Photostability of organic red food dyes.

• Comparison of the photodegradation of three organic red dyes in solutions. • Red 40 is most stable in pure water and carminic acid in the soft drink matrix. • Both Red 40 and carminic acid showed some stabilization by anoxia. • Betanin was the most fleeting color and was not stabilized by anoxia. • Kinetics and spectral changes are used to propose degradation mechanisms. The shift from artificial to natural ingredients is a rising trend in the food industry. However, natural coloring agents tend to be less stable than their synthetic counterparts when exposed to light, air, changes in pH, and heat. This study compares the photostability of three organic red dyes, Red 40 (allura red AC), betanin and carminic acid, in aqueous and soft drink solutions. The degradation, traced through absorbance spectroscopy, is well fit to first-order kinetics. Two distinct timescales are observed in aqueous solution but only a single, faster decay in the soft drink matrix. Betanin is the least stable dye in both solvent environments and Red 40 exhibits the greatest destabilization in the soft drink solution. Anoxia has different impacts dependent upon both the dye and solvent system. The analysis provides further insight into the degradation mechanisms for these different red dyes and the role of environment on their photostability. [ABSTRACT FROM AUTHOR]