Determination of SO2 and reducing sugars in Macedonian wines

SO2 acts as an effective antoxidant, preventing the activity of the oxidases and antimicrobial agent, showing a potential for bleaching the pigments and elimination of unpleasant odour in wines. Glucose and fructose are the main carbohydrates in grapes and wine, usually called reducing sugars. In this study, three titrimetric methods for determination of SO2 (free and total) and reducing sugars in wines were checked. The linearity, accuracy and precision of the methods were confirmed using standard solution of SO2 and reducing sugars (fructose and glucose) prepared in appropriate concentration range, as well as with low, medium and high concentrations. Additionally, the accuracy of the methods was confirmed by standard additions. Repeatability and reproducibility were confirmed with titration of real samples, analyzed with appropriate repetitions. Validated methods were applied for determination of the content of free and total SO2, as well as reducing sugars in ten Vranec wines produced with different yeasts for fermentation