The UV-C light enhances oxidative processes in wine. Increasing the dose of UV-C can lead to olfactoric, gustatoric and colour changes in wine. These changes are triggered by a series of photochemical reactions such as degradation of esters, the formation of odour-active substances such as 2 aminoacetophenone through the photooxidation of amino acids. Ultimately, these reactions can lead to a reduced wine quality. The presence of antioxidants like sulphur dioxide and hydrolysable tannins can stop the promoted oxidation process. The experiments were examined on four Chardonnays. Depending on the variant sulphur dioxide and hydrolysable tannins were added separately and in combination to the wine. Wines were treated with two doses of 1 kJ/L and 2 kJ/L and compared against the control wine. The results show that the simultaneous presence of both antioxidants can efficiently reduce the negative effects of UV-C treatment. With an UV-C dose of 2 kJ/L no significant changes on the basis of chemical and sensory tests were detected. Furthermore, it was found that the lower UV-C light dose promoted the formation of odour-active esters and alcohols. Additionally, the results showed that the increasing concentration of free sulphur dioxide can lead to increased formation of odour-active substance with the odour attribute burning.
Authors: Cvetkova Svetlana1 and Durner Prof. Dr. Dominik1
1Weincampus Neustadt, Institute for Viticulture and Oenology, Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz
*corresponding author: svetlana.cvetkova@dlr.rlp.de
Keywords: UV-C light, photo-oxidation, SO2, hydrolysable tannins, 2-Aminoacetophenone
