Stability of Anthocyanins from Sweet Potatoes in a Model Beverage

Model beverages containing a citrate-phosphate buffer at pH 2.8, 13% sucrose, and a colorant were stored at room temperature for 1 yr in the dark. The colorants consisted of pigment extracts from red sweet potatoes, the same extract with the acyl groups removed, cyanidin-3-glucoside from blackberries, and a commercial sample of enocyanin from grapes. The sweet potato pigments were the most stable, closely followed by those from blackberries. The deacylated samples and those containing enocyanin were much less stable, as judged by color measurements and pigment analyses.