Characterization of some Italian V. vinifera L. grape varieties on the basis of their flavonol profile

"Suspect screening metabolomics" is a mid-way approach between "targeted" and "untargeted" analysis. For this aim, a new database of putative grape and wine metabolites (GrapeMetabolomics ) was expressly constructed. Currently, this database contains around 1,100 compounds. By performing UHPLC/QTOF mass spectrometry analysis in both positive and negative ionization mode, in a grape extract averaging 320–450 putative compounds are identified. Most of these compounds are important grape metabolites, including flavonols, anthocyanins, and stilbene derivatives. In the present study, this approach was focalized on the characterization of flavonols of 18 important Italian red and white grape varieties and the method provided the identification of 15 flavonols. By performing statistical analysis (Principal Component Analysis and Cluster Analysis), the effect of the variety on the flavonol composition of the grapes was studied. Both the red and white samples fell into three different groups, respectively, on the basis of their flavonol profiles. Because the samples were cultivated in the same vineyard, their profile potentially was not affected by cultural or environmental factors. Anyway, these preliminary results will have to be confirmed by the study of grape samples collected in different years and from different vineyards

Studio dell'influenza delle differenti condizioni di stoccaggio delle vinacce sui composti aromatici varietali e di fermentazione

Grape marc is the raw material used in the production of grappa. Grape marc consists of the solid parts of the grape: skins, seeds and, sometimes, grape stalks. Quality and characteristics of the grape marc influence fundamentally the quality and characteristics of grappa. In this thesis the effects of different treatments undertaken on grapes of Prosecco and Cabernet Sauvignon before being stored and fermented, were studied. The following treatments have been investigated: acidification, refrigeration and addition of selected yeasts. Afterwards, the effects of these treatments on the chemical composition of the grape marc at storage times longer than the usual fermentation times, were studied. Finally, in order to evaluate the effect of acidification also in relation to the potential risk of biomasses of lees and grape marc, the concentration of Ochratoxin A has been investigated on the grape marc of different varieties of grapes cultivated in high risks areas.La vinaccia è la materia prima utilizzata per la produzione della grappa. E' costituita dalle parti solide dei grappoli d'uva: bucce, vinaccioli ed, eventualmente, raspi. La qualità e le caratteristiche della vinaccia determinano fondamentalmente la qualità  e le caratteristiche della grappa. In questa tesi sono stati studiati gli effetti di diversi trattamenti a cui possono essere soggette le vinacce di Prosecco e Cabernet Sauvignon prima di essere stoccate per la fermentazione, sui composti volatili e varietali della vinaccia. I trattamenti indagati sono stati: l'acidificazione, la refrigerazione e l'aggiunta di lieviti selezionati. Sono stati successivamente studiati gli effetti di tali trattamenti sulla composizione chimica quando le vinacce vengono stoccate per tempi superiori ai tempi usuali di fermentazione. Infine, al fine di valutare l'effetto dell'acidificazione anche in relazione al rischio potenziale delle biomasse di fecce e vinacce, sono stati indagati i livelli di Ocratossina A nelle vinacce di diverse varietà  d'uva coltivate in zone potenzialmente a rischio

Applications of Solid-Phase Microextraction and Gas Chromatography/Mass Spectrometry (SPME-GC/MS) in the Study of Grape and Wine Volatile Compounds

Volatile compounds are responsible for the wine “bouquet”, which is perceived by sniffing the headspace of a glass, and of the aroma component (palate-aroma) of the overall flavor, which is perceived on drinking. Grape aroma compounds are transferred to the wine and undergo minimal alteration during fermentation (e.g., monoterpenes and methoxypyrazines); others are precursors of aroma compounds which form in winemaking and during wine aging (e.g., glycosidically-bound volatile compounds and C13-norisoprenoids). Headspace solid phase microextraction (HS-SPME) is a fast and simple technique which was developed for analysis of volatile compounds. This review describes some SPME methods coupled with gas chromatography/mass spectrometry (GC/MS) used to study the grape and wine volatiles

Study of Combined Effect of Proteins and Bentonite Fining on the Wine Aroma Loss

The wine aroma loss as a consequence of treatments with bentonite is due to the occurrence of multiple interaction mechanisms. In addition to a direct effect of bentonite, the removal of aroma compounds bound to protein components adsorbed by the clay has been hypothesized, but never demonstrated. We studied the effect of bentonite addition on total wine aroma compounds (extracted from Muscat wine) in a model solution in the absence and presence of total and purified (Thaumatin-like proteins and chitinase) wine proteins . The results showed that in general bentonite alone has a low effect on the loss of terpenes, but removed ethyl esters and fatty acids. The presence of wine proteins in the solution treated with bentonite tended to increase the loss of esters with the longest carbon chains (from ethyl octanoate to ethyl decanoate), and this was significant when the purified proteins were used. The results here reported suggest that hydrophobicity can be one of the driving forces involved in the interaction of aromas with both bentonite and proteins

Characterization of Non-Anthocyanic Flavonoids in Some Hybrid Red Grape Extracts Potentially Interesting for Industrial Uses

Previous studies showed that hybrid grapes often have qualitatively and quantitatively higher polyphenolic contents than the common V. vinifera grape varieties. In general, these compounds are studied for grape chemotaxonomy and for nutraceutical purposes due to their relevant antioxidant activity. Non-anthocyanic flavonoid composition of five red hybrid grape varieties produced by crossing of V. vinifera, V. aestivalis, V. cinerea, V. berlandieri, V. labrusca, V. lincecumii, and V. rupestris were studied by liquid chromatography/high-resolution mass spectrometry. Thirty-one compounds were identified, including methylnaringenin, a tetrahydroxy-dimethoxyflavanone-hexoside, two flavonols (quercetin and a pentahydroxyflavone isomer), 20 glycoside flavonols (four quercetin, two myricetin, two kaempferol, three isorhamnetin, one laricitrin, two syringetin, one kaempferide and two dihydroflavonol derivatives; myricetin-glucoside-glucuronide; myricetin-diglucoside; syringetin-dihexoside), three flavan-3-ols (−)-epicatechin, (+)-catechin, (−)-epicatechin gallate) and four proantocyanidins (procyanidin B1, procyanidin B2, procyanidin B3 or B4/B5, procyanidin T2 or T3/T4/C1). Seibel 19881, Seyve Villard 12-347 and Seyve Villard 29-399 were particularly rich in polyphenols. These findings emphasize that these grapes are especially interesting for the production of antioxidant extracts for nutraceutical and pharmaceutical uses

Influence of Non-Saccharomyces on Wine Chemistry: A Focus on Aroma-Related Compounds

Wine fermentation processes are driven by complex microbial systems, which comprise eukaryotic and prokaryotic microorganisms that participate in several biochemical interactions with the must and wine chemicals and modulate the organoleptic properties of wine. Among these, yeasts play a fundamental role, since they carry out the alcoholic fermentation (AF), converting sugars to ethanol and CO₂ together with a wide range of volatile organic compounds. The contribution of Saccharomyces cerevisiae, the reference organism associated with AF, has been extensively studied. However, in the last decade, selected non-Saccharomyces strains received considerable commercial and oenological interest due to their specific pro-technological aptitudes and the positive influence on sensory quality. This review aims to highlight the inter-specific variability within the heterogeneous class of non-Saccharomyces in terms of synthesis and release of volatile organic compounds during controlled AF in wine. In particular, we reported findings on the presence of model non-Saccharomyces organisms, including Torulaspora delbrueckii, Hanseniaspora spp,Lachancea thermotolerans, Metschnikowia pulcherrima, Pichia spp. and Candida zemplinina, in combination with S. cerevisiae. The evidence is discussed from both basic and applicative scientific perspective. In particular, the oenological significance in different kind of wines has been underlined.Land and Food Systems, Faculty ofNon UBCReviewedFacultyResearche

Characterization of some Italian

“Suspect screening metabolomics” is a mid-way approach between “targeted” and “untargeted” analysis. For this aim, a new database of putative grape and wine metabolites (GrapeMetabolomics) was expressly constructed. Currently, this database contains around 1,100 compounds. By performing UHPLC/QTOF mass spectrometry analysis in both positive and negative ionization mode, in a grape extract averaging 320–450 putative compounds are identified. Most of these compounds are important grape metabolites, including flavonols, anthocyanins, and stilbene derivatives. In the present study, this approach was focalized on the characterization of flavonols of 18 important Italian red and white grape varieties and the method provided the identification of 15 flavonols. By performing statistical analysis (Principal Component Analysis and Cluster Analysis), the effect of the variety on the flavonol composition of the grapes was studied. Both the red and white samples fell into three different groups, respectively, on the basis of their flavonol profiles. Because the samples were cultivated in the same vineyard, their profile potentially was not affected by cultural or environmental factors. Anyway, these preliminary results will have to be confirmed by the study of grape samples collected in different years and from different vineyards