## 2 Materials and Methods  
During our experiments, storage kinetic studies were carried out in the research laboratory and cellar of the Department of Enology of the MATE Institute of Viticulture and Enology. For fermentation, we used unsulphured 'Olaszrizing' musts from the Badacsony wine region (Hungary) in 3 different years (2017, 2018, 2019). The yeast used for the experiments was a medium sulphur dioxide-producing _Saccharomyces cerevisiae_ (SAFECENO\({}^{\text{TM}}\) VR 44 BIO). The 'Olaszrizing' musts (10-10 L) were inoculated with sulfur-producing yeast. The yeast dosage was 20 g/hl. The fermentation process was carried out at room temperature, 20 \({}^{\circ}\)C and 12 \({}^{\circ}\)C. The starter culture was prepared according to the manufacturer's recommendation. As a first step, a packet of yeast was soaked in 5 L of 30-38 \({}^{\circ}\)C dechlorinated water for 10 min and mixed to suspend the cells. The yeast suspension was then added to 20 L of unsulphurized must and allowed to stand for 20 min. The activated yeast suspension was then added to the must to be fermented and mixed thoroughly to ensure that the yeast was well suspended. The initial parameters of the musts made from the grapes used for the experiment were as seen in the following (Table 1):  
After fermentation, the wines were not sulphurized; stored in a single room at 12 \({}^{\circ}\)C cellar temperature; and measured monthly for seven months for total and free sulphur content, total polyphenol content, leucoanthocyanin and catechin, and acetaldehyde content. As a control sample, the must was not inoculated and was allowed to undergo spontaneous fermentation. In the fermented samples, the evolution of free and total sulphur dioxide and the polyphenol composition were measured for seven months. For the analytical tests, routine methods were chosen that are used in everyday laboratory practice. Statistical evaluation of the results obtained was evaluated by ANOVA one-factor analysis of variance. The results were tested at the 95% significance level (\(p=0.05\)). The measurement methods listed below were used for the studies:  
* Content of free sulphur dioxide and total sulphur dioxide [17]. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Parameter** & **2017** & **2018** & **2019** \\ \hline Titatable acidity (g/L) & 11.7 & 11.9 & 11.6 \\ pH & 3.06 & 3.12 & 3.08 \\ Content of sugar (ref\%) & 21.44 & 22.01 & 21.22 \\ Assimilable nitrogen level (mg/L) & 320 & 334 & 312 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Baseline data for the musts used for fermentation in the three vintages. Free sulfur dioxide is determined by direct titration with iodine. The combined sulfur dioxide is subsequently determined by iodometric titration after alkaline hydrolysis. When added to the free sulfur dioxide, it gives the total sulfur dioxide;
* Examination of the polyphenol composition of wines;
* Determination of total polyphenol content using the Folin-Ciocalteu reagent, calibrated for gallic acid [18]. All the phenolic compounds contained in wine are oxidized by the Folin-Ciocalteu reagent. This reagent is formed from a mixture of phosphotungstic acid, H\({}_{3}\)PW\({}_{12}\)O\({}_{40}\), and phosphomolybic acid, H\({}_{3}\)PMo\({}_{12}\)O\({}_{40}\); which, after oxidation of the phenols, is reduced to a mixture of blue oxides of tungsten, W\({}_{8}\)O\({}_{23}\), and molybdenum, MoS\({}_{0}\)O\({}_{23}\). The blue coloration produced has a maximum absorption in the region of 750 nm, and is proportional to the total quantity of phenolic compounds originally present;  
* Leucanthocyanin content was determined spectrophotometrically after heating with a 40:60 mixture of hydrochloric acid-butyl alcohol containing ferrous sulphate [19];
* For the determination of the catechol content, the wine was diluted with alcohol, reacted with sulphuric acid vanillin and measured spectrophotometrically at 500 nm [20];
* Determination of acetaldehyde was carried out by enzyme spectrophotometry (megazyme acetaldehyde assay kit from Neogene) [21].