Improving the Thermal and Oxidative Stability of Food-Grade Phycocyanin from Arthrospira platensis by Addition of Saccharides and Sugar Alcohols.

The water-soluble pigment protein phycocyanin (C-PC) from cyanobacteria sp. is an excellent natural food colorant and nutritional supplement with a brilliant blue color. However, C-PC is highly unstable, especially at high temperatures and when exposed to oxidative stress. The lack of simple and economical methods for improving the stability of C-PC greatly limits the application of this functional protein in the food industry. This study investigated the effect of adding saccharides (glucose, mannose, galactose, and maltose) and sugar alcohols (mannitol and maltitol) on the stability of food-grade C-PC extracted from ; the relevant reaction kinetics were also analyzed. The results revealed that glucose, mannose, mannitol, galactose, and maltose could effectively improve the thermal stability of C-PC. This improvement was positively correlated with the concentration of the additives and decreased sharply when the temperature exceeded 60 °C. Furthermore, the results also revealed the instability of C-PC when subjected to oxidative stress and the effectiveness of glucose, mannose, mannitol, and maltose in preventing the oxidative degradation of C-PC. In general, this study demonstrates that glucose, mannose, mannitol, and maltose are promising compounds for promoting the thermal and oxidative stability of C-PC, providing an economical and effective method for C-PC preservation.