Investigation on the protective effects of the color stability of phycocyanin in vitro

Phycocyanin (PC), which is commonly extracted from marine <i>Spirulina platensis</i>, has been explored as a natural blue pigment for application in the food industry. As a pigment-protein complex, the color stability of phycocyanin could be easily affected by the variation of temperature and light intensity in environment, which limits its further utilization. Increasing the thermal- and photo-stability of phycocyanin are key challenges in its industrial production, especially in food area. In this work, the thermal- and photo-stability of phycocyanin under different pH conditions were investigated, and the underlying mechanism was studied by molecular dynamics simulation. The results showed that bingding of bovine serum albumin (2:1), sugar alcohols (10:1) and oligosaccharides (0.5:1) with phycocyanin could significantly enhance the color stability of phycocyanin under neutral, alkaline and acidic environments, respectively. The molecular dynamics simulation and molecular docking showed that sugar alcohols and oligosaccharides could establish hydrogen bonds and form an encapsulating structure with the hydrophobic regions of phycocyanin, which stabilized it in extreme environment. The current results could lay a theoretical foundation for the in-depth development and utilization of phycocyanin, and also provide guidance for the application of marine-derived natural blue pigment in the food industry.