Decreasing the alcohol level and ph in wines by the “double harvest” technique

Abstract

Many vineyards along the world produce high yield and high alcohol level wines because of different factors, so bunch thinning technique has become more usual in order to balance the production. The objective of this study consists on producing low alcohol wines by using the yield obtained from the bunch thinning. Different wines of Tempranillo variety were made in the University of La Rioja during 2009-11 vintages. Every year, the harvest was performed in two different dates. The first one was developed after veraison (during the bunch thinning), and the second one was carried out as usual. The must from the first harvested was used to replace a percentage of the must from the second harvest. After that, common fermentation were developed in four liters micro-fermenters. Chemical analyses were performed on the musts obtained from the two harvests and also on the final wines. The three years results obtained by this method showed significant decreases on alcohol level, and pH and increases in total acidity, malic and tartaric acids according to the percentage of the must replacement. The analysis didn’t show significant differences on quality wine parameters such as color intensity and total phenols index, because the ratio between the berry skin content and must volume wasn’t modified during the winemaking process. The wine sensory properties weren’t modified negatively with the exception, some times, of acidity and full bodied perception. The “Double Harvest” technique allows many possibilities by combining different percentages of replaced must and obtaining several ripeness levels in both harvests. The method uses all the natural resources from the vineyard, even the unripe bunches, and the alcohol level and pH decreases are produced without any new technology or machinery which could damage the wine profile.