Isolation of anthocyanins by high-speed countercurrent chromatography and application of color activity concept to different red grape pomaces

Anthocyanins are natural pigments responsible for orange, pink, red, violet and blue colours in the flowers and fruits of many plants which are using as colorants in food and beverages industry. Anthocyanins (of the Greek anthos=flower and kianos=blue) are under huge investigation due to the growing interest of substitution the potential cancerogenic synthetic colors which are still using in food industry. Anthocyanins of grape pomace from three varieties “Pinot noir”, “Merlot” and “Vranec” were isolated by high -speed counter current chromatography. After purification of the fractions by means of preparative high performance liquid chromatography the structures of isolated pigments were elucidated by electrospray ionization multiple mass spectrometry (ESI- MSn) and nuclear magnetic resonance (NMR) spectroscopy. The major anthocyanin malvidin-3- glucoside and the minor pigments delphinidin-3-glucoside, cyaniding-3-glucoside, petunidin-3- glucoside, and malvidin-3-p-coumarоyl-glucoside were isolated. NMR structure elucidation confirmed the most abundant anthocyanins responsible for the color of the grape pomace. Furthermore, the color activity concept of isolated anthocyanins was performed for investigation of particular contribution of isolated pigments to the color of three different varieties of grape pomace. The “Color activity concept” was applied and visual detection thresholds of isolated anthocyanins were determined. The results of the “color activity value” of the isolated pigments and their detection thresholds were in good agreement with the color shade of the different varieties of red grape pomace.