Differentiation of Wines Treated with Wood Chips Based on Their Phenolic Content, Volatile Composition, and Sensory Parameters.

The effects of both wood chips addition and contact time on phenolic content, volatile composition, color parameters, and organoleptic character of red wine made by a native Greek variety (Agiorgitiko) were evaluated. For this purpose, chips from American, French, Slavonia oak, and Acacia were added in the wine after fermentation. A mixture consisting of 50% French and 50% Americal oak chips was also evaluated. In an attempt to categorize wine samples, various chemical parameters of wines and sensory parameters were studied after 1, 2, and 3 mo of contact time with chips. The results showed that regardless of the type of wood chips added in the wines, it was possible to differentiate the samples according to the contact time based on their phenolic composition and color parameters. In addition, wood-extracted volatile compounds seem to be the critical parameter that could separate the samples according to the wood type. The wines that were in contact with Acacia and Slavonia chips could be separated from the rest mainly due to their distinct sensory characters.

Effects of grape extracts on the in vitro activity of enzymes involved in oxidative stress regulation.

BACKGROUND/AIM: A number of in vitro and in vivo studies have investigated the potential preventive activity of grape extracts against different diseases, and have mostly focused on their antioxidant properties. The present study examined the effects of 21 extracts from stem, skin and berry from Greek grape varieties on the activity of enzymes involved in regulation of oxidative stress, namely xanthine oxidase (XO), catalase (CAT) and superoxide dismutase (SOD). MATERIALS AND METHODS: The effects of the extracts on the enzymatic activity of XO, CAT and SOD were studied spectrophotometrically. RESULTS: The tested extracts inhibited CAT and XO activity, while higher extract concentrations are required to induce SOD. However, stem and skin extracts exhibited a different inhibitory pattern against CAT and XO compared to berry extracts. The observed differences are possibly attributed to the extract polyphenolic composition. CONCLUSION: Although the induction of SOD activity suggests an antioxidant capacity, the inhibition of CAT and XO indicates a pro-oxidant action. In general, the extracts showed pro-oxidant activity, possibly dependent on both their polyphenolic composition and concentration.