Sensory and chemical effects of postharvest grape cooling on wine quality

Abstract

Wine cellars are affected by seasonally fluctuating workloads and face challenges especially in the harvest period connected to the required timely processing of the harvested grapes. In particular, wine varieties such as Sauvignon blanc white wine and Pinot noir red wine might increase these challenges due to their elevated cultivated amounts worldwide. In addition, specific regions produce considerable amounts of autochthonous grapes, for example Gewürztraminer in South Tyrol, Italy, which during harvest creates elevated workload for the local cellars. Storing the grapes for a short period of time after harvest might decrease the need for direct processing of the grapes, flattening the workload peak. Our experiments aimed to determine the influence of grape cooling applied after harvest on the sensory and chemical aroma profile of Sauvignon blanc, Gewürztraminer and Pinot noir wines. While Pinot noir wine mainly changes its aroma profile upon storing the grapes for two days at 20 °C, Sauvignon blanc and Gewürztraminer wine aroma is also influenced when the grapes are stored at lower temperatures of between 4 and 12 °C for two or three days. An additional cold maceration step at 8 °C for 16 hours (Sauvignon blanc) or 5 to 7 days (Pinot noir) shows less influence, especially in the red wine, and might depict an alternative to the storage of the intact grapes. Our study presents a detailed investigation of changes in sensory properties and volatile organic compound concentrations in the wines upon grape cooling and/or maceration of the grapes.