Abstract
Concentrations of caffeoyl tartaric acid (CfT), p-coumaroyl tartaric acid (CmT), caffeic acid and p-coumaric acid in 50 samples of commercial white wines were determined by high-performance liquid chromatography. The average levels of CfT, CmT, caffeic acid and p-coumaric acid were 55, 21, 2.5 and 1.7 mg/liter, respectively. Most hydroxycinnamic acids were found to be in combined form with tartaric acid in wine.
The average amounts of CfT and CmT were much higher in Koshu wines (112, 53 mg/liter) than in Sémillon (23, 5 mg/liter), Chardonnay (29, 10 mg/liter) and Riesling wines (51, 13 mg/liter). The aqueous solutions of CfT and CmT were astringent and bitter, their threshold levels were about 50 and 25 mg/liter, respectively. The oxidative browning rates of phenolic cinnamates were much lower than in d-catechin, but CfT was shown to be better substrate for enzymatic browning. Therefore, the amounts of CfT and CmT in Koshu wine were considered to influence wine quality.
