Effects of Metal Ions and Food Additives on Stability of Anthocyanins from Blueberry

Anthocyanins were extracted from blueberry at 40 ℃ using ethanol acidified with citric acid at a solvent to solid ratio of 15:1 (ml:g). Effects of metal ions and food additives on the stability of the anthocyanins from blueberry were investigated. Results indicated that Ca2+, Cu2+ and Al3+ show significant color-enhancing effects while no effects on the stability of anthocyanins. Zn2+ and Mn2+ at high concentrations have color-enhancing effects and can increase the stability of blueberry anthocyanins. Fe2+, Fe3+ and Pb2+ can cause the destruction of the blueberry anthocyanins. There is clear precipitate in blueberry anthocyanins solution containing either of Fe3+ and Pb2+. However, sodium benzoate shows positive effects on the stability of blueberry anthocyanins while H2O2 and ascorbic acid can decrease the stability and result in its more rapid discoloration. Sucrose has no harmful effects to the stability of blueberry anthocyanins but presents certain color-protective effect at higher concentrations.