Storage temperature and bottling parameters are among the most important factors, which influence the development of wine after bottling. It is well studied that higher storage temperatures speed up chemical reactions and results in faster wine aging [1,2]. It is also known that higher SO2 level and lower oxygen content provide better protection and longer shelf-life for the wine. At the same time, the mechanisms of chemical transformations of wine aromas during the aging process are not fully understood. In particular, how oxidation reactions contribute to the transformations of varietal aroma compounds.In the present study , we investigated the development of Riesling wine depending on a series of bottling conditions, which differed in the free SO2 level in wine (low—13 mg/L, medium—24 mg/L, high—36 mg/L), CO2 treatment of the headspace. The wine bottles were stored in warm (~25 °C) or cool (~15 °C) conditions for 6-24 months.The main families of Riesling varietal aromas are monoterpenes and C13-norisoprenoids. The central question of this study was to investigate their transformations under different bottling conditions: reductive and oxidative. In particular, how to preserve fruity/floral monoterpenes such as linalool and to limit the formation of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).GC-MS analysis showed that the content of linalool was decreasing during the wine storage, and higher temperature induced its faster degradation and the formation of linalool oxides. Surprisingly, reductive conditions (higher free SO2 level in wine and CO2 in the headspace) had no considerable impact on the preserving of linalool and the formation of its oxides.TDN is important C13-norisoprenoid, which is formed during the aging of Riesling wine. TDN has kerosene/diesel aromas that add complexity to the wine bouquet, but become undesirable when its content becomes high. Therefore, enological and other strategies for managing TDN in wine are of interest. There are various studies, which discuss the influence of oxygen on the formation or degradation of TDN in wine [4,5]. As shown in our investigation, the TDN content is not strongly related to the oxidative or reductive conditions in wine, and was not significantly influenced by the studied bottling parameters. The main factor inducing the TDN formation was elevated storage temperature.In addition, secondary wine aromas and low molecular weight sulfur compounds were analyzed by GC. Also a sensory analysis was performed.In conclusions, the lower SO2 level in wine and higher oxygen content in the headspace had a limited impact on the varietal and secondary aromas of Riesling wine. However, the development of oxidative aromas was more intense in the wines under these “oxidative” bottling conditions. As a result, these wines were distinguished in sensory analysis as more oxidized already after 6 months of storage in warm conditions.
Authors: Tarasov Andrii1, Garzelli Frederico1, Schuessler Christoph1, Fritsch Stefanie2, Platz Claus3, Rauhut Doris2 and Jung Rainer1
1Department of Enology, Hochschule Geisenheim University
2Department of Microbiology and Biochemistry, Hochschule Geisenheim University
3Department of Beverage Research, Hochschule Geisenheim University
*corresponding author: email@example.com
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Keywords: Riesling wine, aging, TDN, oxidation, sulfur dioxide