Effects of high hydrostatic pressure-assisted organic acids on the copigmentation of Vitis amurensis Rupr anthocyanins

Natural anthocyanins are safer and nutritious as compared to synthetic pigments; however, their stability is poor. They can produce spontaneous copigmentation with organic acids, leading to the improvement of colour stability, albeit slowly. Box–Behnken experimental design was used to elucidate the mechanism of copigmentation between Vitis amurensis Rupr anthocyanins (0.1 mg/mL) and organic acids (0.87 mg/mL, ferulic acid: d -gluconic acid:caffeic acid:vanillic acid = 1.5:2.5:2.5:0.5, w/w/w/w) promoted by high hydrostatic pressure (HHP; 300 MPa, 2 min). The copigmentation effect and antioxidant activity of anthocyanins were also evaluated. The structure of anthocyanins was analysed using ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy, high-performance liquid chromatography, and mass spectrometry. The results of HHP copigmentation showed that the following anthocyanins were newly formed—delphinidin-3- O -catechol, petunidin-3- O -catechol, delphinidin-4-vinyl-catechol, petunidin-3- O -guaiacol, malvidin-4-vinyl-guaiacol, cyanidin-3- O -(6″- O -caffeoyl)-glucoside, peonidin-3- O -(6″- O -caffeoyl)-glucoside, delphinidin-3- O -(6″- O -caffeoyl)-glucoside, malvidin-3- O -glucoside-4-vinyl-guaiacol, and malvidin-3- O -(6″- O -feruloyl)-glucoside—owing to appropriate modifications that increased the copigmentation rate (R = 42.12%), photo-thermal stability (R > 45%), and potential antioxidant activities expressed in vivo ( p  < 0.01 vs. Model Group).