); [EMAIL_ADDRESS] (S.C.)1 Laboratory of Food Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece; [EMAIL_ADDRESS] Laboratory of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece; [EMAIL_ADDRESS] (E.V. ); [EMAIL_ADDRESS] (S.C.)1 Laboratory of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece; [EMAIL_ADDRESS] (E.V. ); [EMAIL_ADDRESS] (E.V. ); [EMAIL_ADDRESS] (S.C.)1 Laboratory of Food Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece; irovussi@uoi.gr1 Laboratory of Food Science and Human Nutrition, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece; [EMAIL_ADDRESS] (E.V. ); [EMAIL_ADDRESS] (E.V. ); christofisteffermutation, non-enzymatic oxidation is mainly responsible for the development of the browning, which progressively dominates in white wine color [5; 6]. The most important chemical groups of polyphenols in white wines, both in terms of abundance and the capability to be involved in redox reactions, are flavanols and hydroxycinnamic acids. Oxidation of ortho-dihydroxyphenic compounds (including (+)-catechin, (-)-epicatechin, caffeic, and other hydroxycinnamates) results to the formation of ortho-quinones which take part in polymerization processes and the development of brown products [7]. Studies involving wine model solutions confirmed the formation of two types of brown compounds, xanthylium salts and ethyl-ester of xanthylium salts, both derived from oxidation and polymerization of flavanols [8]. With an absorption maximum of 440 and 460 nm, respectively, these pigments directly contribute to white wine browning during storage and ageing. These oxidation reactions lead to the formation of H\({}_{2}\)O\({}_{2}\) which, in association with ferrous ions (Fe\({}^{2+}\)), may lead to the formation of reactive oxygen species (such as hydroxyl radicals and hydroxide ions) through a reaction widely known as Fenton [9]. Hydroxyl radical is considered one of the most powerful nonselective oxidants having the ability to oxidize almost any substance in wine. The oxidation products, mainly ketones and aldehydes, are nucleophiles and are considered important compounds in color development [10]. Compounds such as sulfur dioxide, ascorbic acid, and glutathione, through their action as quinone reductants and/or scavengers, are considered important in increasing wine resistance to oxidation [11]. The browning capacity of the white wines is routinely measured by a simple test which directly measures the impact of elevated temperature on brown pigment formation. This test was initially developed by [PERSON] and [PERSON] [12] and was modified later by other researchers [13; 14] by excluding the bentonite addition step. Wine samples are subjected to heating at a constant temperature (approximately at 50 \({}^{\circ}\)C), and the browning development is followed by measuring the absorbance at 420 nm (A\({}_{420}\)) over a period of 12 days. This test permits the study of the browning development of wines within a reasonable time period, although the endpoint (where the maximum browning is attained) is chosen arbitrarily [14]. It is well-known that the kinetics of oxidation reactions are directly dependent on temperature and that the rate of browning development in white wines shows an exponential increase with temperature, having an activation energy between 66.4 and 74.6 kJ mole\({}^{-1}\)[15; 16]. Browning of white wines mainly follows zero-order kinetics [1; 14; 17]. Because browning is mainly associated with polyphenol oxidation, oxidizable substrates such as o-diphenols and hydroxycinnamic acids are implicated to a certain degree in the oxidation mechanism, and many studies have shown that the formation of quinones has a significant contribution [16]. Selenium (Se) is naturally present in wines [18] and can be found in concentrations ranging from 2 to 5 \(\mu\)g/L [19].