UHPLC-MS/MS determination of varietal thiol precursors in Sauvignon Blanc grapes

6siVarietal thiol precursors in grapes are subject to metabolic changes during post-harvest treatments. Metabolic activity should therefore be limited after sampling to understand their biosynthesis in the berry and genetic regulation. In this study, berries were frozen in liquid nitrogen immediately after harvesting, transported in dry ice, stored briefly at -80 °C, cryo-milled and extracted without being thawed in cold methanol in a ratio of 1:4 (w/v). A UHPLC-MS/MS method for quantitative determination of the thiol precursors 3-S-glutathionylhexan-1-ol (G3MH), 3-S-cysteinylhexan-1-ol (Cys3MH), 4-S-glutathionyl-4-methylpentan-2-one (G4MMP) and 4-S-cysteinyl-4-methylpentan-2-one (Cys4MMP), glutathione, oxidized glutathione and L-methionine in grapes was developed. Reference material was provided through synthesis of precursors and their deuterium labelled analogues. The average thiol precursor content in grapes in 2013-15 was in the range 8-16 μg kg(-1) for G3MH, 1-6 μg kg(-1) for Cys3MH, 1-4 μg kg(-1) for Cys4MMP and 0.3 μg kg(-1) for G4MMP. In 2013 and 2014, the highest precursor content in mature Sauvignon Blanc grapes from vineyards located in Italy regarded G3MH, followed by Cys3MH, Cys4MMP and G4MMP. In 2015, G3MH was again the most abundant precursor, but followed by Cys4MMP, Cys3MH and G4MMP.openopenVanzo, Andreja; Janeš, Lucija; Požgan, Franc; Velikonja Bolta, Špela; Sivilotti, Paolo; Lisjak, KlemenVanzo, Andreja; Janeš, Lucija; Požgan, Franc; Velikonja Bolta, Špela; Sivilotti, Paolo; Lisjak, Kleme

Брза идентификација на пигменти во вино со примена на MALDI-TOF-MS

Во ова истражување беше проучуван профилот на антоцијани и дериватизирани пигменти во црвени вина од сортата Вранец (Vitis vinifera L.), произведени во винарската визба Тиквеш, Кавадарци. Идентификацијата на соединенијата е извршена со примена на инструменталната техника ласерска десорпција/јонизација со помош на матрица, поврзана со масен детектор со време на прелетување (MALDI-TOF-MS) [1,2], по извршена цврсто-фазна екстракција на вината, со Sep-PAK Plus C18 колони. Синапинската киселина беше користена како матрица. Идентификацијата на пикови беше извршена во позитивен мод, врз база на таргетна фрагментација на јоните од интерес (нивните М+ сигнали). Со квалитативното скенирање на антоцијаните и дериватизираните пигменти со MALDI-TOF-MS, беше потврдено присуството на глукозиди, ацетилглукозиди и p-кумароилглукозиди во анализираните вина

Best Procedures for Leaf and Stem Water Potential Measurements in Grapevine: Cultivar and Water Status Matter

: The pressure chamber is the most used tool for plant water status monitoring. However, species/cultivar and seasonal effects on protocols for reliable water potential determination have not been properly tested. In four grapevine cultivars and two times of the season (early season, Es; late season, Ls, under moderate drought), we assessed the maximum sample storage time before leaf water potential (Ψleaf) measurements and the minimum equilibration time for stem water potential (Ψstem) determination, taking 24 h leaf cover as control. In 'Pinot gris', Ψleaf already decreased after 1 h leaf storage in both campaigns, dropping by 0.4/0.5 MPa after 3 h, while in 'Refosk', it decreased by 0.1 MPa after 1 and 2 h in Es and Ls, respectively. In 'Merlot' and 'Merlot Kanthus', even 3 h storage did not affect Ψleaf. In Es, the minimum Ψstem equilibration was 1 h for 'Refošk' and 10 min for 'Pinot gris' and 'Merlot'. In Ls, 'Merlot Kanthus' required more than 2 h equilibration, while 1 h to 10 min was sufficient for the other cultivars. The observed cultivar and seasonal differences indicate that the proposed tests should be routinely performed prior to experiments to define ad hoc procedures for water status determination

Impact of Leaf Removal, Applied Before and After Flowering, on Anthocyanin, Tannin, and Methoxypyrazine Concentrations in ‘Merlot’ (Vitis viniferaL.) Grapes and Wines

7siThe development and accumulation of secondary metabolites in grapes determine wine color, taste, and aroma. This study aimed to investigate the effect of leaf removal before flowering, a practice recently introduced to reduce cluster compactness and Botrytis rot, on anthocyanin, tannin, and methoxypyrazine concentrations in Merlot' grapes and wines. Leaf removal before flowering was compared with leaf removal after flowering and an untreated control. No effects on tannin and anthocyanin concentrations in grapes were observed. Both treatments reduced levels of 3-isobutyl-2-methoxypyrazine (IBMP) in the grapes and the derived wines, although the after-flowering treatment did so to a greater degree in the fruit specifically. Leaf removal before flowering can be used to reduce cluster compactness, Botrytis rot, and grape and wine IBMP concentration and to improve wine color intensity but at the expense of cluster weight and vine yield. Leaf removal after flowering accomplishes essentially the same results without loss of yield. © 2016 American Chemical Society.reservedmixedSivilotti, Paolo; Herrera, Jose Carlos; Lisjak, Klemen; Baša Česnik, Helena; Sabbatini, Paolo; Peterlunger, Enrico; Castellarin, Simone DiegoSivilotti, Paolo; Herrera, Jose Carlos; Lisjak, Klemen; Baša Česnik, Helena; Sabbatini, Paolo; Peterlunger, Enrico; Castellarin, Simone Dieg

Optimization and Validation of a New Capillary Electrophoresis Method with Conductivity Detection for Determination of Small Anions in Red Wines

A capillary electrophoresis (CE) method has been developed and validated for determination of organic acids (oxalate, tartrate, malate, malonate, pyruvate, succinate, acetate, citrate, and lactate) and inorganic anions (sulfate and phosphate) in red wines. The separations were carried out in an automated separation system equipped with wide-bore (300 μm i.d.) fluoroplastic capillary and contact conductivity detector used for monitoring the separation and quantification of the analytes. The fast method (analysis time less than 5 min.) provided a good linearity of calibration curves (R2 > 0.9920) for the studied acids, as well as a good reproducibility of migration times (RSD < 1.5%). In total, 17 red wines were analyzed with the proposed method, including Vranec, Cabernet Sauvignon, and Merlot wines from various geographic areas (Demir Kapija, Kavadarci, Negotino, and Veles) in Macedonia. The used fully automated separation system (sample dilution not included) predetermined the developed CE method for routine analysis

Volatile phenolics in Teran PTP red wine

The volatile phenolics, 4-ethylphenol, 4-vinylphenol, 4-ethylguaiacol and 4-vinylguaiacol were quantified in Teran PTP wines that were produced in the Kras winegrowing district. The compounds were determined by using gas chromatography coupled with mass spectrometry after extraction with diethylether. Three years monitoring (2011, 2012, 2013 vintages) showed that all four undesirable compounds were identified in Teran PTP wines, however their content did not influence significantly the sensory characteristics of the wine. The average contents gained over the three-year period (2011-2013; n=82) were 153±193 µg L^-1 for 4-ethylphenol, 1265±682 µg L^-1 for 4-vinylphenol, 69±94 µg L^-1 for 4-ethylguaiacol and 128±106 µg L^-1 for 4-vinylguaiacol. 7.3 % of samples showed contents of 4-ethylphenol above the odour threshold values. For 4-vinylphenol, 4-ethylguaiacol and 4-vinylguaiacol that percentage was 98.8 %, 25.6 % and 91.5 %, respectively