Effect of ultrasound on the production of xanthylium cation pigments in a model wine.

As a potential novel technique in the wine-making industry, ultrasound has received considerable attention. In this paper, a model wine system was constructed to investigate the effect of ultrasonic irradiation on the formation of xanthylium cation pigment derived from the (+)-catechin and the glyoxylic acid, an oxidation product of tartaric acid, so as to explore the changing mechanism of the wine color mediated by ultrasound. The results indicate that the long-term ultrasonic treatment can enhance the formation of the xanthylium cation pigment in the model wine, which is attributed to free radicals triggered by ultrasound, meanwhile, iron ions and oxygen can influence the ultrasonic effect. All these results suggest that ultrasound is promising to be employed in regulating the formation of the yellow pigment during wine aging thus modifying the wine organoleptic characteristic.

Effect of ultrasound on the interaction between (-)-epicatechin gallate and bovine serum albumin in a model wine.

Ultrasound is considered as a potential novel technique for improving the quality of some wines. In this paper, a model wine firstly was constructed with the standards of (-)-epicatechin gallate (ECG) and bovine serum albumin (BSA) as target compounds. Then, the experiments were conducted to investigate the effect of ultrasonic irradiation on the binding properties between ECG and BSA including quenching mechanism, binding parameters, binding forces, energy transfer distance and conformational changes determined by spectral analysis. The results indicate that ultrasound definitely has some regular effects on the binding interaction of BSA and ECG, and can induced the conformation variation of BSA in the simulated wine, which may suggest that the ultrasound might be employed to modify the wine organoleptic property by regulating the interaction between phenolic compounds and proteins from the autolysis of yeasts, since they are similar to the standards of ECG and BSA, respectively.