Kinetics of anthocyanin condensation reaction in model wine solution under pulsed light treatment

The effects of Pulsed Light (PL) technology on the anthocyanin condensation reaction in model wine solutions were investigated. Model wine solutions containing malvidin-3-O-glucoside, cyanidin-3-O-glucoside, and delphinidin-3-O-glucoside were separately prepared with the presence of (-)-epicatechin and acetaldehyde. The solutions were subjected to PL treatment with 2, 4, and 8 J/cm² energy and stored in 10 °C. The loss of anthocyanin during the treatment and the aging period fitted the first-order reaction model (R² > 98 %). Delphinidin-3-O-glucoside suffered the highest loss, only 46 % remaining after 60 s treatment; the malvidin-3-O-glucoside showed the lower loss, 72 % remaining after 60 s treatment. Furthermore, the PL treatment significantly influenced the kinetics of anthocyanin loss. The results from LC ESI TOF/Q-TOF MS/MS analysis revealed that in the PL treated samples, more peaks eluted in the chromatogram assigned to anthocyanin ethyl-linked (-)-epicatechin products, suggesting that PL treatment led to the formation of new isomers of anthocyanin ethyl-linked (-)-epicatechin. The color characteristics of the model solutions were affected by the PL treatment and the formation of ethyl-linked products. For example, the ΔE* value for samples treated with 8 J/cm² increased by 42.52, 55.73, and 45.61 % for malvidin-3-O-glucoside, cyanidin-3-O-glucoside, and delphinidin-3-O-glucoside respectively after 110 days.