## 3 Results and Discussion
#### 3.2.1 Total Sulphur Dioxide  
At 18 or 45 \({}^{\circ}\)C, control wine samples exhibited a sharp decrease in the content of total sulfur dioxide with respect to storage time (Tables S3 and S4). It is expected, since sulfur dioxide, the main additive antioxidant in wine, reacts at the first stage of oxidation with hydrogen peroxide and quinones [5; 10; 13; 15]. It should be noted that there was no statistically significant correlation between the content of total sulfur dioxide at 45 \({}^{\circ}\)C and the content of total sulfur dioxide at 18 \({}^{\circ}\)C in the control wine samples (\(r\) = 0.913, \(p\) = 0.087).  
At 18 \({}^{\circ}\)C, the higher the concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) added, the greater the decrease in the content of total sulfur dioxide (Tables S3 and S4). At this temperature, there was a statistically significant positive correlation between the content of total sulfur dioxide in  
Figure 2: (**a**). Effect of Fe (II) + H\({}_{2}\)O\({}_{2}\) on the levels of of absorbance at 420 nm nm of Roditis–Malagouzia wine during storage at 45 \({}^{\circ}\)C. C1: low concentration: FeCl\({}_{2}\)\(\times\) 4H\({}_{2}\)O = 0.10 mM/H\({}_{2}\)O\({}_{2}\) = 0.63 mM. C2 high concentration: FeCl\({}_{2}\)\(\times\) 4H\({}_{2}\)O = 0.25 Mm/H\({}_{2}\)O\({}_{2}\) = 1.575 mM. (**b**). Effect of Fe (II) + H\({}_{2}\)O\({}_{2}\) on the levels of absorbance at 420 nm of Debina wine during storage at 18 \({}^{\circ}\)C. C1: low concentration: FeCl\({}_{2}\)\(\times\) 4H\({}_{2}\)O = 0.10 mM/H\({}_{2}\)O\({}_{2}\) = 0.63 mM. C2 high concentration: FeCl\({}_{2}\)\(\times\) 4H\({}_{2}\)O = 0.25 Mm/H\({}_{2}\)O\({}_{2}\) = 1.575 mM.  
the control samples and those to which the low concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) was added. The correlation coefficient was \(r\) = 1.000 (\(p\)! 0.001).  
On the other hand, there was no statistically significant positive correlation between the content of total sulfur dioxide in the control samples and with those to which the high concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture was added. This can be attributed to the strong oxidative action of Fe II + H\({}_{2}\)O\({}_{2}\) mixture at both concentrations used. At 45 \({}^{\circ}\)C, the addition of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture accelerated the decrease of total sulfur dioxide content in wine samples with respect to storage time. The higher the concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture added, the greater the decrease in total sulfur dioxide content (Tables S3 and S4).  
There was a statistically significant positive correlation between the content of total sulfur dioxide in the control samples and with those to which the high concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture was added. The correlation coefficient was \(r\) = 0.963 (\(p\) = 0.037). On the other hand, there was no statistically significant correlation between the content of total sulfur dioxide in the control wine samples and those to which the low concentration of Fe (II) + H\({}_{2}\)O\({}_{2}\) mixture was added. It may be said that total sulfur dioxide is not a suitable index to follow the forced oxidative browning of white wine by adding Fe II + H\({}_{2}\)O\({}_{2}\) at 18 or 45 \({}^{\circ}\)C.  
It has been reported that total sulfur dioxide is inversely related to browning as indicated by a negative regression slope [2]. In another study, it was reported that the relative molar amounts of sulfur dioxide considered might be critical with regard to browning onset [20]. However, it has been also reported that increasing SO\({}_{2}\) concentration does not result in increased protection with regard to browning and that increased amounts of SO\({}_{2}\) might under certain circumstances be detrimental, by promoting higher browning values [20; 35].