Effect of red wine maceration techniques on oligomeric and polymeric proanthocyanidins in wine, cv. Blaufrankisch

The influence of duration of maceration, of different maceration temperatures during the last two days of maceration, and the effect of malolactic fermentation on the content of oligomeric and polymeric proanthocyanidins in wine, cv. Blaufränkisch, were investigated using spectrophotometric methods and the NP-HPLC procedure. Results show that the duration of maceration affected the extraction from seeds more strongly, while heating of must primarily affected the extraction from skins. An increase of temperature from 25°C to 35°C during the last two days of maceration increased total anthocyanins and high molecular weight proanthocyanidins. Malolactic fermentation lowered the color of wine, the amount of total anthocyanins and total polyphenols and may reduce polymerization reactions of proanthocyanidins.

Analysis of red wine phenolics: Comparison of HPLC and spectrophotometric methods

A recently developed ion-pair normal phase HPLC method which allows a precise chromatographic evaluation of the whole class of high-molecular-mass phenolics of wine was used in order to check the performance of spectrophotometric methods. Thirty-two monovarietal red wines (vintages 1993 and 1998) were analysed for total high-molecular-mass phenolics, proanthocyanidins with 2-4 units, and proanthocyanidins formed by 5 or more units, by means of the normal phase HPLC method. In addition the following spectrophotometric assays were performed: total phenols by Folin-Ciocalteu, Bate-Smith transformation of proanthocyanidins into cyanidin and catechins and proanthocyanidins reactive to vanillin.

Effects of maceration conditions on the polyphenolic composition of red wine 'Plavac mali'

The influence of the maceration treatments on the polyphenolic composition of red wines produced from Croatian autochthonous cultivar 'Plavac mali' (Vitis vinifera L.) has been investigated. The results showed that in general different skin contact times influenced the content of anthocyanins, total phenols and vanillin index in young wines. Prolonged skin contact time significantly increased the content of low molecular weight proanthocyanidins and decreased the content of anthocyanins. Young wine produced with maceration at lower temperature demonstrated the lower content of anthocyanins and proanthocyanins. No significant differences were observed between the levels of anthocyanins, total phenols and proanthocyanidins in wines aged for 14 months. Weaker colour intensity of 14-month-aged wines was detected in the wine made with prolonged skin maceration time in which the ratio of proanthocyanidins/anthocyanidins was the highest.

Methyl salicylate glycosides in some Italian varietal wines

Glycosides are ubiquitous plant secondary metabolites consisting of a non-sugar component called an aglycone, attached to one or more sugars. One of the most interesting aglycones in grapes and wine is methyl salicylate (MeSA), an organic ester naturally produced by many plants, particularly wintergreens. To date, nine different MeSA glycosides from plants have been reported, mainly spread over the genera Gaultheria, Camellia, Polygala, Filipendula, and Passiflora. From a sensorial point of view, MeSA has a balsamic-sweet odor, known as Wintergreen. MeSA was found in Vitis riparia grapes, in Vitis vinifera sp. and in the Frontenac interspecific hybrid. We found that the MeSA glycosides content in Verdicchio wines and in some genetically related varieties (Trebbiano di Soave and Trebbiano di Lugana) was very high. In order to understand which glycosides were present in wine, the methanolic extract of Verdicchio wine was injected into a UPLC-Q-TOF-HDMS and compared to the extracts of different plants rich in such glycosides. Using pure standards, we confirmed the existence of two glycosides in wine: MeSA 2-O-β-d-glucoside and MeSA 2-O-β-d-xylopyranosyl (1-6) β-d-glucopyranoside (gaultherin). For the first time, we also tentatively identified other diglycosides in wine: MeSA 2-O-α-l-arabinopyranosyl (1-6)-β-d-glucopyranoside (violutoside) and MeSA 2-O-β-d-apiofuranosyl (1-6)-β-d-glucopyranoside (canthoside A), MeSA 2-O-β-d-glucopyranosyl (1-6)-O-β-d-glucopyranoside (gentiobioside) and MeSA 2-O-α-l-rhamnopyranosyl (1-6)-β-d-glucopyranoside (rutinoside). Some of these glycosides have been isolated from Gaultheria procumbens leaves by preparative liquid chromatography and structurally annotated by 1H- and 13C-NMR analysis. Two of the peaks isolated from Gaultheria procumbens leaves, namely MeSA sambubioside and MeSA sophoroside, were herein observed for the first time. Six MeSA glycosides were quantified in 64 Italian white wines, highlighting the peculiar content and pattern in Verdicchio wines and related cultivars. The total concentration in bound and free MeSA in Verdicchio wines varied in the range of 456–9796 μg/L and 5.5–143 μg/L, respectively, while in the other wines the bound and free MeSA was below 363 μg/L and 12 μg/L, respectively. As this compound’s olfactory threshold is between 50 and 100 μg/L, our data support the hypothesis that methyl salicylate can contribute to the balsamic scent, especially in old Verdicchio wine

On sample preparation methods for fermented beverage VOCs profiling by GCxGC-TOFMS

Introduction Aromas and tastes have crucial influences on the quality of fermented beverages. The determination of aromatic compounds requires global non-targeted profiling of the volatile organic compounds (VOCs) in the beverages. However, experimental VOC profiling result depends on the chosen VOC collection method. Objectives This study aims to observe the impact of using different sample preparation techniques [dynamic headspace (DHS), vortex-assisted liquid–liquid microextraction (VALLME), multiple stir bar sorptive extraction (mSBSE), solid phase extraction (SPE), and solid phase micro-extraction (SPME)] to figure out the most suitable sample preparation protocol for profiling the VOCs from fermented beverages. Methods Five common sample preparation methods were studied with beer, cider, red wine, and white wine samples. After the sample preparation, collected VOCs were analyzed by two-dimensional gas chromatography coupled with time of flight mass spectrometry (GCxGC-TOFMS). Results GCxGC oven parameters can be optimized with the Box–Behnken surface response model and response measure on peak dispersion. Due to the unavoidable column and detector saturation during metabolomic analysis, errors may happen during mass spectrum construction. Profiling results obtained with different sample preparation methods show considerable variance. Common findings occupy a small fraction of total annotated VOCs. For known fermentative aromas, best coverage can be reached by using SPME together with SPE for beer, and VALLME for wine and cider. Conclusions GCxGC-TOFMS is a promising tool for non-targeted profiling on VOCs from fermented beverages. However, a proper data processing protocol is lacking for metabolomic analysis. Each sample preparation method has a specific profiling spectrum on VOC profiling. The coverage of the VOC metabolome can be improved by combining complementary methods

Elicitor-induced resveratrol production in cell cultures of different grape genotypes (Vitis spp.)

Higher plants synthesize secondary metabolites in response to abiotic and biotic stress. Liquid cell culture may be a useful tool for studying phytoalexin biosynthesis during plant interaction with pathogens. Dimethyl-β-cyclodextrin (DIMEB), an oligosaccharide consisting of 2,6-methylated cyclic α(1→4)-linked glucopyranose moieties, was shown to be capable of inducing stilbene biosynthesis in liquid grape cell cultures, also in the absence of pathogenic organisms. DIMEB is capable of inducing a response in the liquid cell cultures of the Vitis vinifera cultivars Pinot Noir and Merzling and furthermore in V. amurensis and a cross between V. riparia and V. berlandieri. More detailed attention was focused on different responses in cell suspensions of Pinot Noir and the cross of V. riparia and V. berlandieri after DIMEB treatment

The occurrence of the stilbene piceatannol in grapes

Piceatannol (trans-3,3',4,5'-tetrahydroxy-stilbene) is a natural stilbene occurring in a number of plant species, and it has been shown to have beneficial effects on human health. The compound can seldom be consumed by humans, because it occurs in non-food plants, or in non-edible organs. Here we show for the first time that grapes (Vitis vinifera L. cv. Cabernet Sauvignon) have significant amounts of piceatannol (0.052 µg g-1 fresh wt). The identity of piceatannol was confirmed by HPLC and LC-MS.

Combining molecular and metabolomic analysis to evaluate transgenic Vitis vinifera plants expressing the Vitreoscilla haemoglobin (VHb)

Transgenic V. vinifera 'Brachetto' plants expressing Vitreoscilla stercoraria haemoglobin gene (vhb) were obtained by transferring the pBI-VHb construct harbouring the vhb and the nptII genes, via A. tumefaciens EAH 105. From 18 distinct transgenic plantlets, 2 lines were randomly chosen and 11 and 14 plants respectively obtained by micropropagation were acclimated for 100 days in the greenhouse, together with 10 micropropagated plants of a wild-type control line. A data-driven assessment, aimed at evaluating all measurable lowmolecular weight organic compounds in these transgenic plants was performed using UPLC-Q-TOF with an ESI interface. Comparisons between controls and transgenic lines and between the two transgenic lines detected significant differences in some metabolic patterns. For each line, a list of identified compounds was extracted from the 100 most significant biomarkers