In berry distribution and extraction of thiol precursors in Gew\ufcrztraminer.

The so-called varietal thiols are an interesting technological class of compounds that contributes to the "tropical" notes of wine. The factors governing the formation of their precursors and the conversion to the corresponding free forms are still discussed (Thibon et al. 2016) but, technologically speaking, the precursor availability is a prerequisite. Several data are present in the literature regarding Sauvignon Blanc (SB), while fewer deal with Gew\ufcrztraminer (GWT; Dubordieu and Tominaga 2009; Roland 2010a & b; Concejero et al., 2014), a variety native to Tramin, in South-Tyrol (Italy). For this reason, we investigated the concentration of 3-S-glutathionylhexan-1-ol (GSH-3MH) and 3-S-cysteinylhexan-1-ol (Cys-3MH) in GWT as regards: (1) the distribution between marks and juice in samples processed at a semi-industrial scale, in comparison with SB samples having similar \ub0Brix and pressing yield; (2) the effect of pre-fermentation skin-contact protocols, also used along with commercial enzymes to favour extractions from skin; (3) the fractioning during pressing on industrial-scale. Thiol precursors were analysed according to Larcher et al. (2013). GWT skins are characterised by a higher content in precursors compared to SB\u2019s at the same pressing yield, while this difference is turned upside down in juice. Pre-fermentation skin-contact significantly increased thiol precursors' concentration while the impact of the enzymes was not significant. Around 30% of total precursors are contained in the pressing fraction corresponding to the final 5% of the juice

Determining the Levels of Volatile Organic Pollutants in Urban Air Using a Gas Chromatography-Mass Spectrometry Method

The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B), toluene (T), ethyl benzene (E), and o-, m-, p-xylenes (X). Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7–60 μg/m3 (B), 13–90 μg/m3 (T), 7–50 μg/m3 (E), 10–70 μg/m3 (X-m,p), and 20–130 μg/m3 (X-o). The limits of quantitation/detection of the method LOQ/LOD are of 10/5 μg/m3 (Xo), 5/3 μg/m3 (B, E, X-m,p), and of 3/1 μg/m3 (T), respectively

Varietal thiol precursors in Gew\ufcrztraminer: effect of clone and grape ripening.

Much research has been carried out since the discovery of glutathionyl- (GSH-) and cysteinyl (Cys-) precursors of 3-mercaptohexan-1-ol (3MH) in grapes and juices (Tominaga et al.,1998; Peyrot des Gachons et al., 2002) in order to understand the origin of these precursors and optimize the technological options useful to liberate and maintain the free forms and the related fermentative compounds characterised by interesting tropical, passion fruit and grapefruit-like aroma. As few data are available about the role of these precursors in the case of Gew\ufcrztraminer (GWT; Roland Dubordieu and Tominaga 2009; Roland et al., 2010a & b; Concejero et al., 2014), an international variety native to Tramin (South-Tyrol, Italy) we investigated the effect of clone and ripening in grape samples of GWT grown in Trentino (Italy). The juices of 7 GWT clones - ISMA-AVIT 904, 906, 916, 918 and 920R, as well as LB14 and 1101 - grown in 4 plots and harvested at the technological ripeness allowed by the very hot 2015 vintage were analysed. Moreover, GWT grapes from 6 different non-clonal vineyards sited at a altitude between 120 and 525 m a.s.l. in Trentino were analysed during the last month before harvest. Thiol precursors were measured using an UHPLC approach with triple quadrupole mass detection according Larcher et al., (2013). Significant differences were found between clones as regards thiol precursors concentration in 2015 grape, the 906 and 920R clones showing a higher molar concentration of the sum of GSH-3MH and Cys-3MH compared to 916. A clear and statistically significant increasing trend during ripening was observed for the cited precursors, confirming for GWT previous results observed by Kobayashi et al (2010) for Koshu

Ethyl carbamate formation in sub-optimal wine storage conditions and influence of the yeast starter

Aim: To evaluate the potential risk of ethyl carbamate (EC) formation in wine by studying its production kinetics at suboptimal storage temperatures.Methods and results: The kinetics of EC formation was investigated in 60 white wines obtained from 6 varietal juices fermented with 10 yeast strains. The wines were analysed for their urea content at bottling, then EC formation was monitored during in-bottle storage at &lt; 12 °C for 150 days followed by 152 days at 40 °C. Storage at &lt; 12 °C had no effect on EC formation, regardless of initial urea content ; however, at 40 °C we found a positive correlation between initial urea content and final EC content.Conclusion: Urea content higher than 20 mg/L in wine kept at 40 °C can produce from 15 up to 30 μg/L EC in less than 5 days. Two yeast strains, La Claire SP665 and Maurivin Platinum, minimised the urea in wine, reducing the risk of EC formation.Significance and impact of the study: The temperatures used in this study can be accidentally - but easily - reached during suboptimal wine storage and shipping, and in the presence of substantial amounts of urea, the EC level can exceed the warning levels established by some countries in just a few days. The paper confirms the importance of minimising urea production in wine and controlling temperature during storage and shipping.</p

Analysis and assessment of urban atmospheric concentration of volatile pollutants

A method is presented, based on coupled gas chromatography-mass spectrometry GC-MS, to determine the atmospheric concentrations of benzene, toluene, ethyl benzene and o-, m-, p-xylenes mainly originating from the exhaust gas of internal combustion engines. Subsequent to preconcentration on active charcoal, the air contaminants were desorbed in dichloromethane, and perdeuterated benzene C6D6 was added as internal standard. The extract solutions were analyzed by GC-MS in the selected ion monitoring mode

Sampling and Identification of volatile and particulate air contaminants generated by intense road traffic in an urban area

A case study of urban air quality assessment was carried along a heavily circulated road, aiming to assess the impact of heavy vehicles traffic on the air quality on adjacent streets. A simple method was used for the collection of volatiles from air, in charcoal filled tubes. The analytes were desorbed in an organic solvent, then separated on a capillary column. The concentration of volatile organic atmospheric contaminants mainly originating from the exhaust gas of internal combustion engines, were then determined by using GC/MS quantitative analysis methods. Particulate matter concentrations in the air along the monitored street, were determined in 9 sampling sites, using a portable detector, and by applying the short time sampling methodology

Investigations of the effects of ultrasound on thiol precursors of grapes.

Gli ultrasuoni di potenza e ad alta amplitudine sono stati testati nelle fasi di macerazione prefermentativa delle uve bianche per studiare il possibile effetto sui precursori di sostanze tioliche. In particolare la ricerca si è concentrata sui precursori del 3-mercaptohexan-1-olo (3MH) e del 4-mercapto-4-methyl-pentan-2-one (4MMP) legati a glutathione (GSH) e cisteina (Cys). I trattamenti realizzati hanno confermato l’effetto estraente degli ultrasuoni che determinano una significativa estrazione di composti fenolici dalle bucce, nei brevi tempi di trattamento applicati (3 e 5 min), rispetto al testimone non trattato. Tuttavia la concentrazione dei principali precursori tiolici non cambia oppure subisce una importante diminuzione nel caso del 3-S-glutathionyl mercaptohexan-1-olo che decresce in modo significativo dopo 5 minuti di trattamento. Considerato il positivo effetto estraente degli ultrasuoni sulle bucce, è ipotizzabile un effetto diretto di interazione tra gli ultrasuoni con le molecole dei precursori tiolici. Per verificare tale ipotesi il trattamento è stato applicato su soluzioni modello aggiunte dei precursori del 3MH e del 4MMP. Le concentrazioni medie (n=5) dei precursori associati al GSH risultano significativamente diminuite dopo il trattamento (~-22% e ~18% per GSH-3MH e GSH-4MMP), mentre nel caso dei composti legati alla cisteina la diminuzione risulta meno importante ( ~-6% ~-8% per Cys-3MH e Cys-4MMP). La successive analisi dei tioli liberi hanno confermato l’effetto degradativo degli ultrasuoni sui precursori con liberazione significativa dei tioli liberi 3MH e 4MMP. Questi risultati avvalorano esperienze realizzate a livello di cantina su Sauvignon dove sono stati riscontrati incrementi dei tioli totali e miglioramenti sensoriali sui vini ottenuti da trattamento con ultrasuoni del pigiato (2 minuti) in confronto alla tradizionale macerazione di 10 ore su impianti di macerazione soffice. Queste esperienze di laboratorio unitamente alle prove in condizioni di cantina hanno messo in evidenza l’interessante effetto degli ultrasuoni sui precursori dei tioli delle uve; pertanto dal punto di vista tecnologico gli ultrasuoni potrebbero essere utilizzati vantaggiosamente nella gestione delle fasi di macerazione prefermentativa di varietà aromatiche contenenti precursori tiolici oppure nella produzione di succhi d’uva caratterizzati da note tropicali. I risultati di questa ricerca, unitamente ai risultati di precedenti esperienze rendono verosimile l’ipotesi di sostituzire la tradizionale macerazione delle uve bianche con un breve trattamento ad ultrasuoni del pigiato