## 1 Introduction  
Oxidation of white and red wines is a well-known problem in winemaking, particularly the oxidative spoilage of young wines. Oxygen ingress changes the chemical profile of wines, consequently altering their sensory attributes. Oxidation leads to a loss of the characteristic aromas of wines, the formation of new aromas characteristic of older wines or atypical aromas associated with wine spoilage, and to oxidative browning [1; 2; 3; 4]. According to recent studies, the cascade of chemical reactions constituting wine oxidation begins with the reduction of oxygen coupled to the oxidation of phenols through the redox cycling of iron between Fe (II) and Fe (III). The oxidation of wine phenolic compounds into quinones is coupled to the reduction of oxygen into hydrogen peroxide. Hydrogen peroxide in the presence of Fe II is converted to hydroxyl radicals by the so-called Fenton reaction. Hydroxyl radicals are highly unstable species that react immediately with any substances present in solution in proportion to their concentrations. Hydroxyl radicals are a very strong and non-selective oxidant and are considered to oxidize almost all wine components [5; 6; 7; 8; 9; 10]. Quinones are unstable and may undergo further reactions. These reactions may cause pigment formation, for instance, condensation reactions that form colored products with high molecular weight. As electrophiles, quinones can spontaneously react directly with nucleophilic compounds, including some phenolics, sulfhydryl compounds and amines. In the process, dimers or polymers are produced, which can form new diphenols. The regenerated o-diphenols will be oxidized renewably, ultimately accelerating the polymerization reaction of phenols [1; 5; 8; 9; 10; 11; 12]. Several antioxidants play significant roles during wine storage and oxidation. SO\({}_{2}\) protects wine from the above-mentioned cascade of oxidation reactions essentially by competing against Fe (II) for H\({}_{2}\)O\({}_{2}\). Moreover, it possibly reduces quinones back to their phenolic form [5; 10; 13; 14; 15]. Sulphur dioxide gives limited or higher protection to aroma volatiles during wine storage [16; 17]. Natural wine antioxidants, such as phenolic acids and glutathione, protect several wine aroma volatiles after bottling [18]. Thiols protect several wine aroma volatiles due to their free -SH [19]. Sulfur dioxide, phenolics and glutathione have significant effect in the browning of white wine. Sulfur dioxide levels in white wine are critical regarding browning onset [2; 20]. Among phenolic compounds, flaxan-3-ols are the compounds most directly related to the browning process in most of the white wines, while cinnates are also involved in the browning reactions, and in some wines, browning depends on the cinnates more than on the flaxan-3-ols [2; 21]. Glutathione seems to have positive effect on the browning of white wine [22]. Since oxidative browning is the most common color defect in white wines and results in serious economic losses, the determination of the susceptibility of white wines to browning is of considerable industrial interest. The accelerated methods used to determine the susceptibility of wines to browning are based on heating the wine to different temperatures, such as 55 \({}^{\circ}\)C, for different periods of time, such as 5 days, together with submitting them to aeration or to oxygenation [23; 24]. Moreover, a linear regression has been found between the browning capacity of wines oxidized at room temperature (20 \({}^{\circ}\)C) and that of wines oxidized at 55 \({}^{\circ}\)C regarding phenolic composition and other wine parameters such as sulfur dioxide, indicating that the difference between the oxidations is the amount of time in which wine browning took place [2]. Some other methodologies have also been proposed such as the use of H\({}_{2}\)O\({}_{2}\) along with heating at 60 \({}^{\circ}\)C [25; 26], and the use of electrochemical oxidation of the polyphenolic components in the wine [27].