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

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

Accelerated Solvent Extraction of Phenols from Lyophilised Ground Grape Skins and Seeds

The efficient extraction of phenols from grapes is an important step for their reliable quantification. The aim was to optimise the lyophilisation process and the extraction of phenols from grape skins and seeds. The phenol extraction yield from lyophilised tissues was investigated with different accelerated solvent extraction (ASE) operating conditions. Skins and seeds were separated from frozen berries and lyophilised without being ground. The weight loss during lyophilisation was followed daily. Phenols were extracted from lyophilised, cryo-ground seeds and skins with ASE at room temperature and 10.3 MPa using 80% aqueous acetone and 60% aqueous methanol. The effects of ASE operational parameters (the number of extraction cycles (ECs) and static time (ST) duration) were investigated. The yield of extracted phenols was evaluated spectrophotometrically by determining total phenolic index at 280 nm (TPI). The weight of skins and seeds significantly dropped after 24 h of lyophilisation and continued to decrease, although not significantly, up until the 9th day. The optimal lyophilisation time was estimated to be 3 days and 5 days for skins and seeds, respectively. The phenol extraction yield was significantly affected after changes of ASE conditions. Based on TPI, the optimal ASE conditions were as follows: (i) lyophilised seeds&mdash;eight ECs with 10 min ST using aqueous acetone and then four ECs with 20 min ST using aqueous methanol; (ii) lyophilised skins&mdash;eight ECs with 1 min ST using aqueous acetone and then one EC with 20 min ST using aqueous methanol