Optimization Of A Micro-Scale Fermentation Set-Up: Repeatability And Comparison With Larger-Scale Red Wine Fermentation

Assessing tannins in grapes remains difficult and sometimes it is insufficient to predict what will be extracted into wine. Therefore, research in viticulture tends to perform small-scale fermentations. The aim of this study was to develop and optimize a micro-scale fermentation set-up (200 g of berries) with the potential to increase the repeatability of fermentation replicates mimicking the mechanical cap management similar to standard procedures. A vineyard was established in 2003 at Hochschule Geisenheim University (Germany) with a rootstock trial (section A) using Vitis vinifera L. cv. 'Pinot Noir' grafted onto 17 rootstocks and a variability trial (section B) with 'Pinot Noir' grafted on SO4. Repeatability of the micro-scale method averaged at 12.1 % for anthocyanins, improved with increasing maturity (5.1 % to 9.1 %) a range between 4.2 % to 12.7 % was achieved for tannins, thus proving that the micro-scale winemaking method was repeatable. Though tannin concentration found in micro-scale fermentations was higher by 34 %, it was linearly correlated to the amount extracted during higher-scale fermentations (50 kg, 400 kg) (R-2 = 0.86, n = 23), argumenting for the reliability of the micro-scale method used for anthocyanins (R-2 = 0.89, n = 23). Ultimately, combined with berry analysis, this system could contribute to a better understanding of the influence of vineyard management on the extraction of phenolic compounds into wines.