Over-evaluation of total flavonoids in grape skin extracts containing sulphur dioxide.

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.

A traceability study on the Moscato wine chain.

To address the growing interest of consumers for information on the provenance of foodstuffs, the production chain of world renowned Moscato d'Asti white wine has been studied using the distribution of lanthanides as chemical markers. From soil to must, upon every stage of the chain, samples have been taken and analysed with ICP-MS in order to verify whether the original fingerprint of soil is maintained or not along the chain. Results of this traceability study show clearly that lanthanides fingerprint is kept unaltered in the passage soil-grapes-must, while fractionation occurs upon wine clarifying with bentonites. The second part of the work involves a study on 102 samples of Moscato d'Asti musts in order to verify how they reflect the features of the different geographical zones where they come from, and to build a basis to be able to identify possible adulterations performed by addition of foreign musts.

Influence of yeast strain on ochratoxin A content during fermentation of white and red must.

The aim of this work was to examine whether the yeast strains, responsible for alcoholic fermentation, have an influence on the concentration of ochratoxin A (OTA) in wine. Before the fermentation, OTA was added to musts up to a concentration of about 2 microg/l. OTA content was determined in white and red wines resulting from respective musts and in methanolic extract of the yeast lees (MEL). Data showed a significant reduction of OTA at the end of alcoholic fermentation. However, depending on the yeast strain involved in the fermentation, there was a difference in the content of OTA in the wines. The percentage of OTA removal during the fermentation was between 46.83% and 52.16% in white wine and between 53.21% and 70.13% in red wine. The absence of degradation products suggested an adsorption mechanism. OTA concentration in MEL resulting from red must fermentation was higher than in white. A significant amount of OTA was not recovered either from wine or from MEL.