Evaluation of the Effect of Different Copigmnting Compounds on the pH Stability of Phycocyanin Pigment

Phycocyanin is a pigment extracted from Spirulina platensis and can be a good alternative to synthetic dyes in various industries, including the food industry. The aim of this study was to stabilize phycocyanin and evaluate the method in pigment stability under different pH conditions. Phycocyanin (500 ppm) in solutions at three pH (3, 5, and 7) with different ratios (0, 75, 150, 225, and 300 ppm) of rosemarinic acid, tannic acid, digallic acid was mixed as a copolymer. These solutions were placed in cylindrical containers of the same size against a light source with an intensity of 7000 lux at ambient temperature. The color changes of the solutions were examined over 14 days. The structure of the microcapsules was examined using a scanning electron microscope. The average particle diameter size and zeta potential measurement of microcapsules were determined using a special particle measuring device. The results of pigment stability study showed that the use of tannic acid as a copigmenting compound has a higher resistance effect on phycocyanin and the concentration of 300 ppm has the highest resistance. The comparison of SEM showed that microcapsules containing maltodextrin were spherical with a smoother surface and had fewer wrinkles than those made with Arabic gum. The most stable pigment treatment is related to maltodextrin coating in the ratio of acid to pigment at pH=7 and the lowest pigment stability in the ratio of 0.4 times acid to pigment at pH=3. The particle size of microcapsules with different ratios in wall compositions varies between 159.2969 to 6006.637 nm. Also, the scattering index in the microcapsule varies between 0.299547 to 3.252826, which indicates the high dispersion of particles and the heterogeneity of particle size.