Fortification of White Wines with Antioxidants and Se: Impacts on Browning Development and Phenolic Content

Abstract

The present study explores the efficiency of selenomethionine (Semeth), an organic form of Se, as an antioxidant compared with commonly used antioxidants (ascorbic acid, glutathione, and potassium metabisulfite) in preventing oxidative browning in Greek white wines (Malagouzia and Retsina). The experimental procedure involved an accelerated browning test conducted over 12 days at 55 °C, measurement of antioxidant activity values (using the Folin—Ciocalteau and the free radical diphenylpicrylhydrazyl (DPPH) methods), determination of free sulfhydryl groups using the Ellman’s method, and High-Performance Liquid Chromatographic analysis of selected phenolic compounds. Semeth consistently exhibited a preserving effect on total and free SO2 content and antioxidant activity values of Malagouzia wines. Semeth also showed a protecting effect on free sulfhydryl groups (-SH), even higher than that of SO2 suggesting that its role in maintaining wine color involves more mechanisms than just the prevention of SO2 reduction. Moreover, Semeth demonstrated promising effects in preserving individual phenolic content, in particular (+)-catechin and fertaric acid, compared to the other antioxidant additions. Both browning rate constants and percentage color change values of Retsina where higher than the corresponding values of Malagouzia wines indicating greater susceptibility to browning. Browning development was dependent on the particular antioxidant added, with ascorbic acid being the least effective. The results of this study suggest that Semeth could be an important candidate for enhancing the oxidative stability of white wines, offering at the same time valuable information for optimizing antioxidant strategies in winemaking practices.