From grape to wine: Influence of winemaking on phenolic profile and in vivo antioxidant activity

LINGUA, M.S.; FABANI M.P; WUNDERLIN, D.A.; BARONI, M.V.

Praga

Conferencia; Food Integrity Conference; 2016

Phenolic are components of wine with a great impact on its sensorial characteristics, especially colour and flavour. They have also shown beneficial effects on human health, protecting against cardiovascular and degenerative diseases. Several factors, including grape variety, grape ripeness, environmental factors and technological procedures used during winemaking, can qualitatively and quantitatively affect the phenolic composition of the grape and wine and, therefore, their nutritional and quality properties. In this sense our main goal was to assess the effects of the winemaking technology on phenolic profile of grapes and wines and the influence of these changes on the in vivo antioxidant activity (AC), considering three main varieties produced in Argentina: Merlot, Syrah and Cabernet Sauvignon. Grapes and wines samples were collected from the same vineyard in the Province of San Juan, Argentina. In vivo antioxidant activity was determined using the yeast Saccharomyces cerevisiae exposed to H2O2 as an oxidizing agent. The antioxidant activity was evaluated by measuring the survival rates of yeast and changes in antioxidant enzymes: Glutathione Reductase (GR) and Glutathione Peroxidase (GPX). Forty-five compounds, including anthocyanins, flavonols, flavanols, phenolic acids and stilbens, were identified by HPLC-PDA-ESI-MS/MS. Results show that phenolic composition and antioxidant activity vary along the winemaking process and between varieties. In vivo AC demonstrated that yeast previously incubated with grape and wine polyphenols showed enhanced resistance to H2O2. Furthermore, GR and GPx activities were positively correlated with the chemopreventive effect observed. Data obtained was analysed by multiple regression analysis (MRA) in order to evaluate the relationshi p between phenolic profile and AC of grapes and wines. Results from MRA analysis showed that Syrah had the highest AC, because of their phenolic profile characterised by the highest content in anthocyanin compounds, while the content of trans-resveratrol in Merlot grapes and wine probably contributes to its lower activity. Furthermore, changes in the phenolic profile from grape to wine, because of the winemaking process, affected the AC. In this sense, grapes were characterised by higher content of kaempferol-3-glucoside and fertaric acid that may contribute positively to its higher in vivo AC. On the other hand, ethyl gallate contributed negatively to the AC of wines. Results presented in this study underline differences in phenolic profile and in vivo antioxidant activity of products involved in the winemaking process: grape as a raw material, wine as a final product. Furthermore, our results suggest that the AC of wine depends upon the grape variety used, since it largely determines the qualitative and quantitative composition in polyphenolic compounds.