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Corona O.,University of Palermo | Squadrito M.,Centro per lInnovazione della Filiera Vitivinicola | Vento G.,University of Palermo | Tirelli A.,University of Milan | Di Stefano R.,University of Palermo
Food Chemistry | Year: 2014

Sulphur dioxide (SO2) proved to increase absorbance at 280 nm of grape skin and seed extracts containing it, diluted with ethanol-HCl to assess total flavonoids and anthocyanins in the same analysis. Additional absorbance at 280 nm was also observed in acetone:H2O extracts, if the acetone had not completely evaporated before the extracts were diluted with a solvent. Flavonoids were correctly quantified in the extracts when SO2 or acetone were removed by solid-phase extraction with a C18 RP as sorbent and methanol as eluting solvent. © 2014 Elsevier Ltd. All rights reserved.

Squadrito M.,Centro per lInnovazione della Filiera Vitivinicola | Corona O.,University of Palermo | Ansaldd G.,Centro per lInnovazione della Filiera Vitivinicola | Stefano R.D.I.,University of Palermo
Journal International des Sciences de la Vigne et du Vin | Year: 2010

Aims : This study aimed at acquiring knowledge of the evolution of anthocyanins from grape to wine and the possibility of deducing the varietal origin of a wine from its anthocyanin profile. Methods and results : The anthocyanin « fingerprint », or profile, of a series of autochthonous Sicilian accessions and their respective young wines was determined by HPLC-DAD in 2008. Data were evaluated by taking into account the evolution of the percentages of side-ring dioxygenated and tri-oxygenated anthocyanins, the ratio between acetylated and p-coumaroylated derivatives, and the principal component analysis (PCA) results. From grape to the end of alcoholic fermentation, the percentages of 3-glucosides of cyanidin, peonidin, delphinidin and p-coumaroylglucosides decreased, whereas those of malvidin-3-glucoside, acetylated derivatives and, in some cases, petunidin-3-glucoside increased. In many but not all wines, after malolactic fermentation, the percentages of p-coumaroylated derivatives decreased further and those of cyanidin3-glucoside and acetylated derivatives increased ; less variation was observed in malvidin-3-glucoside values. Conclusions : From grapes to young wines, the anthocyanin profiles varied mainly because of the activity of polyphenol oxidase (PPO), yeasts and lactic acid bacteria. However, they were substantially retained in wines from varieties in which tri-oxygenated side-ring anthocyanins prevailed, but were dramatically different from the respective grapes in wines from varieties rich in di-oxygenated anthocyanins, or in which the di-oxygenated forms prevailed over the tri-oxygenated ones. PCA analysis confirmed these findings. Significance and impact of the study : Only in varieties in which the anthocyanin profile of grapes is characterized by low percentages of dioxygenated side-ring forms is it possible to gain information about the varietal origin of a young wine by comparing the profiles of bom grape and wine. However, great care is required. © Vigne et Vin Publications Internationales (Bordeaux, France).

Corona O.,University of Palermo | Squadrito M.,Centro per lInnovazione della Filiera Vitivinicola | Borsa D.,Italian Agricultural Research Council | Di Stefano R.,University of Palermo
Italian Journal of Food Science | Year: 2010

This paper reports the results of a study on the ambiguous behaviour of substances with λmax at 280 nm in the determination of total flavonoids in whole grape skin extracts made from a hydroalcoholic SO 2-rich solvent, apparently not eluted with methanol after absorption on a C18 cartridge employed for sample pre-concentration and SO 2 removal. After rejecting the hypothesis that they were irreversibly absorbed on the C18 cartridge, it seemed that they reacted with other phenolics during passage through the C18 cartridge and were totally eluted with methanol in this new combined form. This new hypothesis seems very probable and is in accord with the more recent acquisition about the synthesis of anthocyanins and flavanols. © 2010.

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