"The untypical aging off-flavour" (UTA) in wine - formation and possible prevention
Hoenicke, K. | Christoph, N. | Schwab, A. | Simat, T.J. | Steinhart, H. (University of Hamburg (Germany). Inst. of Biochemistry and Food Chemistry)
2-aminoacetophenone (AAP) is known as the character impact compound being responsible for the so called "untypical aging off-flavor" (UTA) in white wines. AAP can be formed by radical oxidation of indole-3-acetic acid (IAA) triggered by sulfuration. This report presents investigations on the mechanism of AAP-formation. After synthesis of possible intermediates it could be shown that AAP is formed by indole ring cleavage via 3-(2-formylamino)-phenyl-3-oxo-propionic acid (FAPOP) and N-formylaminoacetophenone (FAP). The degradation of IAA to AAP was suppressed in the presence of radical scavengers. However, analysis of 48 grape musts and their corresponding wines revealed that the amount of IAA or the antioxidative capacity did not correlate with the UTA-intensity of the wine, whereas the nitrogen content did. Differences in the release of IAA during fermentation of musts with different nitrogen contents indicate a correlation between the nitrogen supply of the wines and the UTA-formation.
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