Iron is an essential cause of fishy aftertaste formation in wine and seafood pairing.

Fishy aftertaste is sometimes perceived in wine with fish and seafood pairing. However, what component of wine clashes with seafood or what compound contributes to the unpleasant fishy aftertaste in the mouth remains an open problem. First, intensities of unpleasant fishy aftertaste of wine and dried scallop pairings were rated by sensory analysis. Second, components of the wines were analyzed. Strong positive correlations were found between the intensity of fishy aftertaste and the concentration of both total iron and ferrous ion. Moreover, the intensity of fishy aftertaste was increased by the addition of ferrous ion in model wine and suppressed by the chelation of ferrous ion in red wine. Third, potent volatile compounds of fishy aftertaste, such as hexanal, heptanal, 1-octen-3-one, (E,Z)-2,4-heptadienal, nonanal, and decanal, were determined by gas chromatography-olfactometry and gas chromatography-mass spectrometry in dried scallop soaked in red wine. The formations of these compounds depended on the dose of ferrous ion in the model wine. These results suggest that ferrous ion is a key compound of the formation of fishy aftertaste in wine and seafood pairing within the concentration range commonly found in wine.