Effects of Copigmentation on the Stability of Phycocyanin Pigments Extracted from Spirulina platensis Using Spray Dryer

Phycocyanin is a blue pigment extracted from Spirulina platensis algae as an excellent alternative for the comparison of synthetic dyes in various industries, including food industries. The aim of the present study was to assess effects of copigmentation on the stability of phycocyanin pigments using spray drying method.

An aqueous solution of phycocyanin (500 mg l-1) was prepared at three pH values of 3, 5 and 7. Then, polyphenolic compounds containing rosmarinic acid, tannic acid and digallic acid (0, 75, 150, 225 and 300 mgl-1) were separately added to the solution as copolymers. Pigment solutions were transferred into cylindrical containers with similar sizes under a light source at an intensity of 7000 l mm-2 and ambient temperature. Color changes of the solutions were assessed for 14 d. Phycocyanin pigment solution was copigmented with tannic acid (the best copolymer) and mixed with a combination of maltodextrin and Arabic gum (100:0, 75:25, 50:50, 25:75 and 0:100). Ratio of the core to the wall was 1:10. Spray dryer was used for drying and stability of the dried coated pigment powder was assessed for 14 d by investigating the absorption reduction ratio at the maximum absorption wavelength of phycocyanin (620 nm) using spectrophotometer.

Based on the results, using tannic acid (300 mgl-1) as the best copigmenting compound induced higher resistance to phycocyanin. In addition, the most stable pigment treatment was seen with maltodextrin and Arabic gum coating (ratio: 100:0). In particle size, findings showed that the powder samples containing maltodextrin were larger than the samples with Arabic gum (350.2 and 40.1 nm, respectively). Moreover, results showed that phycocyanin copigmented with tannic acid included higher resistance to environmental changes and encapsulation using spray dryer was further effective in increasing stability of phycocyanin.