Effects of metal ions, amphoteric compounds and metal chelators on the color of iron-containing and calcium-containing carminic acid solution

• 1、State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122

Abstract：The color of carminic acid is susceptible in iron-containing and calcium-containing environments, which limited its application in food. In this paper, the effects of Al3+, Zn2+, amino acids (glycine, glutamic acid), peptides (glutathione, casein phosphopeptide), whey protein isolate and ethylenediaminetetraacetic acid on the color of iron-containing and calcium-containing carminic acid solution were investigated. After adding Al3+ to pH6 and pH8 buffers, carminic acid was red, which was not affected by Fe3+ and Ca2+. The addition of Zn2+ did not improve the coloration of carminic acid in the solution containing Fe3+ and Ca2+. Glutamate, glycine, glutathione, casein phosphopeptide and whey protein isolate have no significant effect on the color of carminic acid solution containing Fe3+. The addition of glutamic acid and glutathione made carminic acid solution containing 0.1 mol/L Ca2+ appear orange and no longer produced brown floc. Glycine, casein phosphopeptide and WPI make the carminic acid solution containing Ca2+ appear gray-green. Due to the chelation of ethylenediaminetetraacetic acid, the color of carminic acid is stable. It is orange in aqueous solution and pH6 buffer and ocher-purple in pH8 buffer, and is not affected by low concentrations of Fe3+ and Ca2+. This paper provides a reference for improving the coloration of carminic acid in food system containing iron and calcium.

Keywords： food science carminic acid metal ions amphoteric compounds metal chelators color