Determination of Pectinesterase Activity in Grape Varieties (Vitis vinifera L.) During Vinification

Twenty red and white grape varieties (Vitis vinifera L.) were studied for pectin methyesterase activity during alcoholic fermentation of grape must. Methanol production in final wines from those grape samples was quantified. For the concentration of pectin methyl esterase activity a titrimetric method was used. Methanol concentration in final monovarietal wines quantified by Gas Chromatography Flame Ionization Detector (GC-FID). Methanol levels ranged from 30.5-121.4 mg L_1 in white wines and 61-207 mg L_1 in red wines. The highest level was found in Agiorgitiko from Nemea. Methanol content of red wines increased with fermentation time because pectinesterase activity grows with the microorganism's activity of must. All the results show that methanol levels of monovarietal red and white wines are under the maximum acceptable limits of International Office of Vine and wine (O.I. V.) and do not represent a risk to consumer health.