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Item Effects of pre- and post-fermentative practices on oligomeric cyclic and non-cyclic condensed tannins in wine from Schiava grapes(Elsevier B V, Amsterdam, 2023) Darnal A; Poggesi S; Ceci AT; Mimmo T; Boselli E; Longo E; Sun QThe effects of a) pre-fermentative freezing of the grapes (- 20 °C for two weeks); b) inoculation of the grape must with Saccharomyces cerevisiae yeast, or co-inoculation with Saccharomyces cerevisiae yeast and Oenococcus oenibacteria; c) vinification with or without fermentative maceration, and d) cold stabilization with or without bentonite treatment, were studied on the profile of oligomeric condensed tannins (proanthocyanidins, PAC) with non-cyclic or macrocyclic structures in wines made from Schiava cv., a red grape variety. The samples were evaluated just before inoculation and at the bottling of the wine. Commercial Schiava wines from two different producers stored at six and eighteen months were also studied for the effect of artificially introduced dissolved oxygen, and half of these bottles were subjected to periodic mechanical stress for one year, to see the effects on the PAC profile. Freezing of the grapes increased the extraction of all non-cyclic PAC in the must, whereas tetrameric, pentameric, and hexameric cyclic procyanidins (m/z 1153, m/z 1441, m/z 1729, respectively) were not affected; only a tetrameric cyclic prodelphinidin (m/z 1169) showed a more similar trend to the non-cyclic PAC. In wines at bottling, cyclic procyanidins were higher in wines obtained by fermentative maceration (as well as most non-cyclic congeners); however, the significance of these differences depended on specific interactions between the factors. In contrast, no effect was found on the cyclic tetrameric prodelphinidin (m/z 1169). Bentonite treatment showed no significant effect on either oligomeric non-cyclic or cyclic PAC profiles. The addition of dissolved oxygen led to a significant decrease in non-cyclic trimeric and tetrameric PAC in the samples with respect to the control ones; however, the addition of dissolved oxygen did not influence the profile of the cyclic PAC. This study sheds new light on the substantial differences in the behaviour of the cyclic and non-cyclic oligomeric PAC in red wine in relation to the vinification process and in the bottle. Cyclic oligomeric PAC were more stable and less influenced by applied factors than linear PAC, again proving to be potential markers for the grape variety of wine.Item Interactive effect of pre-fermentative grape freezing and malolactic fermentation on the anthocyanins profile in red wines prone to colour instability(Springer Nature, 2023-08-01) Darnal A; Poggesi S; Ceci AT; Mimmo T; Boselli E; Longo EThe effects of pre-fermentative freezing of red grapes from Schiava variety and co-inoculation with lactic bacteria were evaluated on the profile of anthocyans of the musts and the finished wine. Peonidin-3-glucoside is the main anthocyanin in Schiava grape musts, but it was overcome by malvidin-3-glucoside at bottling. Grape freezing increased the extraction of all anthocyanins in the musts. However, the amount of all anthocyanins except peonidin-3-glucoside and malvidin-3-glucoside was lower in wines from frozen grapes than in control wines. Wines obtained with co-inoculation showed higher anthocyanin content than their respective controls. Petunidin-3-(6′′-p-coumaroyl)-glucoside, peonidin-3-(6′′-cis-p-coumaroyl)-glucoside and malvidin-3-(6′′-trans-p-coumaroyl)-glucoside were dramatically affected by the interaction of the two applied factors. Colorimetric hue (H*) was strongly correlated with peonidin-3-glucoside, and spectrophotometric tint (N) with malvidin-3-glucoside. Tint also showed a positive correlation with malolactic fermentation. Graphical abstract: [Figure not available: see fulltext.]