Abstract


The influence of the presence of ascorbic acid and sucrose on some food colorant degradation has been studied. For this purpose some food colorants with naphthalenic structure (Amaranth, Allura Red, Carmoisine, Ponceau 4R, Sunset Yellow and Brilliant Black BN) and some other azo dyes (Brilliant Blue FCF, Chinoline Yellow, Indigotine, Patent Blue V and Tartazine) have been investigated. Rate constant (k), time of colorant half-life (t1/2), as well as the type of the kinetic reaction have been determined. The ascorbic acid degradation in the solution with sucrose and the degradation of the investigated colorants in the solutions with a presence of ascorbic acid and sucrose under the similar circumstances have been also followed. The colorants and the ascorbic acid have been determined by high performance liquid chromatography (HPLC) with diode array detector (DAD) and UV-VIS spectrometry. It was found that sucrose stabilize the degradation of ascorbic acid which influence on the increasing of the rate constant value. The values of the rate constant are 7.70-9.70 times higher when the colorant degradation was run in the presence of 500 mg L^-1 of ascorbic acid than in the case of the presence of 100 mg L^-1 of ascorbic acid. According to the values of correlation coefficient in all the cases it happened to be first order kinetics.
It was found that the higher concentration of ascorbic acid leads to the higher rate constant and lower colorants half-life. The values of the rate constants are 2.50-4.25 times higher when the colorant degradation was run in the presence of 500 mg L^-1 of ascorbic acid than in the case of the presence of 100 mg L^-1 ascorbic acid for Brilliant Blue FCF, Chinoline Yellow, Patent Blue V and Tartazine. From the other side, the degradation of Brilliant Black BN and Indigotine is very fast with a total degradation for 6-9 days. Therefore, the rate constants for those two food colorants are much higher than for the other investigated colorants. According to the linearity of the kinetics curves (ln(c/co) v.s. time) it appeared to be first order kinetics for the interval up to 4 days.

 

 
Keywords: Food colorants, ascorbic acid, sucrose, degradation, rate constant, HPLC, UV-VIS spectrometry