The dynamic of methanol and acetaldehyde in white wines treated with sulphur dioxide and dimethyl dicarbonate

Abstract

Wine structure is very complex, consequently, the latest researches has been focused on the detailed analysis of this beverage. One of the most important compounds that can be found in wines is methanol. The toxicology of methanol and the admissible limits established by OIV, especially the effect on consumer's health, have to be considered. In this sense, the maximum permissible quantity of methanol and changes in its composition in wines must always be discussed. For this study, forty-five samples were obtained from a blend of Fetească regală and Muscat Ottonel grape varieties at the experimental wine cellar of the Oenology Laboratory of the Faculty of Horticulture from Iași. All variants were treated with 6 % SO2 solution (40, 80, 160 mg/L) and dimethyl dicarbonate liquid solution, in various ratios (0, 100, 200 μL/L). Also, in this experiment, yeasts such as Schizosaccharomyces spp. and Brettanomyces spp. were inoculated separately (S-Schizosaccharomyces pombe, B-Brettanomyces bruxellensis) and the evolution of methanol content and acetaldehyde in wines was recorded following the administration of treatments with dimethyl dicarbonate and sulphur dioxide. The main purpose of this research is to evaluate the methanol content in wine samples using a gas chromatography method and the possible transformation in wine composition (methanol concentrations) produced by DMDC. Moreover, an important compound that can be formed in wines due to SO2 presence is acetaldehyde, so, the quantity and the effect on wine composition were discussed. The results show different amounts of methanol and acetaldehyde due to the reactions of the used treatments with specific compounds of wine. The concentration of methanol and acetaldehyde in the studied wine samples are within permitted limit for white wines, 250 mg/L methanol.