examples. Quantification of the aldehydes utilizes a stable isotope dilution analysis (SIDA) assay with octan-d(16)-al as isotopomeric internal standard. Besides the selectivity and sensitivity of aldehyde analysis using PFBHA derivatives, critical aspects on background level contamination and repeatability of the sample preparation method are discussed. Optimization of GC x GC-qMS parameters allowed a considerable saving of the cryogenic medium, involving additional (unmodulated) conditioning runs, rendering the method more amenable to routine analysis.

Light scattering by a nanoparticle and a dipole placed near a dielectric surface covered by a thin metallic film.

On the basis of Maxwell's equations a light scattering system of axial symmetry is considered, which consists of a nanoparticle, a dipole and a metal film (covering a dielectric support). Nanoparticle (NP) and dipole are situated on an axis of symmetry and the dipole is oriented along the axis and placed between film and nanoparticle. The field enhancement factor F and dipole energy flux D are calculated by the Green's function method: the initial system of Maxwell's equations is reduced to a system of boundary integral equations, and solutions are obtained by the boundary element method. Illumination of the scattering system by a radially polarized Bessel light beam causes a field enhancement in the vicinity of the film surface. The metallic NP closely placed at the film surface acts as nano-antenna. Surface plasmons excited in the particle and film convert the incident propagating EM field into non-propagating evanescent near-field. Then the field is confined and strongly enhanced in a particle/film gap. The enhancement of Raman radiation depends on many factors: size and shape of NP, permittivities of all materials, light wavelength, film thickness, angle of light beam, and - very strongly - on the gap distance. The field enhancement in a gap ~1 nm can be 10(3) and more and the Raman radiation enhancement factor can reach huge values ~10(10)-10(12). Whereas for small nanoparticles the field enhancement factor F and the dipole energy flux D do not depend on the direction of the exciting beam and on the angle of emission, a strong influence is found for extended particles. This influence is plausibly explained by a larger overlap between the electric field of the exciting beam or the emitted radiation field with the near field distribution of the nanoparticle leading to higher F and D values, respectively.

Rationale for Haze Formation after Carboxymethyl Cellulose (CMC) Addition to Red Wine.

The aim of this study was to identify the source of haze formation in red wine after the addition of carboxymethyl cellulose (CMC) and to characterize the dynamics of precipitation. Ninety commercial wines representing eight grape varieties were collected, tested with two commercial CMC products, and analyzed for susceptibility to haze formation. Seventy-four of these wines showed a precipitation within 14 days independent of the CMC product used. The precipitates of four representative samples were further analyzed for elemental composition (CHNS analysis) and solubility under different conditions to determine the nature of the solids. All of the precipitates were composed of approximately 50% proteins and 50% CMC and polyphenols. It was determined that the interactions between CMC and bovine serum albumin are pH dependent in wine-like model solution. Furthermore, it was found that the color loss associated with CMC additions required the presence of proteins and cannot be observed with CMC and anthocyanins alone.

In vitro and in vivo sulfate reduction in the gut contents of the termite Mastotermes darwiniensis and the rose-chafer Pachnoda marginata.

Sulfate-reducing bacteria (SRB) from termites have been assigned to the genus Desulfovibrio. Desulfovibrio intestinalis lives in the gut of the Australian termite Mastotermes darwiniensis. For the first time we were able to enrich and identify a sulfate-reducing bacterium from the gut of the rose-chafer Pachnoda marginata, which showed the highest 16S rDNA sequence identity (93%) to Desulfovibrio intestinalis and Desulfovibrio strain STL1. Compared to Mastotermes darwiniensis (1x10(7) cells of SRB per ml gut contents), sulfate-reducing bacteria occurred in higher numbers in the gut contents of Pachnoda marginata reaching cell titers of up to 2x10(8) cells per ml gut contents. In vitro sulfate reduction rates were determined with SRB from the gut contents of the termite Mastotermes darwiniensis and the beetle Pachnoda marginata. Due to the higher cell titer, the sulfate reduction rate of Pachnoda marginata was 10(4) nmolxh-1xml-1 and therefore, 21 times higher than that of Mastotermes darwiniensis. In addition, we detected in vivo sulfate reduction in Mastotermes darwiniensis, which indicates that sulfate reducers play an active role in the sulfur metabolism in the termite gut.

Dimethyl sulphoxide reduction with reduced sulphur compounds as electron donors by anoxygenic phototrophic bacteria.

The marine purple non-sulphur bacterium Rhodovulum euryhalinum strain DSM 4868 reduced dimethyl sulphoxide (DMSO) to dimethyl sulphide (DMS) chemotrophically with sulphide as electron donor. The oxidation of sulphide was correlated with the formation of polysulphides. R. euryhalinum reduced DMSO phototrophically with sulphide as well, but the amount of DMSO reduced in relation to sulphide oxidized was lower. The marine green sulphur bacterium Chlorobium vibrioforme strain DSM 8327 reduced DMSO to DMS phototrophically with sulphide and thiosulphate as electron donors. The extent of DMSO reduction was much less in the dark. Eight strains of purple sulphur bacteria - marine, brackish water and freshwater isolates - and another marine green sulphur bacterium showed a very weak capacity for DMSO reduction with sulphide or thiosulphate as electron donors in the light and dark, respectively.