## 3 Results and Discussion  
Effect of Fe (II) + H\({}_{2}\)O\({}_{2}\) on the Browning Index of Roditis-Malagouzia and Debina White Wines during Storage at 18 \({}^{\circ}\)C or 45 \({}^{\circ}\)C  
The oxidative browning of white wines was followed by measuring the absorbance at 420 nm, which is the browning index. During storage of both white wines at 18 \({}^{\circ}\)C, the browning index was increased by the time (Figure 1a,b; Tables S1 and S2). It is well known that the absorbance at 420 nm increases during wine storage [2,32]. At 18 \({}^{\circ}\)C, the addition of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture increased the browning index during storage in a dose-dependent manner (Figure 1a,b; Tables S1 and S2). These results indicate the oxidative function of the mixture Fe (II) + H\({}_{2}\)O\({}_{2}\), while the formation of hydroxyl radicals by the Fenton reaction during wine oxidation is well known [5,8,9,10,11]. Increase of the browning index by adding Fe (II) + H\({}_{2}\)O\({}_{2}\) in white wine during storage has been reported previously [32]. For the Roditis-Malagouzia wine, there was a statistically significant positive correlation between the absorbance values at 420 nm in the control samples and those to which the lower and higher concentrations of Fe (II) + H\({}_{2}\)O\({}_{2}\) were added (\(r\) = 0.959, \(p\) = 0.040, and r = 0.951, \(p\) = 0.049, respectively). Similarly, there was a statistically significant positive correlation between the absorbance values at 420 nm in the control samples of Debina wine and those to which the higher concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) was added (\(r\) = 0.967, \(p\) = 0.033). On the other hand, there was no statistically significant correlation between the absorbance values at 420 nm in the control samples of Debina wine and to those which the lower concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture was added (\(r\) = 0.894, \(p\) = 0.106). During storage of both white wines at 45 \({}^{\circ}\)C, the browning index was increased by the time (Figure 2a,b; Tables S1 and S2). It is well known that the absorbance at 420 nm increases during wine storage at higher temperatures such as 45-55 \({}^{\circ}\)C [2,33]. There was a statistically significant positive correlation between the absorbance values at 420 nm at 45 \({}^{\circ}\)C and at 18 \({}^{\circ}\)C in the control wine samples of Roditis-Malagouzia (\(r\) = 0.956, \(p\) = 0.044). Similarly, there was a statistically significant positive correlation between the absorbance values at 420 nm at 45 \({}^{\circ}\)C and at 18 \({}^{\circ}\)C in control wine samples of Debina (r = 0.972, \(p\) = 0.028). These results are in agreement with those of a previous study, in which it was reported that the only difference between the oxidative capacity of white wines stored at 20 \({}^{\circ}\)C or 55 \({}^{\circ}\)C is the time the oxidation take place [2]. At 45 \({}^{\circ}\)C, the addition of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture increased the browning index of both wines during storage in a dose-dependent manner (Figure 2a,b; Tables S1 and S2). These results indicate the cumulative oxidative result of the mixture Fe (II) + H\({}_{2}\)O\({}_{2}\) and the higher temperature of 45 \({}^{\circ}\)C. There was a statistically significant positive correlation between the absorbance values at 420 nm in the control samples of Roditis-Malagouzia wine and those to which the lower and higher concentrations of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture were added. The correlation coefficient for the first case was \(r\) = 0.950 (\(p\) = 0.05) and for the second \(r\) = 0.966 (\(p\) = 0.034). Similarly, there was a statistically significant positive correlation between the absorbance values at 420 nm in Debina wine samples and those to which the lower and higher concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture were added. The correlation coefficient for the first case was \(r\) = 0.998 (\(p\) = 0.002) and for the second \(r\) = 0.962 (\(p\) = 0.038).